Feasibility Report The case for the PYREG slow pyrolysis ... I NeueAg feasibility report.pdf · The case for the PYREG slow pyrolysis process in improving the efficiency and profitability

Feasibility Report

The case for the PYREG slow pyrolysis process in improving the

efficiency and profitability of Anaerobic Digestion plants in the UK

A feasibility report from the ‘Driving Innovation in AD’ programme which looks at the case for the PYREG slow pyrolysis process in improving the efficiency and profitability of Anaerobic Digestion plants in the UK.

Project code: OIN001-408 Research date: March – June 2012 Date: June 2012

WRAP’s vision is a world without waste, where resources are used sustainably. We work with businesses, individuals and communities to help them reap the benefits of reducing waste, developing sustainable products and using resources in an efficient way. Find out more at www.wrap.org.uk This report was commissioned and financed as part of WRAP’s ‘Driving Innovation in AD’ programme. The report remains entirely the responsibility of the author and WRAP accepts no liability for the contents of the report howsoever used. Publication of the report does not imply that WRAP endorses the views, data, opinions or other content contained herein and parties should not seek to rely on it without satisfying themselves of its accuracy. Document reference: [e.g. WRAP, 2006, Report Name (WRAP Project TYR009-19. Report prepared by…..Banbury, WRAP]

Written by: Bianca Forte, Dr Mark Coleman, and Peter Metcalfe - InCrops Enterprise Hub, and Mike Weaver – Adapt Low Carbon Group.

Front cover photography: Food waste

While we have tried to make sure this report is accurate, we cannot accept responsibility or be held legally responsible for any loss or damage arising out of or in

connection with this information being inaccurate, incomplete or misleading. This material is copyrighted. You can copy it free of charge as long as the material is

accurate and not used in a misleading context. You must identify the source of the material and acknowledge our copyright. You must not use material to endorse or

suggest we have endorsed a commercial product or service. For more details please see our terms and conditions on our website at www.wrap.org.uk

http://www.wrap.org.uk/

The case for the PYREG slow pyrolysis process in improving the efficiency

and profitability of Anaerobic Digestion plants in the UK 1

Abstract

This study has demonstrated the feasibility of using the PYREG slow pyrolysis process to upgrade food waste digestate to biochar, a porous carbonaceous material that is attracting considerable interest in the horticultural sector. The use of the PYREG system to produce biochar from digestates can deliver GHG benefits by fixing the carbon in the fibrous fraction of the digestate, without having a negative effect on the energy efficiency of plants. Two main challenges around planning and permitting were identified for the production and deployment of biochar from digestates. Firstly, the use of digestate in a pyrolysis system could be subject to the Waste Incineration Directive (WID). Secondly, the biochar produced from digestate would probably be subject to Environmental Permitting Regulations (EPR). The 1,000 tpa throughput rate of the standard 500 kW PYREG units makes the technology particularly suitable for AD plants that process ≥ 30,000 tpa of food waste. Nevertheless, the capital and operational costs associated with WID and EPR compliance favour deployment of two 500 kW PYREG modules at 50,000 tpa AD plants. When considering an annual operating period of 7,500 hours, two 500kW PYREG units have the potential to deliver 660 tonnes of biochar mixed with phosphorus and potassium-rich ash. The extent to which the value for biochar can be realised will depend on the product meeting the legislative requirements. Work is under way to develop a Biochar Risk Assessment Framework (BRAF), which will work as a prelude for a PAS and/or Quality Protocol for biochar. There is a lack of studies on biochar produced from food waste digestates. Having confirmed the technical feasibility of producing biochar from food waste digestates, phase 2 of this project will demonstrate the safety and suitability of that type of biochar. There will be significant barriers to market should this information be lacking.



Executive summary

This feasibility study looked at the case for the PYREG slow pyrolysis system in improving the efficiency and profitability of food waste AD plants by upgrading the fibrous fraction of digestate to biochar, a porous carbonaceous solid material with application in horticultural products. This study was conducted by the InCrops Enterprise Hub, a UK-leading consultancy on the development, commercialisation and adoption of bio-renewables, and Mike Weaver, a Cambridgeshire-based entrepreneur who is a shareholder in PYREG GmbH, the company that manufactures the slow pyrolysis systems considered herein. The properties of biochar that support its use in horticulture include its potential in: manipulating the pH, water absorption, water holding capacity, nutrient content and nutrient retention capacity of soils; and in supporting soil biota and plant growth. These benefits vary considerably depending on the feedstocks and technologies used for biochar production. The few studies that have investigated the properties of biochars produced from digestates suggest that AD prior to pyrolysis has effects that can be advantageous in horticultural products. No studies have looked at biochar produced from food waste digestates. The commercial benefits of integrating PYREG with AD Pyrolysis uses high temperature to break down biomass or waste in an oxygen-free environment. The PYREG slow pyrolysis system employs a continuous process with temperature ranging from 450oC to 800oC and retention time of 15 to 30 minutes. The PYREG process converts one third of the energy in the feedstock to biochar. The annual throughput rate of the standard 500 kW PYREG unit would process approximately 1,000 tonnes of feedstock, producing 300 tonnes of biochar. The other two thirds of the energy available in the feedstock are converted to syngas, which is combusted in a flameless process to produce heat to perpetuate the pyrolysis process and provide spare heat, which in an AD setting can be used to dry the digestate. Two main challenges around planning and permitting were identified for the production and deployment of biochar from digestates. Firstly, the use of digestate in a pyrolysis system could be subject to the Waste Incineration Directive (WID). Secondly, the biochar produced from digestate would probably be subject to Environmental Permitting Regulations (EPR). Although the 1,000 tpa throughput rate of the standard 500 kW PYREG units makes the technology suitable for AD plants processing as little as 30,000 tpa of food waste, the capital and operational costs associated with WID and EPR compliance favour deployment of two 500 kW PYREG modules at 50,000 tpa AD plants. The total capital costs for a PYREG project of that size is just over £1M. Installation costs are approximately £100K and the annual operational costs are just under £170K. When considering an annual operating period of 7,500 hours, two 500kW PYREG units have the potential to deliver 660 tonnes of biochar mixed with phosphorus and potassium-rich ash. The extent to which the value for biochar can be realised depends on the product meeting the legislative requirements for use in horticulture. This currently means going through the EP process. Work is under way to develop a Biochar Risk Assessment Framework (BRAF) with the view to support the development of a PAS and/or Quality Protocol for biochar. The BRAF Steering Group will be devising a definition for biochar, which will possibly specify which types of feedstocks are suitable for particular applications. The assessment will be based on current and available information about biochar.



The environmental benefits of integrating PYREG with AD This study also assessed whether, from an energy and GHG emissions perspective, pyrolysing digestate from food waste is better than anaerobically digesting or pyrolysing the original feedstock (i.e. food waste) alone. The assessment comparing the three technology scenarios above was based on a range of assumptions. To provide an insight into the sensitivity of the analysis, three different sources of data on feedstock calorific content and ash content were used. The high moisture content of digestates requires energy for dewatering and drying before digestates can be pyrolysed. The modelled pyrolysis yield estimates provide surplus heat if the feedstock has a high calorific content with relatively low ash. When comparing performance on the basis of a tonne of initial feedstock, the efficiency of removal of fibre from digestate is likely to significantly affect the magnitude of impact pyrolysis provides on the GHG abatement potential. The preliminary assessment shows that, with a maximum solid fraction capture rate from digestate of source segregated food waste, AD and pyrolysis resulted in the greater energy yield and GHG abatement potential. For parameters derived from other sources for MSW and ‘food residues’ and where digestate calorific profiles were unavailable and therefore crudely estimated, AD alone was superior in energy balance and GHG abatement compared to the other technology scenarios. Conclusions Having confirmed the technical feasibility of producing biochar from post-digestion screenings using the PYREG technology, and having estimated that the integration of pyrolysis and AD can deliver GHG benefits without adversely impacting the energy efficiency of AD plants, this project now needs to demonstrate the safety and suitability of biochars from food waste digestate in horticultural products. The above will be achieved by conducting a four-month glasshouse trial with three horticultural crops, to produce data on the effects of biochar on growing media properties and on seed germination and plant growth. In order to appraise chemical hazard associated with biochar, levels of Potentially Toxic Elements (PTE) will be assessed in the biochar, the amended growing media and the foliage or edible part of plants grown. The trials will be conducted by horticultural experts from the John Innes Centre and the analysis will be carried out by a biochar expert from the University of East Anglia. Following the analysis of the results from pot trials, the biochar-enriched growing media formulations will be ranked according to their perceived utility and will be presented to industry for an assessment of potential barriers to market. This work will be conducted by the InCrops Enterprise Hub and Mike Weaver. The results from the pot trials will also inform the assessment of the potential GHG abatement benefits of incorporating biochar to growing media formulations. This work will be carried out by the InCrops Enterprise Hub. A soils expert from Rothamsted Research, who sits on the BRAF Steering Group, will be involved in the demonstration phase in an advisory capacity. This will ensure the main findings from the demonstration phase are accessible to inform the development of a regulatory approach for the production and deployment of biochar in the UK. There will be significant barriers to market should this information be lacking.



Contents

1.0 Introduction and background ....................................................................... 6 1.1 About the consortium ................................................................................. 6

1.1.1 InCrops Enterprise Hub .................................................................... 6 1.1.2 PYREG GmbH .................................................................................. 7

1.2 Objectives and methodology ....................................................................... 7 1.3 Feasibility phase ........................................................................................ 7

1.3.1 Assessment of the feasibility of producing biochar from food waste digestate ................................................................................................... 8 1.3.2 Assessment of the carbon and energy benefits of integrating pyrolysis and AD ...................................................................................................... 8 1.3.3 Assessment of the financial benefits of integrating pyrolysis and AD ..... 8

1.4 Demonstration phase ................................................................................. 8 2.0 Market potential ......................................................................................... 10

2.1 Drivers for innovation in the horticultural sector .......................................... 11 2.2 Properties of biochar ................................................................................ 12 2.3 Biochar in horticultural products ................................................................ 15 2.4 The UK industry now and into the future .................................................... 16

3.0 Technology appraisal .................................................................................. 18 3.1 Detailed description of the process ............................................................ 18 3.2 State of development of the technology ..................................................... 22 3.3 Integration of the PYREG system to an AD plant ......................................... 23

4.0 Planning and permitting aspects ................................................................ 25 4.1 Planning Permission ................................................................................. 25 4.2 Environmental Permitting Regulations ........................................................ 25 4.3 Waste Incineration Directive ..................................................................... 27 4.4 Animal By-Product Regulations .................................................................. 28 4.5 Duty of Care ............................................................................................ 28 4.6 Operator Competence .............................................................................. 28 4.7 Health and Safety .................................................................................... 29 4.8 PAS 110 and the Quality Protocol for digestates .......................................... 29

5.0 Benefits of the PYREG system in an AD setting .......................................... 32 5.1 Financial analysis ..................................................................................... 32 5.2 GHG and energy analysis .......................................................................... 37

6.0 Conclusions ................................................................................................ 41 7.0 References .................................................................................................. 43 Appendix A - Assumptions of the GHG and energy analysis ................................. 48 1.0 Reference systems ..................................................................................... 48 2.0 Exclusion of infrastructure, maintenance and capital equipment .............. 48 3.0 Feedstock parameters ................................................................................ 49 4.0 Energy substitution credits ......................................................................... 49 5.0 AD plant assumptions ................................................................................. 50 6.0 Fertiliser substitution credits ..................................................................... 51 7.0 Transport and spreading of digestate ......................................................... 51 8.0 Preparing the feedstock for pyrolysis ......................................................... 52 9.0 Pyrolysis plant assumptions ....................................................................... 53 Appendix B - Business case for the demonstration phase .................................... 55 1.0 Objectives and methodology ...................................................................... 55 2.0 Project timescale ........................................................................................ 59 3.0 Breakdown of costs .................................................................................... 60 4.0 Key personnel ............................................................................................. 61

4.1 Dr Brian Reid, University of East Anglia (UEA) ............................................ 61



4.2 Dr Ian Bedford and Barry Robertson, John Innes Centre.............................. 61 4.3 Prof Keith Goulding, Rothamsted Research ................................................. 61 4.5 Bianca Forte, Pete MetCalfe and Dr Mark Coleman, NeueAg Ltd ................... 62 4.6 Mike Weaver ............................................................................................ 62

5.0 Project Financing ........................................................................................ 63 6.0 Commercialisation of the technology post demonstration ......................... 63



1.0 Introduction and background The purpose of the WRAP programme ‘Driving Innovation in Anaerobic Digestion’ (DIAD) is to identify technologies and processes that will enable the optimisation of AD in the UK. This project looks at the case for the PYREG slow pyrolysis system in improving the efficiency and profitability of food waste AD plants by upgrading the fibrous fraction of digestate to biochar, a porous carbonaceous solid produced by thermochemical conversion of organic materials in an oxygen depleted atmosphere. The potential of biochar in sequestering carbon, improving soil structure and quality and supporting plant growth has been the focus of much research. Commercial interest in biochar is rapidly increasing in the horticultural sector, following initial success with the commercialisation of products for household applications. 1.1 About the consortium This feasibility study was conducted by NeueAg Ltd, the sister trading company of the InCrops Enterprise Hub, a UK-leading consultancy on the development, commercialisation and adoption of bio-renewables, and InCrops client Mike Weaver, a shareholder in PYREG GmbH, the company that manufactures the slow pyrolysis systems considered herein. 1.1.1 InCrops Enterprise Hub The InCrops Enterprise Hub was set up in 2008 with funding from the East of England Development Agency and the European Regional Development Fund to promote the development, commercialisation and adoption of bio-based products, processes and services. Its portfolio of services includes: market assessment, competitor analysis, technology review, funding overview and advice on low carbon strategies. Almost 300 businesses have been supported by InCrops to date, including technology suppliers, consultants, project developers and farmers involved with or interested in AD. The InCrops Enterprise Hub is supported by thirteen partners based in the East of England (Figure 1) and managed by InCrops Ltd, a spin-out company from the University of East Anglia. The combined expertise in biological and soil sciences, climate change and agricultural R&D found across the InCrops partnership is probably unrivalled in the UK. InCrops has facilitated over 40 new collaborations between industry and academia since summer 2008, including for the biochar produced by PYREG being used for research at the University of Cambridge and University of East Anglia.

http://www.incropsproject.co.uk/



Figure 1: The InCrops partnership

1.1.2 PYREG GmbH PYREG GmbH spun out from Bingen University in 2010 after six years of research on pyrolysis of sewage sludge. Bingen University has a patent on the integration of the pyro-reactor and the combustion chamber working in unison to produce the heat required to self-perpetuate the pyrolysis process. Patent protection exists in relation to most of Europe and PYREG GmbH has the exclusive licence to manufacture and market the product worldwide. PYREG GmbH employs nine staff, with expertise in business, engineering, manufacturing and electrical instrumentation, at its manufacturing plant in DÖrth, in Germany. To date, PYREG GmbH has demonstrated the suitability of the technology in processing: front-end screenings and sewage sludge at municipal wastewater treatment plants; lop greenery and screenings; miscanthus and willow; sugar beet pulp; spent grains and pomace; colza cake and grain husks; coffee pulp and powder; animal wastes such as horse manure; meat offal; sewage sludge; paper fibre; and leather sludge. Mike Weaver, a Cambridgeshire-based entrepreneur, is a shareholder in PYREG GmbH and has the exclusive license to market the system in the UK and Ireland, where he is in the early stages of introducing the technology. During the last 15 months, the University of Cambridge, University of Edinburgh and the University of East Anglia have procured research samples of biochar from PYREG. In addition, a plant propagation business based in the East of England is trialling the PYREG biochar in peat mixtures for growing brassicas ready for plug planting by automatic machines in open fields. 1.2 Objectives and methodology Phase 1 of this DIAD project on ‘The case for the PYREG slow pyrolysis system in improving the profitability of food waste AD plants in the UK’ aimed to assess the feasibility and financial and GHG and energy benefits of producing biochar from food waste digestate. Phase 2 will demonstrate the suitability, safety and GHG benefits of the biochar as a component in growing media formulations for horticultural applications. 1.3 Feasibility phase The objectives of the feasibility phase were to: investigate whether food waste digestate was a suitable feedstock for the PYREG process; and assess the financial, GHG and energy benefits of deploying the PYREG technology at UK food waste AD plants. This section



explains how the consortium set out to achieve those objectives. The results of the study are described in Chapters 2 to 6 of this report. 1.3.1 Assessment of the feasibility of producing biochar from food waste digestate A sample of post-digestion screenings produced at a food waste AD facility in the UK was pyrolysed by PYREG GmbH to assess the behaviour of the feedstock during the thermochemical process and inform to what extent the digestate would need to be dried prior to pyrolysis. A desk-based review was conducted to identify the properties of biochar that could support its use in horticultural products. A review of the legislation and policy aspects likely to affect the deployment of the PYREG technology at an AD site was carried out and the Environment Agency was approached for their views on potential planning and permitting issues around biochar production and deployment. 1.3.2 Assessment of the carbon and energy benefits of integrating pyrolysis and AD The assessment question that WRAP required was as follows: Whether, from an energy production and GHG emissions perspective, pyrolysing AD digestate is better than anaerobically digesting or pyrolysing the same feedstock alone? A comparative streamlined lifecycle assessment approach was applied to estimate the relative GHG abatement and energy use benefit of the following scenarios:

Treating digestates from anaerobic digestion of food waste in combination with a PYREG unit to produce a more recalcitrant form of carbon for sequestration.

Using the same feedstocks for anaerobic digestion only.

Using the same feedstocks with a pyrolysis unit only.

The assessment followed the principles of non-assertive comparative attributional assessment of the three scenarios above (ILCD2010). No requirement was made for a fourth reference system – the emissions and energy use that typically results from the current fate of feedstocks. The reasons why this was omitted are outlined in Appendix A. 1.3.3 Assessment of the financial benefits of integrating pyrolysis and AD A tiered approach beginning with industry experts and key players was applied to test some of the assumptions of the study. Then, a survey was conducted to investigate the extent to which digestate constituted a value or a cost to food waste AD companies. That involved different approaches: questionnaires, phone interviews and site visits. The research indicated that AD companies could also benefit from using the PYREG system as an alternative disposal route for pre-digestion screenings. This application was outside the scope of the original proposal submitted to WRAP, but the findings are briefly discussed in section Financial analysis of this report. 1.4 Demonstration phase WRAP is supporting an initiative aimed at developing a Biochar Risk Assessment Framework (BRAF) which will work as a prelude for a Quality Protocol and/or Publicly Available Specification (PAS) for biochar. Over the next two years, the BRAF Steering Group will review available data on the properties of biochars. For food waste digestates not to be overlooked as a potential feedstock for biochar, the safety and suitability of that type of biochar for horticultural applications need to be demonstrated.



That is the aim of phase 2 of this DIAD project and the key objectives of the study will be:

To demonstrate the value of biochar produced from food waste digestates in

horticultural applications.

A four-month glasshouse trial will be used to investigate the impacts of the biochar on

growing media properties (e.g. bulk density, water absorption, hydraulic conductivity,

water availability) and on plant germination and growth (three crops).

To demonstrate the safety of biochar produced from food waste digestates in

horticultural applications.

In order to appraise the chemical hazards associated with biochar, the levels of metal and

metalloid compounds and Polycyclic Aromatic Hydrocarbons will be assessed in: the

biochar from food waste digestates; the amended growing media; and in the foliage or

edible part of plants grown in the control and biochar treatments.

To assess the carbon benefits of incorporating biochar from food waste

digestates to growing media formulations.

Following the analysis of the results from the glasshouse trial, the potential GHG benefits

of incorporating biochar to growing media formulations will be assessed. A desk-based

evaluation comparing the GHG emissions associated with the production and use of

growing media using biochar amendments shall be conducted using a lifecycle approach.

This evaluation will also take into account the results obtained from experiments to

formulate growing media and resulting yields.

To model the costs at which biochar has to be supplied for growing media

applications and assess the impact of that on AD operations.

Following the analysis of the results from the glasshouse trials, the costs of biochar-

enriched growing media will be estimated and a tiered approach beginning with key

experts, and then feedstock suppliers, growing media manufacturers, professional

growers and AD operators, will be applied to consult with industry.

UK-leading scientific experts on biochar, soil sciences and plant biology have been invited to join the consortium to support phase 2 of this DIAD project. The John Innes Centre will host the glasshouse trials and together with the University of East Anglia will advise on the safety and suitability of biochar in growing media. InCrops will be the project manager and will lead on the GHG assessment and together with Mike Weaver will be responsible for the industry consultation. Rothamsted Research, who sits on the BRAF Steering Group, will join the consortium in an advisory capacity. That will ensure the main findings from the study are accessible to those involved with advising on a potential regulatory approach to manage the risks associated with the production and deployment of biochar in the UK. While potentially toxic elements are not expected to be an issue and added functionality can be expected by anaerobically digesting feedstocks prior to pyrolysis, these aspects must be addressed specifically for biochar produced from food waste digestates. There will be significant barriers to market should this information be lacking. Appendix B explains in more detail how the objectives above will be achieved.



2.0 Market potential Biochar has potential for application in a range of sectors. Its value in sequestering carbon, improving soil structure and quality and supporting plant growth has been the focus of most research to date. Worldwide some commercial activity can be observed in those areas, and biochar is finding its first routes to market as a component in growing media formulations or soil improvers. That is the focus of this study and key findings from the desk-based research on the potential for biochar in the horticultural sector are reported in this chapter.

Figure 2: Selection of biochars produced using the PYREG technology

Temperature range: 500oC to 750oC. Retention time: 15 to 20 minutes.



Applications outside the scope of this project, but which were found to be of interest to a few AD plant operators interviewed as part of this feasibility study, include the potential of biochar supplementation in increasing biogas yields. Three companies interviewed requested samples of biochar from PYREG to run lab tests in small reactors. 2.1 Drivers for innovation in the horticultural sector A total of 6.9M m3 of materials were used in horticultural products in the UK in 2009 (Defra 2010a). Growing media, which accounted for 60% of the market, are formulated from a blend of materials to provide the properties required for the multiplicity of crops produced in horticulture. Soil improvers are used to alter the structure, water-holding capacity, nutrient content and pH of soils, and are also used as surface mulches to prevent weed growth. Although horticultural products can be formulated from a range of organic feedstocks (e.g. coir, green compost and bark) and inorganic materials (e.g. vermiculite and perlite), over 2.9M m3 of peat were used in horticultural products in the UK in 2009 (Defra 2010b). About 99% of that volume was used for growing media applications. Almost half of the peat used in the UK horticultural sector is taken from lowland raised peat bogs. These are one of Europe’s rarest and most threatened habitats. In England, just 1% (around 700 hectares) of the original habitat is left. Peatlands have high environmental value: they are habitats for rare insects and plants and important bird species; they play a vital role in the water cycle and in flood management; and they store carbon as partially decomposed plants and mosses over many thousands of years. Given the importance of peatland in the UK, Defra introduced, under the Natural Environment White Paper, voluntary targets to phase out peat use in horticulture: by 2015 in the government and public sectors; by 2020 in the amateur gardeners sector; and by 2030 in the professional growers sector. Achieving these targets will require industry to deliver year-on-year reductions of around 200,000 m3 of peat, equivalent to an annual rate of reduction (in volume) of 10% (Defra 2010b). A study for Defra (2010a) looking at various scenarios for peat replacement by 2020, highlighted various challenges associated with the supply of alternative materials:

There would appear to be adequate volumes of bark to supply the percentage that this

material could contribute in low-peat or peat-free products. However, bark availability is

influenced by the economics of the timber/construction industry and there is competition

for timber by-products in the animal bedding industry.

The future availability of wood fibre is dependent on the availability of woodchips. UK

bioenergy policies (e.g. Renewable Obligation Certificates, Feed-in-Tariffs and Renewable

Heat Incentives) are expected to encourage the use of wood by-products for energy

production, increasing competition with horticultural applications.

There is a shortfall in coir supply in the UK. Most coir is produced in developing countries

where supply chains are not well established. An improvement in this area could require

investment by UK growing media companies or coir importers in production units and

infrastructure within countries such as India.

Adequate volumes of green compost could become available, but for technical reasons

this material can only be used at up to 20% in blends. The lack of availability of low

nutrient / low bulk density materials, such as the ones listed above, is a limiting factor for

increasing the use of compost in horticultural products.



The challenges above have led to a search for feedstocks not previously considered. Biochar has not been widely used by professional growers in the UK, but over the last few years has been successfully introduced into household applications. The next section of this report explains the properties of biochar that support its use in horticultural products. 2.2 Properties of biochar Biochar can be produced from a range of feedstocks, from virgin biomass wastes (e.g. from crop and timber processing) and processed biomass waste (e.g. oil cake) to livestock waste (e.g. chicken litter and cattle manure) and sewage sludge (Error! Reference source not found.). The properties of biochar that support its use in horticultural products include:

Biochar has potential to manipulate the pH of soils

Atkinson et al. (2010) report that biochars can increase electrical conductivity and cation

exchange capacity of soils and have both acidic and basic properties. Yuan et al. (2011)

showed that thermochemical processes can be used to manipulate the acidic or alkaline

nature of biochars and Mikan and Abrams (1995) report changes in soil pH of up to pH 1

unit following biochar addition.

Biochar has potential to change the water absorption and the water holding

properties of soils

Water retention in soils is closely linked to specific surface area and biochars typically

have high surface area to volume ratios (Lehman and Joseph, 2009). Liang et al. (2006)

showed that biochar inclusion in sandy soil increased specific surface area by 4.8 times

and a variety of studies have shown that biochars can increase water holding capacity.

Moisture levels in ancient, char-containing soils are higher than those in neighbouring

soils (Lehmann et al., 2003) and addition of biochar to soils increases moisture levels

(e.g. Tyron, 1948; Glaser and Amelung, 2002; Asai et al., 2009), with sandy soils

benefiting more than clay soils (Woolf, 2008).

Biochar has potential to improve soils nutrient content and retention

Biochars can contain useful levels of macro- and micro-nutrients required for plant

growth (Chan and Xu, 2009). In addition, by binding anions and cations, biochar can

enhance the availability of N and P (Liang et al., 2006; Atkinson et al., 2010) and K

(Clarholm, 1994; Mahmood et al., 2003) and increase the solubility of Ca, Mg and Mo

(Atkinson et al., 2010).

Lehmann et al. (2003) and Major et al. (2009) report that in glasshouse experiments

biochar reduced ammonium leaching by up to 60%. Steiner et al. (2008a) showed that in

Amazonian field trials biochar both reduced N leaching and increased N use efficiency.

Biochar has potential to support soil biota

Pieti inen et al. 000 and teiner et al. (2008b) show that biochar addition to soil

increases overall soil respiration and specific respiration rate (rate per microbe). Kim et

al. (2007) show that biochar supplemented soils exhibit increased bacterial biodiversity

compared to unsupplemented forest soils: 396 vs. 291 taxonomic units.

It has been suggested that biochar can increase soil nitrification (Bergland et al., 2004;

Thies and Rilling, 2009) and denitrification (Van Zweiten et al., 2009) presumably by

promoting the growth/activity of bacteria. Ishii and Kadoya (1994) and Warnock et al.



(2007) show that biochar increase plant root colonisation by arbuscular mycorrhizae,

which enhance phosphate uptake by plants.

Biochar can support plant growth

With regards to the effect of biochar on plant growth, Lehmann et al. (2003) report that

over 90% of studies on the effect of biochar on agricultural productivity show increases

in crop yield. Lehmann and Rodon (2005) report productivity increases of 20 to 220%.

The restricted nature of these studies has been noted (Blackwell et al., 2009) and further

long-term experimentation is required (Atkinson et al., 2010).

Although the findings above are very encouraging, it is noted that a variety of feedstocks and thermochemical technologies are used to produce biochar for research (Table 1), and these parameters have an important impact on biochar quality. For instance, the temperatures at which feedstocks are converted to biochar have important effects on pH, N and P levels and the formation of micropores (Chan et al. 2008 and Bagreev et al. 2001). Furthermore, biochar consists of fractions of fixed and less stable carbon. A trade-off exists between biochar yield and carbon fixation: long residence time and slow heating rate during pyrolysis tend to increase biochar yield. The addition of labile carbon to the soil may provide short-term agronomic benefit, whilst the recalcitrant carbon has been estimated to offer storage potential of 100 to 1,000 years.

Table 1: Chemical constituents of some different biochars

Biochar feedstock pH C

(g kg-

1)

N

(g kg-

1)

C/N P

(g kg-

1)

K

(g kg-

1)

Production

(oC)

Bark: Acacia mangium 7.4 398 10.4 38 260–360

Coconut shell 690 9.4 73 500

Corn residue 675 9.3 73 10.4 350

Corn residue 790 9.2 86 6.7 600

Green waste 6.2 680 1.7 400 0.2 1 450

Peanut shell 499 11 45 0.6 6.2 400

Pecan shell 7.6 834 3.4 245 700

Pecan shell 880 4.0 220 700

Poultry: litter 9.9 380 20 19 25 22 450

Poultry: Broiler litter 258 7.5 34 48 30 700

Poultry: Broiler cake 172 6.0 29 73 58 700

Rice straw 490 13.2 37 500

Sewage sludge 470 64 7 56 450

Sugarcane bagasses 710 17.7 40 500

Wood: unknown 708 10.9 65 6.8 0.9

Wood: Eucalyptus 7.0 824 5.7 144 0.6 350

Wood: Pinus ponderosa, Pseudotsuga menziesii 6.7 740 16.6 45 13.6 Wildfire

Wood: Quercus 759 1.0 759 1.1 350

Wood: Quercus 884 1.2 737 2.2 600



See Atkinson et al. (2010) for original data sources.

Unfortunately the number of studies looking at the chemical and physical properties of biochar produced from digestates is very limited (Table 2). This literature suggests that AD prior to pyrolysis has effects that can be expected to be advantageous in the use of biochar as a soil supplement. Higher surface area was observed for biochar produced from digested feedstocks, possibly as a consequence of microbes in AD digesting labile pore-filling organic matter leaving the pore-forming matrix intact. The alteration of some of the other properties (e.g. increased cation and anion ion-exchange capacities) may be a consequence of increased surface area. Nevertheless, the hypothesis that AD prior to charring has beneficial effects for use in horticultural products has not been tested directly. Also, it is noted that AD prior to pyrolysis did not have all of the same effects on the feedstocks tested and no studies were found on the properties of biochar from food waste digestates.

Table 2 - Summary of studies on the properties of biochar from digestates

Digestated sugarcane bagasse

Inyang et al. (2010) compared the physical and chemical properties of biochar prepared from digestate from anaerobically digested sugarcane bagasse with biochar prepared from bagasse

directly. The 550oC pyrolysis process produced similar levels of biochar from the two feedstocks

but the resulting biochars had very different properties. The digested bagasse biochar had: higher pH than the undigested bagasse biochar (10.9 vs 7.7); higher surface area (17.66 m2 g-1

vs 7.7 m2 g-1); higher cation (14.30 cmol kg-1 vs 4.19 cmol kg-1) and anion exchange capacity (11.19 cmol kg-1 vs 6.64 cmol kg-1, more negative surface charge (-61.7 mV vs -28.1 mV); and

altered elemental composition and altered functional groups. The higher surface area of digested bagasse biochar may be a consequence of microbes in AD digesting labile pore-filling organic

matter leaving the pre-forming matrix intact.

Digested sugar beet tailings

Yao et al. (2011) produced biochar from AD digested sugar beet tailings (DSTC) and undigested sugar beet tailings (STC). Biochar yields from pyrolysis of the two feedstocks were similar (DSTC

45.5%, STC 36.3%). The two biochars had similar pHs (DSTC 9.95 vs STC 9.45) and similar

surface functional groups, but DSTC biochar had: higher specific surface area (micropore surface area = 449 m2 g-1 vs 351 m2 g-1; mesopore surface area = 336 m2 g-1 vs 2.6 m2 g-1, reduced

negative charge -18.11 mV vs -54.23 mV) and higher phosphate binding capacity. As with biochar from bagasse digestate, electron micrographs indicate that substantial cellular structure

remains intact, although DSTC was more distinctly different from STC than the difference observed with the study above, i.e. at the microscopic level, anaerobic digestion altered sugar

beet tailings more than sugarcane bagasse.

Digested VFG-waste and humotex

Verrue (2011) produced biochar from digested VFG-waste and humotex. The feedstocks were pyrolysed at 3 different temperatures (450°C, 600°C and 700°C) and at 2 different residence

times (10 min and 30 min). After the pyrolysis process, the weight, total nitrogen, anions, BET-

surface and pore volume was measured. Higher temperatures and longer residence times resulted in a lower weight. Biochar had still 60% of the originally nitrogen and 80% of the

originally phosphorus. Longer residence times resulted in a larger BET-surface. The same was noticed for pore volume and pore size. Pyrolysis at 700°C and 30 min residence time resulted in

the biggest pore volume (0.03 cm³ g-1).

Based on the arguments above that the characteristic of feedstocks and thermochemical processes used for biochar production can have important impact on its physical and chemical properties, there is clearly a requirement for experimentation to directly test the



effects of biochar supplementation produced from food waste digestates on plant growth and crop yields. 2.3 Biochar in horticultural products Today the biggest concentration of companies involved with the commercialisation of biochar-enriched horticultural products is found in North America. Worldwide, the biochar used in horticulture is manufactured from a range of feedstocks, in their majority forestry and crop residues. In growing media applications, biochar has been mixed with other materials such as compost, microbial inoculants, chicken litter, seaweed and fertilisers. In the UK, there are two companies selling biochar products1:

Carbon Gold Ltd supplies three products targeted at home gardener applications: the GroChar® Soil Improver, pure biochar treated with microalgae, fungi and seaweed, is retailed at £2.99 for a bag of 250 g and £6.99 for a bag of 1 kg; the GroChar® Seed Compost, which contains 0.5 kg GroChar® Soil Improver in each 8 L bag, is retailed at £4.99; and GroChar® All Purpose Compost, which contains 1 kg of GroChar® Soil Improver per 20 L bag, is retailed at £8.99.

Oxford Biochar Ltd supplies two products targeted primarily for home gardener applications: a pure biochar Soil Enhancer and a Seeding Compost blend. Both are produced with biochar manufactured from agricultural wastes. A bag of 1.5 kg pure biochar Soil Enhancer for fruit and vegetables costs £6.75. The wholesale price is £2.25/kg for minimum orders of 10 kg.

Despite the good number of companies involved with the development of biochar-enriched horticultural products (worldwide), little information is publicly available on the benefits of biochar. The professional growers sector is highly specialised, as growing media formulations are used in a range of container types to produce a myriad of plants and crops. Products must favour both seedling growth and efficient nursery operations. It should be noted that some processing may be required before biochar can be used in growing media. For instance, the low bulk density and dustiness in biochar could lead to dispersion of dust during manual or mechanical handling in working environments and the fine texture of biochar could make it difficult to be incorporated in small containers. Dumrose et al. (2011) showed that pelleted biochar is easier to handle than non-pelleted biochar, and that the larger size of pellets may improve total porosity and aeration porosity in containers, important attributes for seedling growth. Another aspect to take into consideration is the cost at which biochar could be supplied for horticultural applications. When evaluating the costs of producing, transporting, storing and delivering biochar to UK fields, Sohi et al. (2010) suggest that:

The lowest price biochar would likely arise from large scale production units using non-virgin biomass wastes that already have to be managed, such as wood, green and food wastes and sewage sludge (£0-£200 per tonne). The use of such biochars in soils would most probably face greater regulatory controls though.

Biochar from virgin biomass sources could require fewer regulatory controls. These would be typically more expensive feedstocks (up to £430 per tonne), with few exceptions (e.g. arboriculture arisings). If a low cost (from £10-£20 per tonne) straw feedstock were secured, biochar could be produced from £11-£200 per tonne.

1 Charcoal, on the other hand, is already an element of growing media produced and sold in the horticultural sector in the UK,

where practitioners contend that it improves root health and water supply.

http://www.carbongold.com/

http://www.oxfordbiochar.com/



The market research conducted as part of this feasibility study indicates that in the UK biochar produced from high-quality feedstocks is being supplied at £600 / tonne for R&D. The retail prices for Carbon Gold and Oxford Biochar products suggest that the (wholesale) value at which biochar is supplied to growing media manufacturers is much lower. In Switzerland and Austria, high-quality biochar for application in R&D is attracting a value of €685 per tonne, whilst biochar supplied to farmers, who mix it with animal manure prior to spreading on land, is attracting a value of €390 per tonne. In addition to delivering the performance expected by end-users, and being available at competitive costs, materials for peat replacement must be available in the volumes required to justify investments in new product development. This means that by-products of other industries should only be used for biochar production if they are available in large volumes. The next section discusses the projected growth for the AD industry in the UK and how much biochar could be produced from food waste digestate. 2.4 The UK industry now and into the future There are 214 AD facilities in the UK today with combined capacity to treat over 5M tpa of food waste, agricultural residues and sewage sludge (WRAP, 2012). Of those, 44 plants treat about 3.7M tpa of source-segregated Municipal Solid Waste (MSW) and commercial and industrial wastes. Some further 78 waste-fed plants have received planning consent and are at various stages of commissioning. Digestate produced from source-segregated MSW and food waste from commercial and industrial sources generally leaves the digester as a liquid slurry of 3-7% Dry Solids (DS). As examples, a typical 30,000 tpa AD plant produces approximately 82 m3 of digestate at 3% DS per day, whilst a 50,000 tpa plant produces around 137 m3 (Table 3). Our consultation with industry experts indicates that the typical energy content of food waste digestate is in the range of 12-18 MJ/kg DS. A sample of post-digestion screenings containing starch bags, analysed by a certified laboratory as part of this feasibility study, indicates a Gross CV value of 22.4 MJ/kg DS. The typical energy content requirement for feedstocks for the PYREG process is 10 MJ/kg DS. Based on the range for energy content above, PYREG advised that the DS content of digestates suitable for the pyrolysis process would be in the range of 60-70%. Based on the figures provided by suppliers of drying equipment (Table 3), it was calculated that 3.6 m3 and 5.9 m3 of dry digestate at 60% DS could be produced per day at 30,000 tpa and 50,000 tpa AD plants (respectively).

Table 3: Volumes of digestate, cake and dried cake produced at two sizes of AD plants

DIGESTATE CAKE DRIED CAKE

30,000 tpa AD plant

Volume (m3/day) 82.19 8.99 3.6

Thickness (% DS) 3 26 65

Mass (kg DS / day) 2,465 2,314 2,340

50,000 tpa AD plant

Volume (m3/day) 136.98 14.99 5.99



Thickness (% DS) 3 26 65

Mass (kg DS /day) 4,109 3,899 3,897

If operated 24 hours per day, with a 120-180 kg/hr throughput range, the standard 500 kW PYREG unit would require between 2.9-4.3 tonnes of feedstock per day. Therefore, the volumes of dry digestate produced at a 30,000 tpa AD plant (3.6 m3) should be sufficient to run the PYREG unit on its lower capacity. A 50,000 tpa plant would produce enough dry digestate (5.99 m3) to run two PYREG units. From the current installed capacity of 3.7M tpa in the food waste AD sector, 162,000 m3 of dry digestate (if upgraded from 3% DS to 60% DS) could be produced. A third of the feedstock could be converted to biochar using the PYREG system. Therefore the quantity of biochar that could be supplied by the food waste AD industry is approximately 54,000 tpa. Although the figure above seems small compared to the volumes of peat used in horticultural products today (3M m3), it is not expected for biochar to be a direct substitute for peat in growing media. Instead, it is expected that biochar will provide an opportunity to address some challenges around the use of other peat alternatives, which could be available in the volumes required to displace peat, but that due to technical reasons are limited in the extent to which they can be incorporated into growing media formulations (see section Drivers for innovation in the horticultural sector). About 7M tonnes of food waste are sent to landfill per year (WRAP, 2009). With the revenue-based renewable energy incentives available for AD and targets for landfill diversion the sector is set to grow considerably2. Defra (2010c) suggests that by 2020 there could be 5M tpa of food waste available for AD. Looking at the potential for biochar production from an installed capacity of 5M tonnes, a total of 600 m3 of dry digestate could be produced (60% DS), from which 200 tpa of biochar could be produced.

2 Firm projections for growth are difficult to obtain due to complex aspects, such as investors’ confidence on the long-term

revenue-based government support for renewable energy.



3.0 Technology appraisal Pyrolysis uses high temperature to break down biomass or waste in an oxygen-free environment. Depending on the technology of choice, feedstocks submitted to the process are converted into syngas, which can be combusted in a secondary process to generate heat, pyrolysis oil, which has potential as feedstock for liquid biofuels; and biochar. Heating rate, peak temperature and residence time at peak temperature have important impact on the volume and quality of outputs (Table 4). A range of systems can be used for biochar production, from relatively simple approaches (e.g. covered pit, covered mounds, burn barrels, kilns and drum retorts), to manufactured systems that are said to provide the process control required to engineer biochar for specific applications. Up to 12 biochar pyrolysis technologies, at a development stage similar to the progress PYREG has reached, are available globally. This chapter does not review other technologies, but highlights some aspects of PYREG that make it particularly suitable for integration with AD.3

Table 4: Scope of pyrolysis output and yield ranges

SLOW INTERMEDIARY FAST

PROCESS

Temperature (oC)

Range 250 - 750 320 - 500 400 - 750

Typical 350 - 400 350 - 450 450 - 550

Retention time

Range Min - days 1 - 15 min ms - s

Typical 2 - 30 min 4 min 1 - 5 s

YIELDS (% of o.d. feedstock)

Biochar

Range 2 - 60 19 – 73 0 - 50

Typical 25 - 35 30 – 40 10 - 25

Liquid

Range 0 - 60 18 – 60 10 - 80

Typical 20 - 50 35 – 45 50 - 70

Gas

Range 0 - 60 9 – 32 5 - 60

Typical 20 - 50 20 – 30 10 - 30

Adapted from: Sohi et al. (2010)

3.1 Detailed description of the process The main PYREG process equipment comprises of 2 pyro-reactors, 1 combustion chamber, 2 screw conveyers, 1 control panel and 1 feed hopper. Most of the equipment is mounted inside a shipping container with open sides (dimensions L 8.2 m x W 3.5 m x H 2.7 m), apart from the feed hopper, control panel and product discharge chute which are mounted externally (Figure 3). The PYREG technology weighs approximately 10 tonnes.

3 For a review of technologies see Collison et al. (2009), Lehmann and Joseph (2009) or Sohi et al. (2009).

http://www.fao.org/docrep/x5328e/x5328e06.htm

http://www.fao.org/docrep/x5328e/x5328e07.htm

http://www.anvilfire.com/FAQs/OErjan_charcoal.htm

http://www.stewardwood.org/resources/DIYcharcoal.htm

http://greenyourhead.typepad.com/files/backyard_biochar_kiln_instructions.pdf



Figure 3: Cut away drawing of the 500kW PYREG unit in standard shipping container

The PYREG system uses two pyro-reactors for heating and carbonising of the feedstock. The feedstock, loaded into a truncated shaped hopper bin external to the shipping container, is transferred from the feeder bin, which has a level control monitor, via a horizontal, torque controlled screw conveyor and metering device, to the pyro-reactors. Two motor-driven rotary valves ensure anaerobic supply of fuel, providing fire back protection. The rate of distribution is from 120 kg/hr to 240 kg/hr, or up to 1,800 tonnes of feedstock per year, depending on the type of material being used. During the conveying process through the pyro-reactor, the feedstock is subjected to thermal degradation between 450oC to 800oC for 15 to 30 minutes. Inside the central column of the pyro-reactor there are two contra-rotating, interlocked, helical screws driven by a geared motor unit (Figure 3 and Figure 4). The risk of flammable gases escaping from the plant is avoided because the continuous process conditions are maintained at a small negative pressure (differential pressure to atmosphere 0.5-1.5 mbar) by induced draft fans that operate on a duty-standby basis together with a battery back-up system to automatically shut down the process in case of mains electrical failure.

Combustion chamber

Pyrolysing reactor Feed hopper

Exhaust system with optional heat recovery

Biochar discharger conveyer

LPG storage for start up



Figure 4: Process flow diagram of the PYREG slow-pyrolysis technology

To prepare the process to become self-perpetuating, the combustion chamber needs to be fired, initially, by a supply of gas from an LPG tank or natural gas mains. Normally this start-up period takes approximately 45 minutes. Syngas and volatile components are produced while the feedstock travels through the pyro-reactors. These products are transferred, through pipes, to the adjacent combustion chamber where they are mixed with air and burnt at about 1,250oC (Figure 5). The exhaust gases from the combustion chamber are then passed through the annular space formed between the central tube and the outer casing of the pyro-reactor, ensuring the temperatures required to perpetuate the pyrolysis process. Each pyro-reactor is inclined at about 25 degrees to the horizontal with the heated emissions flowing top downwards. The exhaust gases from the pyro-reactor pass through a heat exchange system, via a cyclone (to remove dust particles) and exit the process through a chimney stack.



Figure 5: Combustion diagram showing the PYREG operating temperature range

- 500oC to 900oC - which results in very low NOx emissions

To harness the useful downstream exhaust gas a heat exchanger is coupled to the exit flue pipe wor . everal development ‘add on’ options are available to harness the spare heat to aid upstream processes. There is a development in train to add a hot air turbine or a Rankine engine to the module to generate between 9 kW and 19 kW of electricity as well as heat for drying the feedstocks to a DS level suitable for pyrolysis. The solid component, biochar and ash, is removed from the pyro-reactors via a screw conveyor controlled by a rotary sluice valve. A screw conveyor to the rotary valve and one rotary valve ensure air-tight discharge and backfire protection. The biochar and ash are recovered after passing through a secondary rotary valve, via a screw conveyor, into a settling bin or shelter, where they can be stored. The biochar receives a fine water spray to prevent self-ignition. Storage is recommended to take place in a bay or bays of a covered industrial building or barn. A control panel situated outside the shipping container offers a multifunctional touch screen section to enable the seven motor drives serving the material handling to be programmed and to enable temperature settings and air control to be managed. This enables process optimisation, particularly with respect to the λ lambda air O2)/fuel ratio of the process. In the case of a fault occurring in the production process the safety monitoring system automatically triggers a controlled plant shutdown together with diagnostic reporting through the SCADA equipment. The PYREG process has been designed to cope with a range of moisture content in feedstocks but general minimum requirements are calorific value of 10 MJ/kg and Dry Solids (DS) in the order of 55%. Particles should be smaller than 30 mm long, 20 mm wide and 15 mm thick. The feedstock must be free from contaminates such as pieces of metal, stones and ceramics that could cause jamming or damaging the flights and moving parts of the



conveying equipment. Small amounts of fines such as sand/grit aggregates of up to 5 mm in diameter can be tolerated provided attention is paid to removing any build up of these kinds of materials at possible collection points along the conveying pathway of the process. Table 4 lists the key components of the PYREG system and their technical specification. The total power demand of the 500 kW PYREG unit is approximately 6 kW. The equipment requires a 400 volt AC 50 Hz 3-phase supply. There is a standard external 32A DIN male socket mounted in the wall of the control panel situated outside the shipping container, to facilitate connecting a power supply. The design life, assuming a recommended maintenance and part replacement schedule is adhered to, is 15 years for mechanical equipment and 10 years for electrical and electronic equipment.

Table 5: Components of the PYREG system and their technical specifications

Component Specification

Fuel feeder hopper / distributor Size: ca. 2,400 x 1,600 x 1,500 mm

Volume: ca. 5.5 m3

Pyro-reactor Size: ca. 3,500 x 750 x 610 mm

Combustion chamber Size: ca. 2,000 x 2,400 x 2,000 mm (with stand)

Weight: ca. 4,000 kg

Biochar discharge conveyer Size: ca. 3,000 x 350 mm

Electrical control cabinet Size: ca. 2,200 x 1,200 x 550 mm

Control: Siemens SPS7-300

3.2 State of development of the technology Since 2008 there have been a series of PYREG demonstration exercises. The first ones, based at a municipal wastewater treatment plant in Germany, involved the pyrolysis of dewatered and dried digestates coming from primary and secondary sludges and front-end screenings from the treatment works. Production of PYREG systems started in July 2010, with the establishment of a manufacturing plant in DÖrth. Production capacity is expected to increase from ten 500kW modules in 2012 to seventy-two modules per year by 2015. Three commercial 500kW PYREG modules have been delivered to date:

The first plant, commissioned in June 2010 in Switzerland for the Delinat Institute, processes a range of biomass, from woodchips, pruning of vines to pomace from the crushing of grapes. A range of biochar-enriched composts are marketed for selected horticultural use and biochar is supplied wholesale to research institutes in Europe.

The second plant, supplied to a farming cooperative in Switzerland in December 2011, processes crop residues, wood cuttings and animal bedding, amongst other feedstocks classed as farm waste. The biochar products are currently shared out amongst the members of the cooperative for soil improvement use on their land.

A third commercial plant, commissioned at a composting plant in Austria in December 2011 (Figure 6), processes paper pulp sludge mixed with husks from crops such as corn and wheat. The biochar is supplied in a bulk wholesale trade to local farmers who mix it with farm manures before applying it to land.



Figure 6: The 500 kW PYREG unit installed at an Austrian composting company

PYREG have, on permanent loan, one pilot plant operating in Germany, as a forerunner to a four module unit, with each module rated at 500 kW. Although the PYREG technology is not currently used to treat digestates from food waste, the experience the company has gained with paper pulp sludge and sludges from the wastewater industry should be invaluable in developing solutions for the AD sector. 3.3 Integration of the PYREG system to an AD plant This section explains how the PYREG system could be retrofitted to existing AD facilities or integrated to new projects at the design stage. Figure 7 illustrates how the unit could be integrated to an AD site and shows the ancillary equipment required to enable the utilisation of digestate as feedstock for the process. The planning and permitting implications of integrating pyrolysis and AD are addressed in the next chapter.



Figure 7: Schematic diagram showing the integration of PYREG to an AD site

The typical energy content requirement for feedstocks for the PYREG process is 10 MJ/kg DS. Digestate produced from food waste generally leaves the digester as a liquid slurry of 3-7% DS and its typical energy content is in the range of 12-18 MJ/kg DS or up to 22.4 MJ/kg DS containing starch bags. Based on the calorific values above, PYREG has advised that the DS content of food waste digestates for the pyrolysis process should be in the range of 60-70%. Therefore, a screw-press, centrifuge, belt press or filter press is required to upgrade the DS content of the digestate from 3-7% to 25-45%. Potential suppliers include FAN, Bauer, Huber, Alfa Laval, Westfailia and Hydro International. The separated liquor is returned to the storage tank, being available for application on land. The fibrous fraction is thereafter dried to upgrade the DS content to 60-70%, ready for the PYREG slow pyrolysis process. Potential suppliers of dryers include Klein, Sevar and Cambi.



In addition to the ancillary equipment above, the following needs to be provided on site by external suppliers: electrical power 400V, 3ph 80A ; water supply ½’’, 4-10 bar, frost-proof, backflow of potable water); gas supply (LPG tank regulator with >15kg/hr, burner power 50-200 kW); exhaust chimney (minimum 200 mm diameter). Mechanical and electrical installation would be provided by local labour, supervised by PYREG GmbH in-house commissioning engineers, who would test and commission the plant and train operators in the UK. The commissioning phase is very important to enable PYREG GmbH to optimise the process parameters to suit particular feedstocks, ensuring the plant will run efficiently. Moreover, PYREG GmbH would ensure the quality of the biochar and emissions associated with the process. These are of importance for planning and permitting reasons, as explained in the next chapter.

4.0 Planning and permitting aspects This section lists some UK and EU legislation relevant to the installation of the PYREG technology at a food waste AD site and highlights legislation that applies to AD operations that may be affected by the integration of the pyrolysis process to AD. 4.1 Planning Permission AD installations accepting third-party waste need full planning permission. It is possible that the use of digestate in a PYREG system could be interpreted as a waste incineration activity, in which case the requirements of the Waste Incineration Directive and the perception of local communities should be considered. Operators interested in integrating the PYREG system to their processes, or project developers considering PYREG at the design stage, should contact their local planning authorities. 4.2 Environmental Permitting Regulations In England and Wales the use of food wastes at AD sites, the use of the resultant biogas and the storage and spreading of digestate are subject to the Environmental Permitting Regulations 2010 (SI2010 No.675) (EP)4. This regime regulates AD through Exemptions, Standard Rules Permits and Bespoke Permits mechanisms. Exemptions Exemptions are available for low-risk, small-scale activities where operators can register with the Environment Agency online and usually free of charge. Exemption T25 covers a range of wastes, including food wastes, at non-agricultural premises. Under this exemption storage and treatment is limited to 50 m3 at any one time and the burner is limited to a net thermal input of less than 0.4 MW. Digestate produced at AD plants operated under Exemption T25 can be used on agricultural land if it meets the requirements laid out by ‘U10 - Spreading waste on agricultural land to confer benefit’ or on non-agricultural land if it meets the requirements laid out by ‘U11 - Spreading waste on non- agricultural land to confer benefit’. Biochar is not listed under U10 or U11.

4 EP replaced the Pollution Prevention and Control and Waste Management Licensing regimes.

http://www.environment-agency.gov.uk/static/documents/Business/Anaerobic_Digestion_and_Environmental_Permitting.pdf

http://www.environment-agency.gov.uk/business/topics/permitting/116322.aspx





Standard Rules Permits Standard Rules Permits are available for defined operations the risks of which are considered by the EA to be well understood. Table 6 lists the activities permitted under SR2010 No.155, the set of Standard Rules Permits most relevant to food waste AD sites. It covers the treatment of digestates, including by mechanical (e.g. screening, centrifuge or pressing), chemical (e.g. addition of thickening agents) and physical (e.g. drying) means. As explained in section The UK industry now and into the future, processing would be required to upgrade the 3-7% DS content in the whole digestate to 60% in the dry digestate in preparation for the pyrolysis process.

Table 6: List of activities allowed under SR2010 No.15

R13: Storage of wastes pending the operations numbered R1, R3 and D10

Treatment of waste including shredding, sorting, screening, compaction, baling, mixing and maceration.

R3: Recycling or reclamation of organic substances that are not used as solvents

Digestion of wastes including pasteurisation and chemical addition.

Gas cleaning by biological or chemical scrubbing.

Gas storage and drying.

Treatment of digestate including screening to remove plastic residues, centrifuge or pressing, addition of thickening agents (polymers) or drying.

Composting and maturation of digestate.

The maximum throughput of animal wastes shall be <10 tonnes per day.

The total quantity of waste accepted at the site shall be less than 75,000 tonnes a year.

R1: Use principally as a fuel or other means to generate energy

The use of combustible gases produced as a by-product of the anaerobic digestion process as fuel.

Except for the auxiliary flare, the aggregate rated thermal input of all appliances used to burn biogas shall be less than 3 megawatts.

D10: Incineration on land

Use of an auxiliary flare required only for short periods of breakdown or maintenance of facility.

SR2010 No.15 states that there shall be no point source emissions to air, water or land, except from the sources and emission points listed in Table 7. Site operators would have to consider the permitting implications around the emissions arising from the combustion of syngas, including the limits set by the Waste Incineration Directive (WID).

5 Please note that SR2010 No.15 is for off –farm AD. There is a further Standard Rules permit for on-farm AD (SR2010 No.16)

but that is not covered herein due to the focus of this project being on food waste AD.

http://publications.environment-agency.gov.uk/PDF/GEHO1011BUIK-E-E.pdf




Table 7: Emission limits under SR2010 No.15 (by point and source)

Stacks on engines

Oxides of nitrogen 500 mg/m3

Carbon monoxide 1,400 mg/m3

Sulphur dioxide 350 mg/m3

Total volatile organic compounds (including methane) 1,000 mg/m3

Non-methane volatile organic compounds 75 mg/m3

Stacks on boilers burning biogas

Oxides of nitrogen No limit set

Carbon monoxide No limit set

Auxiliary flare

Oxides of nitrogen No limit set

Carbon monoxide No limit set

Pressure relief valves

Biogas No limit set

Emission levels at normal temperature and pressure and 5% O2.

SR2010 No.15 requires emissions from the activities to be free from noise and vibration at levels likely to cause pollution outside the site, unless the operator has used appropriate measures to prevent or where that is not practicable, to minimise, the noise and vibration. With PYREG no special attenuation will have to be considered to meet the max dB level of 80 at 1 metre. Bespoke permits Operators that cannot comply with the Standard Rules Permits available for AD must apply for a bespoke permit from the EA. The process requires operators to provide information on any criteria of the Standard Rules Permits that cannot be met and explain how they intend to control the risks associated with such activities. The EA is then required to go out to statutory consultation on Bespoke Permits. Under the Penfold ruling, the EA is typically required to determine an application within 13 weeks of it being deemed Duly Made. Charges are based on an operational risk appraisal that covers the complexity, inputs & emissions and location of projects as well as the operator’s management systems & performance. 4.3 Waste Incineration Directive The application of the PYREG technology to pre- and post-digestion screenings will most likely require compliance with WID. This has an impact on the cost of operating a PYREG plant at an AD site that hasn't got Environmental Permitting to include WID - possibly most of the AD plants in the UK. The extra costs involved would include: a) acquiring the permit; b) monitoring the equipment to prove compliance with the permit sampling; and c) reporting on the designated limits and safeguards. Combustion of the syngas in a flameless oxidation process (FLOX-firing) at about 1,250oC, controllable by a lambda regulated addition of air controlled by an adjustable air valve and combustion air, results in very low emissions (Figure 5). During the commissioning phase, PYREG adjusts the conditions of the pyrolysis process to suit particular feedstocks, to ensure




the quality of the syngas – e.g. minimise the potential for formation of Polycyclic Aromatic Hydrocarbons. So far the three companies using the PYREG system commercially have not fallen within the WID operating criteria 4.4 Animal By-Product Regulations Animal By-Products (ABPs) are animal carcases, parts of carcases or products of animal origin that are not intended for human consumption. The Animal By-Products Regulations permit approved biogas premises to treat low-risk (Category 3) ABPs and catering waste which contains meat or which comes from a premise handling meat. High risk (Category 2) ABPs cannot be used as feedstock in biogas plants, except where they have first been rendered to the 133°C/3 bar/20 minute EU pressure-rendering standards. The integration of the PYREG technology to an AD site is not expected to have implications on ABPR compliance. The proposed configuration would see only the fibrous fraction of digestate (post-digestion screenings or digestate cake6) being pyrolysed. Therefore, the liquid fraction of the digestate, which would be available for application to land, if produced from food wastes containing the feedstocks listed above, would need to be treated as per the requirements of the ABPR. 4.5 Duty of Care The Duty of Care requires all persons involved with the production, storage, transport and disposal of waste to take all reasonable steps to ensure it is handled in a safe way. In order to be stored appropriately and securely, the biochar receives a fine water spray to prevent self-ignition and should be stored in a bay or bays of a covered industrial building or barn. If the biochar produced from post-digestion screenings is classified as a waste (see section PAS 110 and the Quality Protocol for digestates), then appropriate permission for use on land must be obtained from the EA. AD plant operators would need to ensure the biochar is transported and handled by people or businesses that are authorised to do so and keep complete waste transfer notes as a record for at least two years. 4.6 Operator Competence The EA requires AD plants holding environmental permits to ensure sufficient competent persons and resources are available to manage and operate the activities permitted. According to the Regulatory Guidance on Operator Competence (RGN 5), the EA may consider operator competence at any time, whether as part of determining an application for a new or varied permit or throughout the life of the permit. During the commissioning phase PYREG would train operators on how to use the equipment, comply with relevant legislative requirements and minimise potential risks to the environment and human health. RGN 5 also requires staff at ‘relevant waste operations’ to have specific training in waste management and operators may need to present details of compliant individuals. There are currently two approved training schemes for England and Wales: the CIWM/WAMITAB Operator Competence Scheme, developed jointly by the Chartered Institution of Wastes Management (CIWM) and the Waste Management Industry Training and Advisory Board (WAMITAB); and the ESA/EU Sector Skills Scheme, developed jointly by the Environmental Services Association (ESA) and the Energy and Utility Sector Skills Council (EU Sector Skills).

6 Different terminologies are used here because the several types of ancillary equipment that can be adopted to dewater the

digestate (e.g. screw-press, centrifuge) produce slightly different materials (e.g. post-digestion screenings, digestate cake).

http://archive.defra.gov.uk/foodfarm/byproducts/documents/compost_guidance.pdf

http://www.businesslink.gov.uk/bdotg/action/detail?itemId=1097280893&r.i=1079432604&r.l1=1079068363&r.l2=1086048413&r.l3=1079431917&r.s=m&r.t=RESOURCES&type=RESOURCES

http://www.environment-agency.gov.uk/static/documents/Business/RGN_5_Operator_Competence.pdf

http://www.wamitab.org.uk/pg/competence

http://www.wamitab.org.uk/pg/competence

http://www.euskills.co.uk/waste-management/technical-competence/



4.7 Health and Safety Thorough hazard and risk assessments are required at AD sites given the flammable atmospheres, fire and explosion, toxic gases, confined spaces, pressure systems, COSHH and many other risks. Pyrolysis has similar H&S implications and hence similar Hazard and Operability Analysis would need to be conducted. The ATEX regulations (Directive 99/92/EC also known as 'ATEX 137' or the 'ATEX Workplace Directive' and Directive 94/9/EC also known as 'ATEX 95' or 'the ATEX Equipment Directive') would apply to the installation. A number of safety measures have been incorporated into the PYREG system, as outlined in section 3.1. AD operators should observe that biochar can contain Polycyclic Aromatic Hydrocarbons with a variety functional groups (Schmidt and Noack, 2000; Preston and Schmidt, 2006), which in certain quantities can be carcinogenic. The quality of the biochar being produced and stored on site would therefore need to be monitored. 4.8 PAS 110 and the Quality Protocol for digestates WRAP has supported the development of a Quality Protocol and Publicly Available Specification (PAS) for digestate to provide users with confidence that products conform to a methodology approved by regulators. PAS 110 and the Quality Protocol cover the whole digestate, as well as the fibre and the liquor separated. Because the use of digestates as a feedstock for biochar production is not covered in PAS 110 or in the Quality Protocol for digestates, biochar produced from PAS 110 digestate could be subject to EPR controls. Work is under way to support the development of a Biochar Risk Assessment Framework (BRAF), which is expected to work as a prelude for the development of a PAS and / or Quality Protocol for biochar. The initiative is led by the UK Biochar Research Centre and supported by a range of partners from academia, industry and not-for-profit organisations, including WRAP

7. Over the next two years, the Steering Group will compile and analyse current and available data on the risks associated with biochar production and deployment. The first challenge that the BRAF Steering Group is looking to address is the lack of an agreed definition for biochar, which is likely will cover the types of feedstocks that can and cannot be used for biochar production, in a similar way that PAS 100 defines what feedstocks can be used for composting processes. The limited availability of information on the risks and benefits of biochar produced from food waste digestates, unless addressed, could result in this type of feedstock not being listed as suitable for biochar production. The Steering Group has proposed a two-tier regulatory approach to prevent and minimize risks associated with biochar deployment (

7 Launched in January 2012, BRAF is funded by the Esmee Fairbairn Foundation (75%) with a contribution from the UK

Biochar Research Centre (25%) and supported by the Environment Agency, the Scottish Environment Protection Agency,

WRAP, the National Farmers Union, Newcastle University, Rothamsted Research and the Biochar Foundation.

http://www.environment-agency.gov.uk/static/documents/Business/AD_Quality_Protocol_GEHO0610BSVD-E-E.pdf



Figure 8). The first tier approach would consist of using a PAS-type methodology, with Maximum Permissible Limits (MPLs) used by British or EU national soil regulations, against which to compare biochar samples. In addition, the following potential contaminants are particular relevant in the context of biochar:

Heavy metals are conserved during volatilisation of associated organic molecules and in

majority will be present as ash within biochar. It may be possible to remove these

contaminants through selective removal of ash (Hwang et al. 2008) but elements such as

phosphorus and potassium are also present in the ash.

Polycyclic Aromatic Hydrocarbons (PAHs) can be formed from any carbonaceous

feedstock and risk of formation increases with the temperature and residence time of the

biomass conversion processes (Hwang et al. 2008; McGrath et al. 2001). Higher

molecular weight PAHs, such as Benzo[a]pyrene, are carcinogenic and their content in

food substances is strictly regulated.

Dioxins are produced when biomass is processed in the presence of chlorine or chlorine compounds when oxygen is available. Municipal Solid Waste (MSW) containing PVC could produce dioxins at levels of concern. PVC is unlikely to be present in source-segregated MSW and commercial food waste, and if present as contaminants, would probably be removed as part of the de-packaging process.



Figure 8: The two-tier approach proposed for biochar production and deployment

(As proposed by the Steering Group of the Biochar Risk Assessment Framework)

If compliant with the MPLs, the biochar would be certified and (if a waste) exempted from waste regulations. If the biochar produced did not pass the Tier-1 approach, it would be considered a waste or contaminated material. This would require the biochar producer and/or user to develop a contextualised risk assessment to understand the implications of using the material in a particular context, with the supervision of a regulatory agency.

TIER 1 APPROACH

Biochar production

Biochar analysis

Comparison of contaminant concentrations

vs. available MPL

By amount of biochar applied (mg of contaminant/Kg of

biochar)

PAS-certified biochar (exempted as waste)

By annual rate of addition (kg of

contaminant/hectare/year)

Complies with MPL?

TIER 2 APPROACH

Permit and monitoring

regime

Contextualised risk

assessment

Biochar is considered a waste

NO

YES



5.0 Benefits of the PYREG system in an AD setting This chapter discusses our main findings on the assessment of the financial and GHG and energy benefits of integrating the PYREG slow pyrolysis process to food waste AD plants in the UK. The analysis was complicated by the difficulty in accessing commercially sensitive data and the specificity and context of studies publicly available, as explained below. 5.1 Financial analysis If operated 24 hours per day, with a 120-180 kg/hr throughput range, the standard 500 kW PYREG unit would require between 2.9-4.3 tonnes of feedstock per day at 55-70% DS and energy content of 10 MJ/kg DS. As explained in detail in section The UK industry now and into the future, the smallest AD plant to serve the capacity of one standard 500 kW PYREG unit would be one that processes at least 30,000 tonnes per year of food waste. Such plant would typically have capacity to produce 3.6 m3 of dry digestate (60% DS). A 50,000 tpa plant would produce 5.99 m3 of dry digestate (60% DS), enough to run two PYREG units (each operating at 120kg/hr). Our study indicates that the capital and operational costs associated with EPR and WID compliance favour deployment of two PYREG units. The CAPEX8 of a 1MW PYREG project is just over £1M, installation costs are approximately £100k and annual operational costs are just under £170k (Table 8). Having two PYREG modules working together also confers savings in other areas. For instance, the CAPEX and installation costs for a dewatering screw-press are £36,000 to service one PYREG unit or £71,200 to service two units. The CAPEX and installation costs for a dryer (inc. heat exchanger equipment) to service one PYREG unit are £129,000, or £206,000 for a larger unit to feed two modules. As mentioned before, the PYREG process converts two thirds of the energy in the feedstock to syngas, which is combusted to generate heat to perpetuate the pyrolysis process and provide spare heat to dry the digestate. Therefore, the PYREG unit should not impose heavy energy penalties on the efficiency of AD plants. The quantity of spare heat generated from the pyro-reactors at 550oC varies depending on the biomass feedstock. An average of 161 kW has been observed by PYREG from tests with 9 different types of feedstock. This figure was reduced to 57% to give 92kW usable heat. Therefore, for 7,500 hours of operation the annual available heat from two PYREG units was taken to be 1,365,000 kWh. The value of the heat produced is not considered a saving in any of the financial models because it is consumed by the PYREG project – i.e. to prepare the feedstock and perpetuate the pyrolysis process. For that same reason, it is not certain whether the heat would qualify for the Renewable Heat Incentive. Two different models of revenue and savings for a project with two 500 kW PYREG units are presented (Table 9 and Table 12), to illustrate the impact of such uncertainties on the commercial viability of the project. The models are based on an operation of 7,500 hours per year. As shown in Table 8, the annual electricity charge consumption of a two-module PYREG project operating for 7,500 hours would be 450,000 kWh, which at £0.12/kWh would cost £54,000. An option to use a Rankine cycle engine to generate electrical power rated at 19kW from the first stage heat leaving the pyro-reactors is anticipated to be available by mid 2013 and has been included in both models. Operating two PYREG units for 7,500 hours

8 The prices in GBP for the PYREG unit and for the drying equipment are based on a conversion rate of GBP 1 = EUR 1.21.



per annum would make available 285,000 kW of electricity. That would reduce the cost of buying electricity for use on the site by £34,200 per annum. If the PYREG system qualifies for renewable energy incentives, the Net Present Value (NPV) of the project is £433,801 and the Internal Rate of Return (IRR) is 20% (Table 11). Without the incentives, the NPV is reduced to £152,745 and the IRR to 14% (Table 14). The net annual cash-flow is positive from Year 2 for the two models. When the incentives are available, the cumulative cash-flow including the cost of finance is positive from Year 7 (Table 10), whilst without the incentives it only becomes positive form Year 9 (Table 13). As discussed in section Biochar in horticultural products, biochar is attracting from €390 to €600 per tonne in Germany, Switzerland & Austria and £600 per tonne for R&D applications in the UK. At £4009 per tonne, as assumed in the model, it is expected the biochar would be destined to higher value horticultural applications. The extent to which the value for biochar can be realised will depend on the product meeting the requirements of the end-of-life regulations. As discussed before (PAS 110 and the Quality Protocol for digestates), a PAS and/or Quality Protocol for biochar are expected to become available in approximately two years. The financial case for deployment of the PYREG unit at food waste AD sites depends heavily on being able to demonstrate the safety and suitability of biochar from digestates for horticultural applications.

9 WRAP notes that the price given is for “clean” i.e. uncontaminated biochar made from wood in a closely controlled environment. The biochar being proposed is unlikely to command anything like such prices in the short/medium term. Also, the rates are retail figures, which tend to be several times raw material input values. The

The case for the PYREG slow pyrolysis process in improving the efficiency and profitability of Anaerobic Digestion plants in the UK 34

Table 8: Estimated CAPEX, installation costs and OPEX for a two-module PYREG project

Expenditure CAPEX (GBP) Installation (GBP) OPEX (GBP)

Two 500kW PYREG units ex-works Germany* 446,281

FAN/Bauer dewatering screw-press + feed tank + platform+ pump + pipework + ancillaries 61,200

Klein digestate dryer + heat exchanger equipment* 206,000

Delivery to UK Site 9,000

Site Foundations + building + drainage + covered biochar storage bay 80,000

Power Supply (3ph 400V 80A) 4,000

800 litre LPG gas tank set (for process start up) 2,000

Clean water supply to provide 80 litres per hour 1,000

Feedstock hopper to hold 3 days supply of digestate @55-60% DS 10,500

Conveyer/elevators to feed dryer+ lift feed stock to PYREG supplied feed in bin 12,000

Two elevators to load skips 6,000

20m x 15m concrete apron e.g. mixing area for product to be mixed with compost 5,000

Two Ranking engines to each generate 19kW of electricity (available from 2013) 85,000

Part use of front end loader @ £192/week 10,000

Four skips for biochar 8,000

Labour cost to install facility (4 men each costing £800 per week for 6 weeks) 19,200

Planning approval (£10k) EA + consultant EP fees (£45k) 55,000

WID monitoring equipment + installation (sensors located around the plant and in the chimney all connected to the SCADA electronics) 75,000

Testing + commissioning cost (£1650/wk for 3 weeks) 4,950

Contingency allowance for installation phase 10,000

12 month operating labour cost allow 1/2 of a technician employment cost 21,000

Testing and Analysing costs + EP Compliance costs (£1000/month) 12,000

LPG gas costs (30 litres each time unit is restarted, allow for 4 restarts/week, £0.50/litre) 2,880

Annual electricity charge 7500 (hours) x 60kW (demand) x £0.12/kWh 54,000

Annual water and sewerage (80 litre / hr x 7500 hours = 600,000 litres per year = 600 cubic metres x £3) 1,800

Annual business rates 5,500

Annual servicing & maintenance costs (5% of main equipment CAPEX £906,981) 45,350

General overheads (insurance and management @1.5% of total CAPEX (£1,076,981) 15,030

Cost of feedstock supply (assumed to be nil due to being a waste) 0

** TOTAL 1,001,981 98,150 167,560

*The exchange rate applied is GBP1 = EUR1.21

** Costs exclude land to establish facility, VAT & any other taxes


Table 9: Annual revenues and savings for a PYREG project with RHI and FIT

Revenue Quantity Unit Value (£) Value (£)

Biochar (tonnes) 660 400 264,000

Usable Heat Renewable Heat Incentive [RHI] (kWhth) 1,365,000 0.03 40,950

Electricity feed in tariff [FIT] (kWhel) 285,000 0.035 9,975

Savings & Added Value

Electricity (kWhel) 285,000 0.12 34,200

TOTAL 349,125

Table 10: Ten year cash-flow forecast for a PYREG project with RHI or FIT

Cashflow table (£) Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10

CAPEX -1,076,981

107,698

Installation costs -98,150

Annual maintenance costs (with inflation)

-45,350 -46,711 -48,112 -49,555 -51,042 -52,573 -54,150 -55,775 -57,448

Annual operating costs (with inflation) -126,935 -130,743 -134,665 -138,705 -142,866 -147,152 -151,567 -156,114 -160,797 -165,621

Total cash outflow -1,302,066 -176,093 -181,376 -186,817 -192,421 -198,194 -204,140 -210,264 -216,572 -115,371

Annual income (with inflation) 349,125 366,581 384,910 404,156 424,364 445,582 467,861 491,254 515,817 541,607

Net annual cashflow -952,941 190,488 203,535 217,339 231,942 247,388 263,721 280,990 299,245 426,237

Annual financing cost -91,145 -77,810 -63,563 -48,349 -32,113 0 0 0 0 0

Cumulative cashflow exc financing cost -952,941 -762,452 -558,917 -341,578 -109,636 137,752 401,473 682,463 981,708 1,407,944

Cumulative cashflow inc financing cost -1,044,085 -931,407 -791,435 -622,446 -422,617 -175,229 88,492 369,482 668,727 1,094,964

Table 11: NPV and IRR for a PYREG project with RHI and FIT

Net Present Value £433,801

Internal Rate of Return 20%


Table 12: Annual revenue and savings for a PYREG project without RHI or FIT

Revenue Quantity Unit value (GBP) Value (GBP)

Biochar (tonnes) 660 400.00 264,000.00

Savings

Electricity (kWhel) 285,000 0.12 34,200.00

TOTAL 298,200.00

Table 13: Ten year cash-flow forecast for a PYREG project without RHI or FIT

Cash-flow table (£) Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10

CAPEX -1,001,981

100,198

Installation costs -98,150

Annual maintenance costs (with inflation)

-45,350 -46,711 -48,112 -49,555 -51,042 -52,573 -54,150 -55,775 -57,448

Annual operating costs (with inflation) -122,210 -125,876 -129,652 -133,542 -137,548 -141,675 -145,925 -150,303 -154,812 -159,456

Total cash outflow -1,222,341 -171,226 -176,363 -181,654 -187,103 -192,716 -198,498 -204,453 -210,586 -116,706

Annual income (with inflation) 298,200 313,110 328,766 345,204 362,464 380,587 399,617 419,597 440,577 462,606

Net annual cash-flow -924,141 141,884 152,403 163,550 175,361 187,871 201,119 215,145 229,991 345,900

Annual financing cost -85,564 -75,632 -64,964 -53,515 -41,240 -28,089 0 0 0 0

Cumulative cash-flow exc financing cost -924,141 -782,257 -629,854 -466,304 -290,943 -103,072 98,046 313,191 543,182 889,082

Cumulative cash-flow inc financing cost -1,009,705 -943,453 -856,014 -745,979 -611,858 -452,076 -250,958 -35,813 194,178 540,078

Table 14: NPV and IRR for a PYREG project without RHI or FIT

Net Present Value £152,745

Internal Rate of Return 14%



5.2 GHG and energy analysis A comparative streamlined lifecycle assessment approach was applied to estimate the relative greenhouse gas (GHG) abatement10 and energy use benefit of three scenarios:

Treating digestates from anaerobic digestion of feedstocks in combination with a PYREG unit to produce a more recalcitrant form of carbon for sequestration.

Using the same feedstocks for anaerobic digestion only.

Using the same feedstocks with a pyrolysis unit only.

The functional unit adopted for assessment of the energy benefits and GHG abatement of each technology scenario was 1 tonne of feedstock as received (i.e. at typical moisture content). The assumptions on which this analysis is based are explained in Appendix A. Primary data to support the GHG and energy assessments was not accessible from AD plants. Energy requirements and yields for single feedstock AD plants were derived instead from a peer reviewed published study of energy use in German AD plants and technology (Poeschl et al. 2010) and a subsequent lifecycle assessment (2012a, 2012b). Where data gaps occurred, other literature sources were consulted. Estimated drying energy requirements were provided by Klein GmbH. PYREG supplied a theoretical model of the pyrolysis unit which was subsequently modified for the purposes of this assessment. Figure 9 shows the comparative GHG abatement potential of the 3 technology scenarios per tonne of feedstock and within the assumptions and boundaries of the assessment. The results are not absolute GHG emissions and should only be used for indicative comparisons between each technology scenario, not between feedstocks. A more appropriate presentation with respect to the goal is to normalise the results with respect to the AD GHG abatement as shown in Figure 10. For the goal of comparative assessment the figures do not account for reference cases for feedstocks, i.e. emissions net of what would occur if the feedstock were not to be used by the technology.

10 GHG emission assessment is a more adequate interpretation for carbon assessment, therefore GHG assessment and carbon

assessment is used here interchangeably. As part of this assessment we limit the scope of the carbon assessment to

modelling the emissions and removals of greenhouse gases carbon dioxide, methane and nitrous oxide. The global

warming impact is reported throughout in kg of carbon dioxide equivalents (kgCO2eq) using Kyoto global warming

potentials which are published in the IPCC’s second assessment report to report.



Figure 9: Comparative GHG abatement potential of the 3 technology scenarios

Figures are kg CO2eq per tonne of feedstock for different data sources for AD of food waste and biodegradable

fractions of Municipal Solid Waste.

Figure 10: Relative estimated GHG abatement of the three scenarios normalised

(The AD scenario being 100%)

The energy balances (Figure 11) show that for wet feedstocks AD is mostly the best scenario within the assumptions made by the assessment (heat energy is captured from AD biogas CHP and exported for use along with electricity as assumed the carbon assessment). Unlike the carbon assessment, the results of the energy balances do not account for the

-300

-250

-200

-150

-100

-50

0

food residue MSW food waste source segregated

AD

AD + Pyrolysis

Pyrolysis only

0%

20%

40%

60%

80%

100%

120%

140%


AD

AD + Pyrolysis

Pyrolysis only



impact of biochar generated; the material has an energy content but is not considered to be recovered in this assessment - it is assumed to be used for land spreading instead.

Figure 11: Estimated MJ energy balances of the three technology scenarios

Positive values mean net energy deficit, negative figures mean net energy yield. The estimation is based only on

energy used within the plant boundary and does not account for offsite primary energy for electricity generation

and fuel production and distribution. 1 MJ of consumed electricity is equivalent to 1 MJ of heat energy for the

purposes of this assessment.

The lower estimated energy balance for pyrolysis of MSW digestate is negative compared to other food wastes (Table 15). This is largely due to the parameters assumed for the digestate and feedstock, most notably the relatively high ash content. This results in no net energy yield for pyrolysis of MSW waste and digestate. The added burden for MSW digestate is the additional drying requirements and dry matter losses per original tonne of feedstock.

Table 15: Comparative energy balance of the three technology scenarios

1 tonne reference feedstock (as received) AD AD + PYREG PYREG

Food residue -1291 -1053 23

MSW -1681 447 316

Food waste source segregated -1689 -1741 37

Positive values mean net energy deficit, negative figures mean net energy yield. Not absolute figures.

These figures are derived with crude assumptions that have not been substantiated and therefore may be wholly unrealistic for pyrolysis of MSW and digested organic fractions of MSW. Efforts to obtain more realistic data from the literature and experts were not

-2000

-1500

-1000

-500

0

500

1000


AD

AD + Pyrolysis

Pyrolysis only

Net energy balance MJ per tonne of

feedstock as received



successful. This aspect of the assessment was severely limited by the lack of available empirical data characterising both the initial feedstock and its subsequent digestate composition, and respective measured performance data from the PYREG system. Only the source-segregated food waste results use laboratory test data of actual digestate calorific value to estimate PYREG yield. The food residue and MSW energy and biochar yields are estimated using crude assumptions of the digestate calorific value and carbon content. For example the carbon yield for MSW and food residue is the same for the same dry matter content due to the assumptions made Table 16. This is an artefact of the ash and C content (which differ between the assumed carbon content of MSW and food residue digestates, but both have blanket conversion factor for carbon yield from that which enters the pyrolyser). The source segregated screenings carbon yield is at least based on measurements of carbon content of a sample of recovered solids, but again this has the same blanket conversion factor applied to estimate the biochar carbon yield.

Table 16: Pyrolyser outputs per tonne of AD original feedstock

DM out /

original tonne

feedstock

kg C yield / tonne using

PYREG model

kg C per tonne

dm content

digestate

NET C yield kg

Food residue 36.0 88 125 5

MSW 286.2 88 125 36

Source segregated food waste 61.9 213 305 19

Yields are for kg C / tonne of feedstock estimated for digestate @70% DM and various CV, ash, etc.

However, the benefits of pyrolysing solids screened from digestate are likely to be sensitive to the assumptions on the efficiency of the technologies applied for capturing solids. For instance, a UK food waste AD plant from which data was obtained captures only 3 tonnes of solids (at 60% moisture) per approximately 80 tonnes of feedstock. The biochar yield per tonne of food waste feedstock digested, with existing screening solids capture rate, would only give under 5 kg carbon, or under 15 kg CO2eq abatement (over 100 years with 20% losses if soil spread). This assessment assumes a much greater capture rate, based on consultation with suppliers of alternative ancillary equipment. Estimates could not be given for the energy and carbon impact of the AD site’s current screening process if these solids were to be pyrolysed since data on plant operation and screw-press energy requirements were not available. Although with the existing capture efficiency the benefit per original tonne of feedstock would not make the application of PYREG appear as beneficial from a carbon sequestration perspective, actual operational data would be required to evaluate the site specific carbon and energy benefits. The fate of the carbon in the fibrous fraction of food waste digestate that is actually spread to agricultural soils is assumed to return to the atmosphere within the 100 year time period due to the carbon turnover of the soil. However some proportion of the more recalcitrant fractions may be retained in soils and the impact of this fraction in soils should be looked at in more detail to ascertain the true net impact of converting this fraction into biochar.



6.0 Conclusions This study confirmed the feasibility of using post-digestion screenings to produce biochar using the PYREG technology and that many food waste AD operators face costs associated with the disposal or storage of digestate.

With voluntary targets to phase out the 3M m3 of peat used in growing media and soil

improvers by 2030, year-on-year reductions of around 200,000 m3 of peat, equivalent to

an annual rate of reduction (in volume) of 10%, needs to be delivered by the

horticultural industry.

Technical and supply chain issues associated with alternatives to peat have led to a

search for new feedstocks for growing media formulations and recent success with

biochar in the amateur gardeners sector has led to this material attracting interest from

other segments of the horticultural sector.

The literature suggests that biochars could be valuable components in growing media formulations, but few studies focused on biochars from digestates - and none of those focused on biochar from food waste digestate.

It has been shown that biochars can manipulate the quality of soils and support soil biota

and plant growth, but the properties of biochar vary considerably depending on the

feedstocks and thermochemical processes used in its manufacture and few studies have

looked at biochars from digestates.

The three studies found on the properties of biochars produced from digestates indicate

that AD prior to pyrolysis increased some beneficial properties. AD prior to pyrolysis did

not have all of the same effects on the feedstocks tested hence there is a clear

requirement for practical experimentation in this area.

Cost of supply is an important factor to be taken into account and further information is needed on the costs that could be absorbed by the horticultural industry if gains could be realised from addition of biochar to growing media.

The costs of producing, transporting, storing and delivering biochar to fields in the UK

has been estimated at £0-£200 per tonne (if produced from residues) to £430 per tonne

(if produced from virgin biomass).

Our market research indicates that biochar produced from high-quality feedstocks is

being supplied at £600 per tonne in the UK for research and development, though for

commercial applications the value attracted at wholesale point is possibly lower.

Our mar et research shows that European prices vary from €685 per tonne in

Switzerland) for research and development to €390 per tonne (in Austria) for application

on agricultural land (maxed with animal manure).

The CAPEX, installation costs and OPEX associated with EPR and WID compliance favour deployment of two 500 kW PYREG modules, for which: CAPEX11 would be £1M, installation costs would be £100K and OPEX would be £170K.

11 Based on an exchange rate GBP1=EUR1.21.



If the heat generated from the syngas combustion and used to perpetuate the pyrolysis

process and dry the feedstock were to qualify for RHIs and the electricity generated with

the spare heat were to qualify for FITs, then the NPV of a 1MW PYREG project would be

£433,801 and the IRR would be 20%.

Without the renewable-energy incentives, the NPV would be reduced to £152,745 and

the IRR to 14% - and that is a risk given that the heat is used to perpetuate the pyrolysis

process or dry the feedstock in preparation for pyrolysing.

The net annual cash-flow for a 1MW PYREG project would be positive from Year 2

regardless of incentives. With incentives available, the cumulative cash-flow including the

cost of financing is positive from Year 7, whilst without the incentives it only becomes

positive form Year 9.

A 1 MW PYREG project would have the capacity to produce 600-900 tonnes of biochar per year.

The extent to which the value for biochar can be realised will depend on the product

meeting the legislative requirements for use in horticulture, which, for biochar from food

waste digestate, currently means going through the EP process.

Over the next two years the Biochar Risk Assessment Framework will be devising a

definition for biochar, which will possibly specify which types of feedstocks are suitable

for specific applications, and suggesting an appropriate regulatory approach to minimise

the risks associated with the production and deployment of biochar.

The BRAF assessment will be based on current and available information about biochar. For digestates from food waste not to be overlooked as a potential feedstock for biochar production, the lack of information on the safety and suitability of that type of biochar needs to be addressed. That is the aim of phase 2 of this DIAD project. There will be significant barriers to market should this information be lacking.



7.0 References

AEA, ADAS (2011) Implementation of AD in England & Wales – Balancing optimal outputs with minimal environmental impacts. Project reference FFG 1001 / R & D Contract Reference AC0409 DEFRA. Arnold, R., C. J. Banks, et al. (2010) Biowaste Digester Demonstration Project - Biocycle South Shropshire ltd. Final Report to DEFRA. Asai H., Samson B.K., Stephan H.M., Songyikhangsuthor K., Inoue Y., Shiraiwa T., Horie T. (2009) Biochar amendment techniques for upland rice production in Northern Laos: soil physical properties, leaf SPAD and grain yield. Field Crops Res 111:81–84. Atkinson C.J., Fitzgerald J.D., Hipps N.A. (2010) Potential mechanisms for achieving agricultural benefits from biochar application to temperate soils: a review. Plant Soil, 337:1–18. Banks, C. J., M. Chesshire, et al. (2010) Anaerobic digestion of source-segregated domestic food waste: Performance assessment by mass and energy balance. Bioresource Technology 102(2): 612-620. Banks, C. and Y. Zhang (2010). Optimising inputs and outputs from anaerobic digestion processes - technical report. WR0212 DEFRA. Bagreev A., Bandosz T.J., Locke D.C. (2001) Pore structure and surface chemistry of adsorbents obtained by pyrolysis of sewage sludge-derived fertilizer. Carbon 39:1971–1979. Blackwell P., Riethmuller G., Collins M. (2009) Biochar application for soil. Chapter 12 in Biochar for Environmental Management: Science and Technology. Lehmann J., Joseph S., Eds (Earthscan, London), pp 207–226. Berglund LM, DeLuca TH, Zackrisson TH (2004) Activated carbon amendments of soil alters nitrification rates in Scots pine forests. Soil Biol Biochem 36:2067–2073. Cao, X.D., Harris, W. (2010) Properties of dairy-manure-derived biochar pertinent to its potential use in remediation. Bioresource. Technol. 101 (14), 5222–5228. Chan K.Y., Xu Z. (2009) Biochar: nutrient properties and their enhancement. Chapter 5 in Biochar for Environmental Management: Science and Technology. Lehmann J., Joseph S., Eds (Earthscan, London), pp 67–84. Clarholm M. 1994 Granulated wood ash and a ‘N-free’ fertilizer to forest soil: effects on P availability. For Ecol Manage 66:127–136. Defra (2009) Availability and supply of alternative materials for use in growing media to meet the UKBAP target on reduced peat use in horticulture (SP08019). Research Project Final Report. Defra (2010a) Monitoring the horticultural use of peat and progress towards achievement of the UKBAP target (SP08020). Research Project Final Report.



Defra (2010b) Consultation on reducing the horticultural use of peat in England. Available at: http://archive.defra.gov.uk/corporate/consult/peat/101217-peat-condoc.pdf. Defra (2010c) Accelerating the uptake of Anaerobic Digestion in England: An Implementation plan. Dumroese R.K., Heiskanen J., Englund K., Tervahauta A. (2011) Pelleted biochar: Chemical and physical properties show potential use as a substrate in container nurseries. Biomass and Bioenergy 35: 2018-2027. Downie A., Crosky A., Munroe P. (2009) Physical properties of biochar, in Biochar for Environmental Management: Science and Technology. Lehmann J., Joseph S., Eds (Earthscan, London), pp 13–32. Erickson, C. (2003) Historical ecology and future explorations, in Amazonian Dark Earths: Origin, Properties, Management. Lehmann J., Kern D.C., Glaser, Woods W.I., Eds. (Dordrecht, Kluwer Academic Publishers) pp. 455–500. Gaunt J., Lehmann J. (2008) Energy balance and emissions associated with biochar sequestration and pyrolysis bioenergy production. Environmental Science and Technology 42: 4152-4158. Glaser, B., Haumaier, L., Guggenberger, G. and Zech, W. (2001) The Terra Preta phenomenon – A model for sustainable agriculture in the humid tropics. Naturwissenschaften 88:37–41. Glaser B., Amelung W. (2003) Pyrogenic carbon in native grassland soils along a climosequence in North America. Glob Biogeochem Cycles 17:1064. doi:10.1029/2002GB002019. Glaser, B. (2007) Pre-historically modified soils of central Amazonia: a model for sustainable agriculture in the twenty-first century. Phil. Trans. R. Soc. B 362:187-196. Hamer U., Marschner B., Brodowski S., Amelung W. (2004) Interactive priming of black carbon and glucose mineralization. Org. Geochem. 35: 823–830. Hammond J., Shackley S., Sohi S. P. and Brownsort P. A. (2011) Prospective life cycle carbon abatement for pyrolysis biochar systems in the UK. Energy Policy 39, 2646-2655. Hossain M.K., Strezov V., Chan K.Y., Nelson P.F. (2010) Agronomic properties of wastewater sludge biochar and bioavailability of metals in production of cherry tomato (Lycopersicon esculentum). Chemosphere 78:1167-1171. Ibarrola, R., et al. (2011) Pyrolysis biochar systems for recovering biodegradable materials: A life cycle carbon assessment. Waste Management, doi:10.1016/j.wasman.2011.10.005. Lukehurst, C., P. Frost, et al. (2010) Utilisation of digestate from biogas plants as biofertiliser. IEA Bioenergy Task 37. International Energy Agency. ILCD (2010) ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance. International Lifecycle Database. Joint Research Centre, IES. Brussels, European Commission.

http://archive.defra.gov.uk/corporate/consult/peat/101217-peat-condoc.pdf



Ishii T., Kadoya K. (1994) Effects of charcoal as a soil conditioner on citrus growth and vesicular-arbuscular mycorrhizal development. Journal of Japanese Society of Horticultural Science 63:529–535. Kim J. S., Sparovek G., Long R. M., De Melo W. J., Crowley D. (2007) Bacterial diversity of terra preta and pristine forest soil from the Western Amazon. Soil Biol Biochem 39:684–690. Kimura R., Nishio M. (1989) Contribution of soil microorganism to utilisation of insoluble soil phosphorus by plants in grasslands. In: Proceedings, 3rd Grassland Ecology Conference, Banska Bystrica, Czechoslovakia, pp 10–17. Laine J., Simoni S., Calles R. (1991) Preparation of activated carbon from coconut shell in a small scale cocurrent flow rotary kiln. Chem Eng Commun 99:15–23. Lehmann J., Kern D., German L., McCann J., Martins G.C., Moreira L. (2003) Soil fertility and production potential. Chapter 6. In: Lehmann J, Kern DC, Glaser B, Woods WI (eds) Amazonian dark earths: origin, properties, management. Kluwer Academic, Dordrecht, pp 105–124. Lehmann J., Gaunt J., Rondon M. (2006) Bio-char sequestration in terrestrial ecosystems – a review. Mitigation and Adaptation Strategies for Global Change 11: 403–427. Lehmann J., Joseph S. (2009) Biochar for Environmental Management: An Introduction in Biochar for Environmental Management: Science and Technology. Lehmann J., Joseph S., Eds (Earthscan, London), pp. 1-11. Lehmann J., Rondon M.A. (2005) Bio-char soil management on highly weathered soil in the humid tropics’. Chapter 36. In: Uphoff N (ed) Biological approaches to sustainable soil systems. CRC, Boca Raton, pp 517–530. Liang B., Lehmann J., olomon D., Kinyangi J., Grossman J., O’Neill B., jemstad J. O., Thies J., Luizao F. J., Peterson J., Neves E. G. (2006) Black carbon increases cation exchange capacity in soils. Soil Sci Soc Am J 70:1719–1730. Mahmood S., Finlay R. D., Fransson A. M., Wallander H. (2003) Effects of hardened wood ash on microbial activity, plant growth and nutrient uptake by ectomycorrhiza spruce seedlings. FEMS Microbiol Ecol 43:121–131. Major J., DiTommaso A., German L. A., McCann J. M. (2003) Weed population dynamics and management on Amazonian dark earth. Chapter 22 in Lehmann J, Kern DC, Glaser B, Woods WI (eds) Amazonian dark earths origin properties management. Kluwer Academic, Dordrecht, pp 125–139. Meyer-Aurich, A. et al. (2012) Impact of uncertainties on greenhouse gas mitigation potential of biogas production from agricultural resources. Renew. Energy 37 (1), 277. Mikan C. J., Abrams M. D. (1995) Altered forest composition and soil properties of historic charcoal hearths in southeastern Pennsylvania. Can. J. Forest Res. 25:687–696. Mueller, J., Boldrin A., et al. (2009) Anaerobic digestion and digestate use: accounting of greenhouse gases and global warming contribution. Waste Management & Research 27(8): 813-824.



Neves, E. G., Bartone, R. N., Petersen, J. B., Heckenberger, M. J. (2001) The timing of Terra Preta formation in the central Amazon: new data from three sites in the central Amazon, in Amazonian dark earths: explorations in space and time. Glaser B., Woods W.I., Eds (Springer) pp. 125-134. Pieti inen J., Kii il O., ritze . 000 Charcoal as a habitat for microbes and its effect on the microbial community of the underlying humus. Oikos 89:231–242. Poeschl, M., Ward S., et al. (2010) Evaluation of energy efficiency of various biogas production and utilization pathways. Applied Energy 87(11): 3305-3321. Poeschl, M., Ward, S., Owende, P. (2012) Environmental impacts of biogas deployment Part I: life cycle inventory for evaluation of production process emissions to air. Journal of Cleaner Production 24 (0), 168. Preston C.M., Schmidt M.W.I (2006) Black (pyrogenic) carbon: a synthesis of current knowledge and uncertainties with special consideration of boreal regions. Biogeosciences 3:397–420. Rehl, T. and Mueller, J. (2011) Life cycle assessment of biogas digestate processing technologies. Resources, Conservation and Recycling 56(1): 92-104. Rondon M.A., Lehmann, J., Ramirez, J., Hurtado, M. (2007) Biological nitrogen fixation by common beans (Phaseolus vulgaris L) increases with bio-char additions. Biol Fertil Soils 43:699–708. Sabine C. L. et al. (2004) in The Global Carbon Cycle: Integrating Humans, Climate, and the Natural World. SCOPE 62, Field C.B., Raupach M.R., Eds. (Island Press, Washington), pp. 17–44. Schmidt M. W. I., Noack A.G. (2000) Black carbon in soils and sediments: analysis, distribution, implications and current challenges. Glob Biogeochem Cycles 14:777–793. Spokas K. A., Reicosky D. C. (2009) Impacts of sixteen different biochars on soil greenhouse gas production. Ann Environ Sci 3:179–193. Solomon D., Lehmann J., Thies J., Schafer T., Liang B., Kinyangi J., Neves E., Peterson J., Luizao F., Skjemstad J. (2007) Molecular signature and sources of biochemical recalcitrance of organic C in Amazonian Dark Earths. Geochim Cosmochim Acta 71: 2285–2298. Sombroek, W., Ruivo, M.L., Fearnside, P.M., Glaser, B. and Lehmann J. (2003) Amazonian Dark Earths as carbon stores and sinks, in Amazonian Dark Earths: Origin, Properties, Management. Lehmann J., Kern D.C., Glaser, Woods W.I., Eds., (Dordrecht, Kluwer Academic Publishers) pp. 125–139. Steiner C., Glaser B., Teixeira W. G., Lehmann J., Blum W. E. H., Zech W. (2008a) Nitrogen retention and plant uptake on a highly weathered central Amazonian Ferraisol amended with compost and charcoal. J Plant Nutr Soil Sci 171:893– 899. Steiner C., de Arruda M. R., Teixeira W. G., Zech W. (2008b) Soil respiration curves as soil fertility indicators in perennial central Amazonian plantations treated with charcoal, and mineral or organic fertilisers. Trop Sci. doi:10.1002/ts.216.



Tambone, F., Scaglia, B. et al. (2010) Assessing amendment and fertilizing properties of digestates from anaerobic digestion through a comparative study with digested sludge and compost. Chemosphere 81(5): 577-583. Thies J. E., Rillig M. C. (2009) Characteristics of biochar: biological properties. Chapter 6. In: Lehmann J, Joseph S (eds) Biochar for environmental management science and technology. Earthscan, London, pp 85–10. Troeh F. R., Thompson LM (2005) Soils and soil fertility, 5th edn. Blackwell, Iowa. Trompowsky P.M., Benites V.M., Madari B.E., Pimenta A.S., Hockaday W.C., Hatcher P.G. (2005) Characterisation of humic like substances obtained by chemical oxidation of eucalyptus charcoal. Org Geochem 36:1480–1489. Tyron, E. H. (1948) Effects of charcoal on certain physical, chemical and biological properties of forest soils. Ecol Monogr 18:82–115. Van Zwieten L., Singh B., Joseph S., Kimber S., Cowie A., Chan K. Y. (2009) Biochar and emission of non-CO2 greenhouse gases from soil. Chapter 13 in Lehmann J, Joseph S (eds) Biochar for environmental management science and technology. Earthscan, London, pp 227–249. Vitasari, C. R., Jurascik, M. et al (2010) Exergy analysis of biomass-to-synthetic natural gas (SNG) process via indirect gasification of various biomass feedstock. Energy 36(6): 3825-3837. Verrue, V. (2011) NIEUWE BIOKATALYSE VOOR UPGRADING VAN DEELSTROMEN IN DE BIORAFFINADERIJ. MSC thesis. Available at: http://lib.ugent.be/fulltxt/RUG01/001/789/936/RUG01-001789936_2012_0001_AC.pdf. Warnock D. D., Lehmann, J., Kuyper T. W., Rillig M. C. (2007) Mycorrhizal responses to biochar in soil—concepts and mechanisms. Plant Soil 300:9–20. Woolf D. (2008) Biochar as a soil amendment: a review of the environmental implications. http://orgprints.org/13268/01/ Biochar_as_a_soil_amendment_-_a_review.pdf WRAP. 2009. Household food and drink waste in the UK. Food waste in schools. WRAP. 2010. Waste arising in the supply of food and drink to households in the UK. WRAP. 2012. Anaerobic digestion infrastructure in the UK. Zimmerman A. R. (2010) Abiotic and microbial oxidation of laboratory-produced black carbon (biochar). Environmental Science & Technology 44:1295–1301.



Appendix A - Assumptions of the GHG and

energy analysis

1.0 Reference systems The stated goal was to compare the relative GHG and energy merits of the three technology scenarios for each individual feedstock type, but not to compare the absolute merits of using different feedstocks, or comparative benefits of different feedstocks between different systems. Consequently, the estimates of emissions for each system do not take into account the net or marginal difference of GHG emissions or energy use that would occur from the existing fate of 1 tonne of feedstock, i.e. if it were not to be used in one of the three systems. There are a number of reasons for this: 1. Where a comparative assessment of GHG abatement potential of treating waste with

the three technology scenarios is required within a short time period, – a streamlined evaluation of the relative emissions for all three scenarios is a less intensive task.

2. The absolute emissions compared to a reference case for each feedstock is not necessary for the goal of the assessment because arguably the reference case for feedstock production and disposal when comparing the three scenarios is identical.

3. Identification of a clear reference system for food waste is complex. WRAP assumes landfill disposal is the alternative reference system for the fate of organic waste arisings. However as part of this assessment it appears that the evidence to support this as the standard reference situation is unclear12.

2.0 Exclusion of infrastructure, maintenance and capital equipment The impacts from the production, manufacture and transport of plant machinery are not included in this streamlined assessment, both for the fabrication of the technologies themselves or in the secondary data used to estimate the production and supply of materials. In these respects it is important to emphasise that the results reported here cannot be used to represent absolute GHG impact of the systems. Therefore the results cannot be used to compare with other assessments that have a different decision making context, boundaries and respective assumptions – for example in the wider sphere of waste and resources policy. In order to carry out an assessment to understand the impacts of changing treatment of waste resource to either of the three scenarios on a wider scale, a much more detailed analysis of the net consequences should be conducted – including direct and any indirect impacts of changing marginal demands on infrastructure, agriculture, transport and material consumption.

12 Data collected from local authorities (Wasteflow data) suggests that around 20% of MSW is sent to composting or AD. A

recent survey on the composition of household waste in Scotland, commissioned by Zero Waste Scotland, shows that 18%

of collected household waste is organic food waste and a further 12% is green waste. So it may be reasonable to suggest

that the reference alternative to AD should not be entirely disposed of into landfills. More likely it is an increasing mixture

of home, centralised composting and other organic waste treatment assessment of the impact of AD. The food and

organic waste arisings from commercial and industry sources may also affect the reference scenario – however robust data

on the disposal routes of these arisings in the UK were unavailable.



3.0 Feedstock parameters Though AD plants may co-digest a number of feedstocks, the comparative assessment is somewhat restricted by published data on AD system inventories and yields. Co-digestion allows optimisations of biogas yields for energy giving typically 10% uplift in yields, whereas the yields for some of these single feedstocks are likely to be derived from empirical data rather than directly measured from AD plants digesting single feedstocks.

Table 1: Feedstock data taken from a) Poeschl (2010, 2012) and b) Banks and Zhang 2010 and from a food waste AD plant in the UK

Single Feedstocks DM content of original

feedstock (w/w)

Required influent

dm (w/w)

1 tonne of feedstock

provides

Food residue a 16% 12% 1.3 tonnes of influent

Municipal Solid Waste (MSW) a 40% 12% 3.3 tonnes of influent

food waste (source segregated) b 25% 17.5% 1.4 tonnes of influent

Table 2: Dry Matter yields of digestates from AD of waste feedstocks

Single Feedstocks % DM digestate /

tonne original feedstock % DM loss

Processed

influent DM kg/t

Actual kg DM yield /

tonne influent

Food residue 4.0% 75% 120 30

MSW 31.8% 21% 120 95

Food waste (source segregated) 7% 73% 175 48

4.0 Energy substitution credits GHG credits for the substitution of electricity generation used for the assessment (Table 3) are based on the grid average substitution for UK generated electricity based on the latest figures provided by DEFRA (2011). Since any electricity exported to the grid is assumed to substitute emissions from the average generation mix, distribution losses are not factored into the credit, since for simplicity all surplus electricity is assumed to be exported to the grid rather than used directly on site. Conversely electricity used by plant or operations included in this assessment is assumed to be taken from the grid using DEFRA 5 year rolling average, including grid losses, rather than from on-site CHP generation. As all three scenarios will be treated this way with regards to electricity - this will be consistent for the purposes of a comparative assessment. This is at a slight inconsistency with heat generated by pyrolysis gas combustion which is assumed to supplement directly the drying demands estimated specifically for each feedstock. Surplus heat generated on site (minus CHP parasitic demand) is assumed to be exported by the AD plant for another industrial use. GHG emissions associated with average provision of industrial heat are used to estimate the GHG credit (since the exact substitution is unknown). Heat required by the systems for feedstock drying is assumed to come from natural gas furnace (emission factor (d) below), rather than from an average mix of heat



sources since it is considered unlikely that fuels other than gas would be used to provide the belt dryer’s heating duty.

Table 3: Substitution credits for electricity generated and exported to the grid and heat exported for industrial or commercial use in close proximity to source (distribution losses are not factored into heat transfer)

Substitution Unit Average Marginal

Generated electricity kg CO2eq MJ el -1 0.1530 (a) 0.0963 (b)

Industrial heat kg CO2eq MJ th -1 0.0908 (c) 0.0733 (d)

a) GHG EF (scope 3) from average mix at generation / b) Marginal source assumed to be CCGT - (DEFRA 2009) /

c) Average heat supplied assumes GHG (scope 3 –including production emissions etc) from a weighted average

mix of natural gas, heating oil, solid or electricity sources for industrial or domestic use respectively (DECC 2009)

/ d) Assumed typical gas furnace with 85% heating efficiency fuelled by natural gas (scope 3) - based on LHV.

5.0 AD plant assumptions Feedstock pre-treatment and sterilisation For food waste a sterilisation process step is assumed for which energy is required. Also pre-treatment - mixing and processing the feedstock - requires energy. The estimates taken from Poeschl et al. are around 85 MJ electricity and 80 MJ heat per tonne of food waste sterilised (2010). The direct pyrolysis of food waste after drying is assumed not to require this pre-sterilisation energy, although this may need qualification with regulatory bodies. AD CHP system energy efficiency assumptions System demand is percent of the total electricity or heat energy generated assumptions again these estimates are taken from Poeschl et al. (2010, 2012). Data presented here is based on CHP efficiency assumptions given in Table 4.

Table 4: AD CHP system energy efficiency assumptions

Small CHP CHP efficiency System demand

Electrical 33% 2.0%

Thermal 50% 1.8%

Table 5: Biogas yields

Feedstock

m3 per tonne

of original

feedstock

Assumed

biogas CH4

content

MJ per tonne

original

feedstock

Total

electricity

generated MJ

Total

captured heat

energy MJ

Food residue 94.7 60% 2038 673 1019

MSW 123 60% 2649 874 1325

Food waste (source segregated) 120 60% 2592 855 1296



AD fugitive emissions Methane, nitrous oxide and ammonia, an indirect precursor to N2O via atmospheric deposition of nitrogen species to soils, may all be released from AD facilities. Prevention of fugitive residual emissions via improved capture or covered digestate storage has been shown to have a significant influence on the GHG performance of AD plants. Methane emissions from CHP slippage and fugitive emissions have been included based on 10% of methane produced. The few studies presenting nitrous oxide and ammonia emission estimates from stored digestate vary significantly1, so due to this uncertainty this source of GHG emissions has been excluded from the assessment. Further detailed assessments should look to include this when empirical data is available. 6.0 Fertiliser substitution credits The AD digestate fertiliser values were taken to be equivalent to the macro nutrient values reported as nitrogen, phosphorus pentoxide and potassium oxide equivalents in the studies. GHG credits are given, assuming substitution of the manufacturing GHG emissions associated with the equivalent nutrient value of mineral fertiliser. In principle transport emissions associated with the substituted mineral fertiliser should also be credited, however the transport contribution per kg of mineral fertiliser equivalent is assumed to be negligible compared to their manufacturing emissions and has not been included in this streamlined assessment. Digestate is assumed to be spread on land substituting synthetic nitrogenous fertiliser based on equivalent nitrogen content – the plant uptake efficiency are assumed to be the same per kg of total nitrogen. Where solids are separated for pyrolysis, the liquid fraction is assumed to be spread on cropland as in the AD only scenario, however a nutrient loss of 10% nitrogen, 30% potassium and 70% phosphorous is assumed, which is held in the solid fraction to be pyrolysed, based on assumptions made by Poeschl et al. (2012). The fertiliser credits are reduced by the equivalent amount and in proportion to the ratio of moisture off take from the screw-press to the total moisture in available in the digestate before dewatering. This method is fairly crude and more detailed study should measure the digestate nutrient content of separated fractions. Also more detailed assessment should quantify the emission differences for transport and application of digestate and mineral equivalents. GHG emissions for the production of fertiliser were taken from the Biograce standard data.13 Data on the primary energy required for fertiliser production was given for the German context in Poeschl (2010) however the data source (energy mix) and methodology was not substantiated and may not be appropriate for application in this study. o ‘energy credits’ for fertiliser substitution were not included in the energy assessment of the technologies. 7.0 Transport and spreading of digestate Attribution of the emissions associated with loading, transport and spreading of digestate to AD or agriculture depends on whether the digestate is considered a waste product of AD with no value, or as a product with fertiliser value for agricultural use. If considering digestate as a waste with no agricultural value arguably the transport and field emissions could be attributed entirely to the AD plant.

13 www.biograce.net



Digestate management For the assessment of AD only, whole digestate (fibre and liquor) is assumed to be spread locally on agricultural fields without dewatering. From the perspective of abatement per tonne of feedstock processed for each scenario, substituting synthetic fertiliser is assumed. Therefore additional handling and transport emissions of whole or liquid digestate are considered a penalty to this substitution and should also be accounted within the AD plant’s assessment boundary. For the AD only scenario GHG emissions associated with loading, transport and spreading of the raw digestate has been derived from energy data and assumptions given by Poeschl (2010). The distance from plant to field is assumed to be 5 km. Nitrogenous emissions from field spreading The tier 1 IPCC method estimates direct and indirect nitrous oxide emissions as a function of the total nitrogen applied to soils. Following a streamlined assessment approach since the net impact on field nitrous oxide emissions by substituting the equivalent nitrogen in digestate to the cropped field calculated using IPCC tier 1 approach will be zero, the absolute GHG impact from nitrous oxide emissions from spreading digestate for agricultural benefit will not be included in the assessment emissions inventory. Studies have shown that whilst nitrogen uptake efficiency may be demonstrated for manure AD digestate compared to manure in the first year, over 4 years the N mineralisation is not significantly different (IEA, 2010). However marginal differences between nutrient and emission profile of synthetic fertilisers and different digestates should be given greater attention in more detailed studies to better understand the relative impacts and equivalence assumed by using a nitrogen fertiliser substitution approach. 8.0 Preparing the feedstock for pyrolysis Data on digestates was obtained from a UK food waste AD plant to support this part of the analysis. At this site, source-segregated municipal solid waste and commercial and industrial food wastes are digested at 5-6% Dry Solids (DS). The fibrous fraction of the digestate is screened via a screw-press. The current yield from screenings and dewatering per tonne of food waste input is approximately 14.5 kg out of the potential 70 kg of dry matter per day14. For the purposes of this assessment, more efficient solids removal is assumed (60 kg of DM per tonne of feedstock digested), using data provided by Klein GmbH as explained below. The moisture content and calorific value of the screened solids is assumed to be the same as the existing plant (only a greater solids capture rate is assumed). This data is taken from a laboratory analysis of a single sample of the post-digestion screening material at the AD plant. More thorough sampling and tests of the calorific profile of the screened solids resulting from a higher capture rate would need to be conducted for a robust assessment. Dewatering Drying energy requirements were provided by Klein GmbH. For relatively wet feedstocks (>75% moisture) dewatering using screw-press technology was applied to remove moisture to 75% for food residue and MSW digestate, but approximately 60% for source segregated food waste (following the moisture content of the actual sample taken). The electricity demand for this was estimated on the basis of 3.8 kJ per kg of water removed and 10% dry

14 Three tonnes at approximately 40% DM from around 80 tonnes food waste daily input, equating to capture rate of 1.2

tonnes of the 5.5 tonnes of DM solids per day.



matter losses were assumed for screw-press dewatering. These were taken into account in estimating the yield from the original feedstock. The liquid digestate fraction from dewatering was assumed to be landspread and nutrient credits assigned as detailed in the section on digestate management, though a proportion of this liquid fraction may actually be added back to digester for dilution of feedstock to the required influent dm content ‘washwater’ mentioned in Ban s et al. 010 . However, no data were available on the fate of this effluent i.e. the proportion that may be land spread its nutrient content, or the proportion re-circulated. However, based on the assumptions in this assessment, which are based on Poeschl et al. (2012), the net GHG and energy credit is small be compared to the other components. Drying A belt dryer was proposed for drying down from 70% to 30% moisture (required for the pyrolsyis) assuming an average heat demand of 3 MJ per kg of moisture removed. This heat demand was assumed to be provided by natural gas but supplemented with heat recovered from combustion exhaust when burning the syngas from pyrolysing feedstock. The degree of exhaust heat per tonne of original feedstock was calculated from pyrolysis plant assumptions using data on calorific value, moisture and ash content of each feedstock. These are outlined below. 9.0 Pyrolysis plant assumptions No primary empirical data on the performance of the PYEG pyrolysis unit was available and data for the performance of various feedstocks were based on estimates from first principles using a spreadsheet model devised by PYREG engineers. Until detailed measurements can be made to validate and calibrate the model this is considered to be a reasonable approximation of performance by the operational experience of the engineers from PYREG GmbH15. The model’s assumptions are outlined below: Start up heating Start up heat requirements were assumed to be on a weekly basis supplied by natural gas (approximately 9000 MJ per year). These were averaged over the annual running hours (7,500 running hours per year) and estimated annual feedstock input rate for the 500kW pyrolysis plant to attribute of GHG emissions from natural gas combustion to the each tonne of feedstock input. The impact averages around 8-10 MJ of natural gas per tonne of feedstock throughput. Parasitic heat demand from feedstock pyrolysis and moisture Parasitic heat demands of the pyrolysis process were estimated from a generic specific heat capacity (1 kJ/kg K°) which was applied to the dry matter of all feedstock. Fixed specific heat capacity was assumed for ash and chars combined (0.8 kJ/kg K°) for pyrolysis of all sources of biomass. The moisture content of the feedstocks were used to estimate the parasitic heat demand for raising the moisture from ambient (20°C) to boiling point, and the latent heat required for water vapour. These were considered losses since no condensing heat recovery system is employed in the combustion exhaust.

15 Helmut Gerber, Pyreg Head Engineer, personal communication 31/05/2012



Beyond 100°C the heat demand for raising the feedstock and moisture (steam) to 750°C, the pyrolysis temperature provided by PYREG, is assumed to be recovered from the combustion exhaust. It is important to note that the PYREG calculations assume a fixed specific heat capacity of steam, (1.87 KJ/kg K°), presumably assuming an average for the range in conditions in the reactor and combustion chamber. Energy yield Heat losses equivalent to 5% of the calorific yield of the pyrolysis syngas was assumed in the PYREG model of their 500kW pyrolysis plant. For this assessment a further 90% heat recovery efficiency was applied to estimate a net yield from PYREG combustion gases. The assumptions for heat recovery and utilisation would require more detailed calculations in a non-streamlined carbon assessment approach. Pyrolysed carbon yield The total carbon produced in char is assumed by PYREG model to be approximately 60% conversion of the carbon content of the initial feedstock. The system boundary ends with the formation of biochar. The fate of biochar is assumed to be field spreading on local fields and the mass yield per original tonne of feedstock would make the impact of transport to local fields negligible for the purposes of the comparative assessment. These impacts will be included in the final figures of the report for completeness. A conservative storage factor of 20% carbon losses over 100 years is assumed for the purposes of this assessment, following the assumptions of others (Ibarrola et al. 2011, Hammond et al. 2011) based on char being spread on soils. Model Caveats The energy and biochar yields modelled for pyrolysis are dependent on having data on the fuels net calorific value, ash, moisture and carbon content. Laboratory tests for the post digestion-screenings from a UK food waste AD plant were arranged to enable that. Unfortunately, laboratory test data was not available for the same feedstock sources to estimate the energy and GHG abatement from pyrolysis of food waste to compare with the food waste used for AD and AD and pyrolysis of digestate from this waste. That would have contributed to a more accurate comparison of the three technology scenarios. Data on the calorific value, ash, moisture and carbon content of waste sources was found for digestate from pig manure and maize. Banks & Zhang (2010) report calorific values and other data for Municipal Solid Waste segregated at source and post-collection. However, those were laboratory scale experiments where starch bags had been stripped from the food waste before analysis. The post-digestion screening sample sent to the laboratory included starch bags, altering the calorific profile. If we assume the same calorific value for source segregated food waste given by Banks and Zhang then the results should be taken with caution since this may not be representative of the same feedstock used to derive the post digestion screenings.



Appendix B - Business case for the

demonstration phase

Phase 1 of the DIAD project ‘The case for the PYREG slow pyrolysis system in improving the efficiency and profitability of AD plants in the UK’ confirmed the feasibility of using food waste digestate as feedstock for biochar production using the PYREG technology. Phase 1 also highlighted that targets for phasing-out peat use in horticulture have led to a search for new materials not widely adopted in growing media formulation. The few scientific studies looking at properties of biochar produced from digestates suggest that AD prior to pyrolysis has effects that can be expected to be advantageous in horticultural products (e.g. higher surface area and increased cation and anion ion-exchange capacities). Nevertheless, the hypothesis that AD prior to pyrolysis has effects beneficial for use in horticultural products has not been tested directly. Also, AD prior to pyrolysis did not have all of the same effects on the feedstocks tested in the academic studies, and no studies were found on the properties of biochar from food waste digestates. A Biochar Risk Assessment Framework (BRAF)16 is being developed by the UK Biochar Research Centre with support from WRAP and other stakeholders. The BRAF Steering Group will advise on a suitable definition for biochar, which might make reference to the types of feedstocks that can and cannot be used for biochar production, and to suggest a suitable approach for regulating the production and deployment of biochar, which might work as a prelude for a Quality Protocol and / or PAS for biochar. The financial case for integrating PYREG to AD sites rests on operators being able to sell the biochar from post-digestion screenings for horticultural applications. For food wastes digestates not to be overlooked as a potential feedstock for biochar production, the safety and suitability of that type of biochar needs to be demonstrated. That is the aim of phase 2 of this DIAD project. 1.0 Objectives and methodology Work Package 1: Biochar production Upon confirmation that the project has been selected to phase 2 of the DIAD programme, a period of preparatory work will follow to produce bespoke biochar for the experimental work. The phase of implementation will encompass sourcing post-digestion screenings from a food waste AD plant in the UK; transporting the feedstock to PYREG GmbH in Germany, who will produce one tonne of biochar for the experiments; and having the biochar transported from Germany to the UK. Work Package 2: To demonstrate the suitability and safety of biochar from food waste digestate as a component within growing media UK-leading experts on biochar, soils sciences and plant biology have been invited to join the consortium to support phase 2 of this DIAD project. The experts from the University of East Anglia (UEA) and John Innes Centre (JIC) will be responsible for the assessment of the safety and suitability of biochar in horticultural applications.

16 Launched in January 2012, BRAF is funded by the Esmee Fairbairn Foundation (75%) with a contribution from the UK

Biochar Research Centre (25%) and supported by the Environment Agency, the Scottish Environment Protection Agency,

WRAP, the National Farmers Union, Newcastle University, Rothamsted Research and the Biochar Foundation.



In order to appraise the suitability of biochar produced from post-digestion screenings within growing media, pot trials will be undertaken at JIC. The pot trials will be used to establish the influence of biochar upon growing medium performance, including water retention, seed germination success, subsequent plant growth and yield. The replicated design will allow the statistical significance of changes to be evaluated. Towards this end, biochar will be added to a reference growing media with amendment levels of 0% (no biochar control), 1%, 10%, 20% and 50% biochar. The precise growing media will be determined once chemical analysis of the biochar has been obtained, allowing a suitable match to be selected. Three crop plant species are proposed for this screening work, namely, radish, turnip and pak choi. These were chosen on account of their rapid germination, growth and ease of handling. Control and biochar-amended growing media will be placed in 1 L pots and sown with test plant seeds. Seed germination success will be scored in the pots over time intervals of up to 14 days. Thereafter, pots will be thinned to leave one established plant per pot and the plant growth trial continued until point of harvest. Growth will be assessed mainly under glasshouse conditions but some work will employ controlled environment chambers. Destructive assessments to determine biomass at selected time points will be performed and the yield of the normally harvested plant parts will be assessed (wet and dry weights and crop quality). Throughout the study, scientists from JIC who have many years’ experience in underta ing plant growth evaluations will perform blind-test growth assessments, as well as the destructive assessment of biomass, to record and compare key growth parameters. To assess water retention properties, medium moisture levels in both the presence and absence of plants will be assessed and watering requirements will be monitored. In order to appraise chemical hazard associated with biochar, levels of key potentially toxic elements (PTEs) will be evaluated by a research group at UEA that has expertise in this area. Levels of metal and metalloid compounds and polycyclic aromatic hydrocarbons (PAHs) will be assessed in the biochar and the amended growing media (choice of PTE is justified in Freddo et al., In Press). Replicated analysis (n = 10) will allow the statistical significance of changes in levels of PTEs to be established. In addition, PTE levels in the foliage or edible part of plants grown in the control treatments (n = 5) and one of the biochar treatments (to be informed by the plant growth trials) (n = 5) will be assessed for each plant type to evaluate PTE transfer from media to produce. While PTE levels are not expected to be an issue - see Freddo et al. (In Press) wherein PTE levels are reported for a range of biochars - this aspect must be addressed specifically for biochar produced from food waste digestates. There will be significant barriers to market should this information be lacking. A scientist from Rothamsted Research, who sits on the Steering Group of the Biochar Risk Assessment Framework, has been invited to join the consortium on an advisory capacity to ensure the main outcomes of this study are brought to the attention of the Steering Group. Work Package 3: To assess the carbon benefits of incorporating biochar from food waste digestate to growing media formulations Following the pot trials on the impact of biochar produced from food waste digestate on plant growth and crop yields, an approach will be developed in conjunction with the experimental team to assess the potential carbon benefits of incorporating biochar to growing media formulations. A desk-based evaluation comparing the GHG emissions



associated with the production and use of growing media using biochar amendments shall be conducted using a lifecycle approach. This will be subject to available data on typical commercial formulations and building on published reports. The evaluation will also take into account the results obtained from experiments to formulate growing media and resulting increases in crop yields. Work Package 4: To estimate the costs at which biochar from food waste digestate would have to be supplied for horticultural applications Following the analysis of the results from pot trials, the biochar-enriched growing media formulations will be ranked according to their perceived utility. The InCrops Business Innovation Managers will then carry out an industry consultation to estimate at which costs biochar would need to be supplied to enable industry uptake. The consultation will also aim to identify other potential barriers to market. A tiered approach beginning with key experts and main players, and then feedstock suppliers, growing media manufacturers, professional growers and retailers of horticultural products, will be applied to consult with industry. The intention is to consult with at least 50 UK stakeholders. The biochar-enriched growing media formulations will then be ranked according to the economic feasibility of using biochar from food waste digestates in different segments of the market. Work Package 5: Project Management and Reporting Face-to-face meetings involving all members of the consortium will be hosted in Norwich and the dates for those meetings will coincide with the completion of major project milestones. That will be particularly important to enable the findings from Work Package 2 (assessment of the suitability and safety of biochar in growing media) to be communicated to the wider group, enabling individuals involved in Work Package 3 (carbon assessment) and Work Package 4 (cost modelling) to make informed decisions on how to proceed with their work. Consortium partners will maintain accurate and informative notes of the experiments and industry consultation, in order to be able to provide concise but informative updates to funders via phone conferences and face-to-face meetings if required. The project manager will be available to answer any questions the client might have via phone or email. Work Package 6: Dissemination The consortium expects the key audiences for the results of this study to be:

Operators of food waste AD plants in the UK, for whom the results will demonstrate the

safety and value of biochar from digestates in growing media, with the view to enable

them to develop higher value uses for digestates.

Manufacturers of growing media and soil amendments, for whom biochar might provide

an opportunity for product development, including in innovative growing media

formulations that could displace peat-based growing media.

Professional growers, for whom biochar might constitute a cost effective and

environmental sound alternative to improve soil structure and quality, support plant

growth, increase crops yields and sequester carbon in soils.

The Steering Group of the Biochar Risk Assessment Framework, who over the next two

years will be assessing the risks associated with the production and deployment of

biochar, with the view to support a Quality Protocol and / or PAS for biochar.

Government departments, policy developers and regulators, who might be interested in

the potential and barriers for innovation in the AD and horticultural sector or in meeting

GHG reduction commitments (e.g. WRAP, Defra and the EA).



The contractors will use more than one approach and a variety of channels to promote the project and communicate the outputs of the study to the audiences above:

The project will be promoted on the website and newsletter of the InCrops Enterprise

Hub as soon as it starts, with the view to enable any interested parties to contact the

contractors should they wish to respond to the consultation.

The consortium will seek to disseminate the results through relevant sector-specific

publications and through business support networks, with the view to identify companies

that might have an interest in getting involved with future projects.

If authorised by funders, consortium members will disseminate the findings from the

study at scientific conferences and industry-focused events for which the topic of the

project will be relevant.

InCrops proposes to run an event at the close of the project to disseminate the main

conclusions from the research and enable companies with an interest in this field to

network with potential partners for collaborative projects.

The networking event could be hosted at the University of East Anglia, John Innes Centre or Rothamsted Research, and would aim to attract at least 50 organisations.


2.0 Project timescale

Work Packages and milestones Working weeks

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 48 50

WP 1: Project implementation

A) Source sample of post-digestion screenings from food waste for PYREG

B) Production of biochar using post-digestion screenings by PYREG

C) Biochar from post-digestion screenings delivered at JIC

WP 2: Glasshouse trials and safety tests

D) Analysis of the biochar for nutrient content

E) Set up and run glasshouse trials at the John Innes Centre

F) Safety analysis of biochar, growing media and crop samples

G) Analysis of data on biochar impact on media and growth rates

WP 3: Carbon benefit analysis

H) Assessment of the carbon benefits of biochar in growing media

WP 4: Cost estimation

I) Analysis of results from pot trials (cost implications of formulations)

J) Consultation with the horticultural and AD sectors and regulators

WP 5: Project management and reporting

K) Meetings of the Steering Group ● ● ● ●

L) Report to WRAP * * * * *

M) Production of Demonstration Report to WRAP (and delivery deadline) *

WP 6: Dissemination

O) Attendance at relevant conferences and meetings



3.0 Breakdown of costs

Work Package 1: Biochar production

Bianca Forte (2 days @ £500/day) 1,000.00

Mike Weaver (4 days @ £350/day) 1,400.00

Transport of post-digestion screenings from the UK to Germany 1,257.00

Production of 1 tonne of biochar by PYREG GmbH (cost: EUR 400 - 1.2 EUR = 1 GBP) 333.00

Transport of biochar produced from Germany to the UK 419.00

Travel expenses 500.00

TOTAL 4,909.00

Work Package 2: Glasshouse trials and safety tests

Dr Brian Reid (8 days @ £396.20) 3,169.60

Glasshouse trial, JIC (four months) 47,680.00

Analysis of 90 samples for metals/metalloids 1,916.10

Analysis of 90 samples for PAHs (16 US EPA compounds) 1,592.10

TOTAL 54,357.80

Work Package 3: Carbon benefit estimations

Peter MetCalfe (20 days @ £500/day) 10,000.00

TOTAL 10,000.00

Work Package 4: Cost estimation models

Dr Mark Coleman (8 days @ £500/day) 4,000.00


Michael Weaver (2 days @ 350/day) 700.00

Travel expenses 1,000.00

TOTAL 9,700.00

Work Package 5: Project management and reporting


Michael Weaver (2 days @ £350/day) 700.00

Dr Brian Reid (2 days @ £396.20/day) 792.40

Prof Keith Goulding (4 days @ £500/day) 2,000.00

Dr Mark Coleman (2 days @ £500/day) 1,000.00

Travel expenses 2,000.00

TOTAL 10,492.40

Work Package 6: Dissemination

Attendance at relevant conferences 1,000.00

TOTAL 1,000.00

TOTAL COST (exc VAT) 90,458.80

TOTAL COST (inc VAT @ 20% for eligible items) 107,754.96



4.0 Key personnel 4.1 Dr Brian Reid, University of East Anglia (UEA) Dr Brian Reid will lead on the biochar safety assessment and data analysis and interpretation and will work closely with the team involved with the glasshouse trials. Brian graduated from Edinburgh University with a First Class BSc (Hons) degree in Environmental Chemistry in 1996 and from Lancaster University with a PhD in 2000. He became a Lecturer in the School of Environmental Sciences of the UEA in that same year. A Fellow within the Higher Education Academy since 2007, Brian convenes a semester long unit entitled ‘ oil Environments and Processes’, contributes to a unit entitled ‘Pollution and Toxicology’ and teaches on the irst Year Undergraduate Field Course. Brian was the recipient of the Sir Geoffrey and Lady Allen Prize for Excellence in Teaching in 2009. Professionally, Brian has held the position of President (2007-08) and of Director (2004-2008) of the UK branch of the Society for Environmental Toxicology and Chemistry (SETAC-UK). He has acted as a technical advisor to the Environment Agency and as a consultant to a number of companies. Brian’s research interests include environmental chemistry and soil science. He is currently supervising two PhD projects on the influence of biochar upon soil properties (nutrient balances and water storage and release) and the hazard associated with biochar components with respect to soil health. His recent research with international collaborators (Khan et al., In Press) on the effects of sewage sludge (SS) and biochar produced from the same sewage sludge (SSBC) indicated the greater potential SSBC has over SS with respect to promoting plant growth and reducing individual PAH bioaccumulation. 4.2 Dr Ian Bedford and Barry Robertson, John Innes Centre Dr Ian Bedford and Barry Robertson will be the lead staff for the assessment of impact of biochar on plant growth and growing media properties. Scientists from JIC have many years of experience in undertaking plant growth evaluations. The glasshouses facilities at JIC are of high quality with computer-controlled environments, allowing for the precise control of the plant environment. The team of staff who works at the facility provides a range of services to companies in the horticultural sector. They regularly engage with local professional growers. The team have in excess of 25 years of experience with product evaluation and trailing and JIC is officially accredited by Defra CRD as a testing organising (ORETO247). 4.3 Prof Keith Goulding, Rothamsted Research Prof Keith Goulding sits on the Steering Group of the Biochar Research Assessment Framework and has been invited to join the project on an advisory capacity. Keith joined Rothamsted Research in 1974 after completing an MSc in Soil Chemistry at Reading University and gained his PhD in Cation Exchange at Imperial College in 1980. He is currently Science Director for the Centre for Soils and Ecosystem Function at Rothamsted Research, where his research focuses on nutrient cycling, especially losses of nitrogen to air and water and their environmental impact, with a strong emphasis on policy-relevant research. Keith’s research interests also include nutrient losses from agriculture. Keith is Vice-President of the British Society of Soil Science. He is a visiting Professor at the University of Nottingham, a Fellow of the Institute of Professional Soil Scientists and Honorary Fellow of the Royal Agricultural Society of England. Keith was awarded the Royal Agricultural ociety of England’s Research Medal in 003 for his research into diffuse



pollution from agriculture and a Nobel Peace Prize certificate for his contribution to the work of the Intergovernmental Panel on Climate Change, for which the Panel and Al Gore were jointly awarded the Prize in 2007. Keith’s studies on soil structure, quality and degradation supported the development of the Soils Strategy for England, the revision of the Fertiliser Recommendations for Agricultural and Horticultural Crops, and the development of a national set of indicators of physical, chemical and biological soil quality. Keith has contributed to a number of studies on the potential of biochar in improving soil structure and quality. He sits on the Steering Group of the Biochar Risk Assessment Framework and will join the consortium to ensure the main outcomes from the demonstration project are communicated to the group. 4.5 Bianca Forte, Pete MetCalfe and Dr Mark Coleman, NeueAg Ltd Dr Mark Coleman will be the project manager for Phase 2 and will work with Bianca Forte on the industry consultation process; Pete MetCalfe will carry out the carbon assessment. The InCrops Enterprise Hub is a £3.8M project funded by the East of England Development Agency and European Regional Development Fund with match funding from 13 partners, including the University of East Anglia, John Innes Centre and Rothamsted Research. InCrops has access to a network of over 140 stakeholders in the bioenergy and biofuels sectors and over 100 stakeholders in the horticultural and agricultural sectors. Bianca Forte is the lead Business Innovation Manager for activities in those sectors and has worked with a range of companies involved with or interested in biochar and AD, including: technology developers and suppliers; growing media manufacturers; retailers of horticultural products; agricultural consultants; farmers; and land owners. Bianca co-authored the 2010 InCrops report on the barriers for the commercialisation of biochar and towards the end of last year she set up the InCrops Soil Improvement Working Group to accelerate progress with the implementation of the recommendations of the report. Bianca is jointly based at the UEA and Rothamsted Research. Mark is jointly based at the UEA and at the JIC. Seconded from the UEA, Mark retains a 0.2 FTE role as a member of faculty within the School of Biological Sciences where he is a lecturer in plant biology for both undergraduate and post-graduate degree courses. With a BSc in Biochemistry and a PhD from Imperial College, Mark has over twenty years of research experience in the areas of plant-pathogen interactions. Mark plays a key role in supporting InCrops clients in a range of sectors, including bioenergy and biofuels, and is a member of the British Bio-Alcohols Group. As Technical Projects Officer, Peter MetCalfe uses lifecycle analyses and carbon footprint concepts in assessing the greenhouse gas impacts of food and farming. He has practical experience in estimating carbon footprints for food and drink produce and a specific interest in sustainable low carbon food production. Before joining LCIC, Peter worked for CRed conducting practical surveys that aimed to help business and organisations understand and reduce their greenhouse gas emissions. He has also implemented practical scientific approaches to evaluate actual exhaust emissions alongside his work on greenhouse gas assessment of biodiesel using concepts given in ISO14040 series for lifecycle analyses. 4.6 Mike Weaver Mike Weaver, a Cambridgeshire-based entrepreneur, is a shareholder in PYREG GmbH and has the exclusive license to market the system in the UK and Ireland, where he is in the early stages of introducing the technology. Mike will act as the point of contact for PYREG GmbH, who will manufacture be-spoke biochar from post-digestion screenings for the trials, and will support the work on the cost sensitive analysis.



5.0 Project Financing The consortium is seeking funding from WRAP in the total value of £107,754.96 (inc VAT) to enable the work described in this Business Plan to progress. The Work Packages suggested herein can be adapted to suit particular requirements by WRAP. 6.0 Commercialisation of the technology post demonstration Our market research has shown that AD operators recognise that the industry might come under increasing pressure in the future. Looking at feedstock supply, as more plants are built in the UK, operators might become under increasing pressure to compete on gate feeds for taking in waste. Looking at the medium to long term use for digestates, there could be increasing competition for access to land on which to spread the product. The demand for new materials for soil improvers and growing media formulations makes PYREG an attractive option for AD plants looking to upgrade digestates. Estimating the size of the market for biochar produced from post-digestion screenings is a difficult task, given the limited number of studies looking at that feedstock and even fewer publications available on the use of biochar in the professional growers sector. Nevertheless, we believe demand for biochar in the professional growers sector should increase considerably from 2014 if the work that is being carried out by the Steering Group of the Biochar Risk Assessment Framework enables the development of a Quality Protocol and / or PAS for biochar by then. Provided that is achieved, our forecast for the number of AD plants incorporating the PYREG system in the UK should be 10 plants within 5 years from the completion of the demonstration project. In addition to addressing the opportunity in the AD sector, Mike Weaver is planning to approach operators of other types of waste management facilities, such as composting sites, land managers and partnerships of farmers. As the UK mar et develops, it is Mi e Weaver’s intention to eventually engage a UK entity capable of making, under licence, the equipment and develop a servicing to serve the UK.

www.wrap.org.uk/diad

Documents

Feasibility Report The case for the PYREG slow pyrolysis ... I NeueAg feasibility report.pdf · The case for the PYREG slow pyrolysis process in improving the efficiency and profitability