Renewable Heat in Coastal Communities - District Heating Case Study

RENEWABLE HEAT IN COASTAL COMMUNITIES:

DISTRICT HEATING CASE STUDY

by

Linda C Forbes

August 2009

A dissertation submitted in the partial fulfilment of the requirements for the

degree of

Master of Science

in Renewable Energy Development

Institute of Petroleum Engineering

Heriot-Watt University

Orkney

CONTENTS

Linda Forbes Page i

INTRODUCTION ................................................................................................ 1

AIMS .................................................................................................................. 3

CRITICAL REVIEW OF LITERATURE ......................................................... 4

1. DRIVERS FOR RENEWABLE HEAT ........................................................ 4

1.1. EU Directive 2009/28 on promotion of energy .................................... 4

from renewable sources ................................................................................... 4

1.2. EU Directive 2006/32 on energy-end use and energy services ................ 5

1.3. Climate Change (Scotland) Bill .................................................................... 5

1.4. Scottish Government policy – Renewable Action Plan ............................ 6

1.5. Costs of national policies and administrative barriers ............................. 8

2. HEATING DEMAND .................................................................................... 9

2.1. Heat demand in the UK .................................................................................. 9

3. DISTRICT HEATING SCHEMES ............................................................. 10

3.1. Perceptions and penetration of district heating ....................................... 10

3.2. Development of district heating in the UK ................................................ 12

3.3. Heat density and financial viability ............................................................ 13

4. HOUSING CONDITIONS .......................................................................... 14

4.1. Stock survey of Scottish homes ................................................................ 14

4.2. Energy efficiency of existing buildings ..................................................... 15

4.3. Building standards in Scotland .................................................................. 15

4.4. Wind chill factor in exposed locations ...................................................... 16

4.5. Fuel poverty .................................................................................................. 16

4.6. Insulation grants and energy efficiency improvement schemes ........... 17

5. PLANNING STROMNESS ........................................................................ 18

5.1. Orkney Local Plan..................................................................................... 18

6. ENERGY SURVEY .................................................................................... 20

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6.2. Survey area ................................................................................................... 21

6.3. Questionnaire design .................................................................................. 22

6.4. Response rates ............................................................................................. 23

6.5. Property sizes and heating regime ............................................................ 23

6.6. Fuels and technologies ............................................................................... 23

6.7. Heat loss from buildings ............................................................................. 24

6.7.1. Insulation .................................................................................................... 25

6.7.2. Loft insulation ............................................................................................ 25

6.7.3. Double glazing and draught proofing ..................................................... 26

7. POTENTIAL ENERGY SOURCES .......................................................... 27

7.3. Heat sources ................................................................................................. 27

7.3.1. Large scale power plants ......................................................................... 27

7.3.2. Small scale power plants ......................................................................... 27

7.4. Biomass ......................................................................................................... 28

7.4.1. Willows and short rotation coppicing .................................................... 28

7.4.2. Other biomass crops ................................................................................ 29

7.5. Heat pumps ................................................................................................... 29

7.5.1. Ground ........................................................................................................ 30

7.5.2. Sea water .................................................................................................... 30

7.6. Anaerobic digestion ..................................................................................... 30

7.6.1. Qualified potential ..................................................................................... 31

7.6.2. Farmyard waste ......................................................................................... 32

7.6.3. Waste water treatment and human sewage .......................................... 33

7.6.4. Seaweed – biomass for anaerobic digestion ........................................ 34

7.7. Energy-from-Waste ...................................................................................... 34

7.7.1. Material excised as provided ‘commercial in confidence’ ........................... 35

7.8. Backup options - wind to heat and solar thermal .................................... 35

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8. MODELLING OF HEAT DEMAND AND SUPPLY .................................. 36

8.1. Maximum local heat demand ...................................................................... 36

8.2. Phased construction and connection ....................................................... 37

9. COSTINGS ................................................................................................. 39

9.1. Infrastructure ................................................................................................ 40

9.1.1. Anticipated lifetime of plant and network .............................................. 40

9.1.2. Pipework ..................................................................................................... 40

9.1.3. Heat exchangers ....................................................................................... 41

9.1.4. Heat meters ................................................................................................ 42

9.2. Financial support mechanisms .................................................................. 42

9.2.1. Renewable Heat Incentive ........................................................................ 42

9.2.2. Enhanced Capital Allowance ................................................................... 43

10. OPERATING STRUCTURES ................................................................. 44

DISCUSSION ................................................................................................. 45

BIBLIOGRAPHY .............................................................................................. 55

Appendix 1 – Scottish Heat Map .............................................................. 56

Appendix 2 – Survey Schedule and Questionnaires ................................ 57

Appendix 3 – Key District Heating Schemes in UK .................................. 60

Appendix 4 – Insulation material .............................................................. 62

Appendix 5 – Wind Chill Factor ................................................................ 63

Plagiarism Statement ....................................................................................... 64

Figure 1: Existing Incentives (FREDS, 2008b) .................................................. 7

Figure 2: From Source to Delivery (MVV Consulting, 2007) .............................. 8

Figure 3: UK Heat Demand, 2009 and 2020 (NERA, 2009 from Department of

Energy & Climate Change, 2009) ....................................................................... 9

Figure 4: Energy Use in Scotland ....................................................................... 9

Figure 5: Breakdown of Scotland’s Space Heating and Hot Water Demand ...... 9

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Figure 6: The Roman Baths, Bath .................................................................... 10

Figure 7: Penetration of District Heating by Building Types ............................. 11

Figure 8: District Heating Market Share (Ecoheatcool, 2006b, page 11) ......... 13

Figure 9: Age & Number of Dwellings (Scottish Government, 2007) ................ 14

Figure 10: Energy Performance Certificate (Directgov, 2008) .......................... 15

Figure 11: Stromness, Orkney (Ordnance Survey, 2009) ................................ 18

Figure 12: Proposals Map 2 - Stromness (Orkney Local Plan, 2005b) ............ 19

Figure 13: Stromness - Surveyed Area ............................................................ 21

Figure 14: Number of rooms in house .............................................................. 23

Figure 15: Number of Rooms Heated in Houses .............................................. 23

Figure 16: Fuels & Technologies in Use .......................................................... 23

Figure 17: Heat Loss & Insulation (DEAC, 2007) ............................................. 24

Figure 18: Thermal Image (Press Association, 2008) ...................................... 24

Figure 19: Home Insulation Levels ................................................................... 25

Figure 20: Distribution Curve of Depths of Loft Insulation ................................ 25

Figure 21: Double Glazing & Draught Proofing ................................................ 26

Figure 22:Sea Surface Temperature Data – 2002 & 2003, (Hughes, 2005) ... 30

Figure 23: Lerwick District Heating (Martin, 2007) ........................................... 34

Figure 24: Heat Demand Profile, North Stromness .......................................... 36

Figure 25: Target Consumers in Stromness..................................................... 36

Figure 26: Overall Monthly Heat Demand and Potential Means of Supply ....... 37

Figure 27: Phase 1 Heat Demand and Supply ................................................. 38

Figure 28: Pipework Burial (Uponor, 2007) ...................................................... 40

Figure 30: Pipeline Costs in Sweden (Nilsson et al, 2007) ............................... 41

Figure 29: Building Density and Connection Costs .......................................... 41

Figure 31: Heat Exchanger (Utilicom, 2008) .................................................... 42

Figure 32: Ownership Models in Sweden (Ecoheatcool, 2006A) ..................... 44

Figure 33: Heat Sources in Sweden (Nilsson et al, 2008) ................................ 48

ACKNOWLEDGEMENTS

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I would like to thank Dr Sandy Kerr for his encouragement during the writing of

this thesis: his patience is reassuring and comments were always helpful.

To the residents of Stromness who took the trouble to complete and return the

survey forms so promptly – I really do appreciate your time and consideration

as without your responses I could have done little. Many of you gave freely of

your time to discuss various aspects of renewable energy during the course of

my work – I gathered much additional knowledge from these conversations.

For their help in explaining how they and their businesses were using, reducing

or producing energy, be it ‘brown’ or ‘green’, while addressing sustainability I’d

like to record my appreciation and mention particularly Russell Anderson,

Highland Park Distillery, Kirkwall; Richard Gauld, Orkney Sustainable Energy

Ltd, Stromness; Kenny Inkster, Orkney Herring Ltd, Stromness; Neville Martin,

Shetland Heat and Power Ltd, Lerwick; Dave Marwick, Scottish Water, Kirkwall;

Alistair Morton, Energy Manager, Orkney Islands Council, Kirkwall; Colin

Risbridger, Heat & Power Ltd, Westray; Ken Ross, Orkney Energy Agency,

Kirkwall; and James Walker, Orkney Meat Ltd, Kirkwall.

INTRODUCTION

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INTRODUCTION

Inspired by a group assignment earlier in this Renewable Energy Development

Masters course and encouraged by the enthusiasm of local councillors, this

thesis explores the potential for district heating schemes in coastal communities

being powered by renewable energy sources.

During the period of research and at the time of writing, the impacts of the

global recession continue to crash down particularly hard on the UK, with rising

unemployment, personal and commercial insolvencies, and homes being

repossessed. With the level of public debt being incurred to support the financial

sector, it is difficult to comprehend how UK plc and its shareholders, the

citizens, will find the funds to deliver energy security in the coming oil crunch.

While it’s possible to feel some regret that the benefits of North Sea oil to the

UK economy have not been ring-fenced as in Norway for future generations, or

targeted more effectively, as in Shetland with its development of district heating

schemes and community centres, we must focus on maximising the remaining

carbon income in meeting renewable energy targets agreed within the EU.

One could regard the effects of the recession positively: falling demand leading

to industrial closures and reduced imports thereby cutting demand for oil and

lowering our CO2 emissions, a government promise that a cohort of the

unemployed is to be trained as installers of insulation and renewable energy

technologies, ‘staycations’ leading to fewer flights and Ryanair grounding some

of its fleet, while people show a greater interest in local food production.

But, demand for fossil fuels will rise again as growth returns to the economy and

this will be reflected in the increasing cost of keeping warm in winter. The UK’s

reliance on imported fuels bought with a weakened currency makes us

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vulnerable – examining how some of these needs might be met from home-

grown resources is an essential first step in taking action. The conflict between

supporting economic growth and minimising environmental impacts remains

unresolved at the heart of our society – might not money targeted towards the

car scrappage scheme have been better employed in a mass insulation project?

Enthusiasm at governmental level for renewable heat is clearly evident in the

many policy documents and legislation being brought forward: some foot

dragging is already apparent though as the Renewable Heat Incentive is

delayed until 2011.

Opportunities abound in the field of renewable heat for the development of new

industrial processes and supply chains to replace those of oil handling and

refining: this thesis investigates some of the potential sources of replacement

fuels and how they might be accessed by coastal or remote communities in

order to become less dependent on fossil fuels for their heating and hot water.

The majority of the research was undertaken in Orkney, with the main focus

being on the community in the northern part of Stromness. However, during the

survey stage of this thesis, the local authority, Orkney Islands Council,

advertised its tender for consultants to undertake a feasibility study into the

potential for a district heating scheme in Stromness.

As this study will require the surveying of commercial organisations approached

during my thesis, my ability to follow-up non-respondents was fettered by my

concern not to overburden or confuse participants. Accordingly, the focus of the

thesis changed to reflect the fact that information relating to the industrial

heating/cooling loads in Stromness was unavailable and could not be factored

into overall demand/supply calculations.

Although precluding the completion of a detailed mass balance of heating

requirements for one particular scheme, i.e. Stromness, the setback to data

gathering described has encouraged in this thesis a wider perspective as to the

opportunities there may be for recovering energy from with a locality.

AIMS

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AIMS

Sustainable energy = energy efficiency + renewable energy

This thesis explores the hypothesis that domestic, industrial, and commercial

buildings in coastal communities could obtain their heating, cooling and hot

water needs through district heating schemes powered by renewable energy.

The example of a remote coastal community in which to test this hypothesis is

Stromness in Orkney: however, the premise is that the processes underpinning

the research are translocatable to and replicable in other geographies.

The research will examine heating energy use within a specific locality and aims

to identify how users might optimise these requirements. It will explore fuels and

technologies that may be available for use within a local district heating

scheme, and aims to establish running costs, and those of installation.

It will examine whether governmental and financial drivers encourage, or

discourage, the potential for such schemes, and consider how the effectiveness

of these drivers could, or should, be improved. Comparisons with outcomes in

other countries will be used to inform opportunities and pitfalls in delivering

renewable heat to consumers.

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CRITICAL REVIEW OF LITERATURE

1. DRIVERS FOR RENEWABLE HEAT

Support for and encouragement of delivery of heat from renewable energy

sources and waste streams powered by fossil fuels are being legislated into

action through a number of key documents arising from Brussels, Westminster,

and Holyrood. Furthermore, the development of a renewable heat industry can

offer economic and employment opportunities at national and local levels, while

reducing dependence on energy imports from unstable regions or from those

countries with poor records in human rights.

1.1. EU Directive 2009/28 on promotion of energy from renewable sources

During the proposal stages of this Directive, it was noted that development of

the renewable heat sector within the EU was almost stagnant, and that

promotion through legislation would encourage economic development, energy

efficiency, and lead to reductions in emissions (Commission of the European

Communities, 2008). With generation of electricity and transport use of biofuels

covered by earlier renewable energy Directives, a decision was made to

address this sector. The Directive, enacted by the European Parliament on 23rd

April 2009, has until 5th December 2010 to be adopted into UK law, Article 4

describing a requirement for national renewable energy action plans to be

prepared by each member state.

Article 17 lays obligations regarding district heating networks upon member

states. This requires national energy action plans to investigate whether district

heating infrastructure will be required to deliver their 2020 targets, and, if

necessary, consider how this might be implemented to provide heating and

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cooling schemes, using biomass, solar, or geothermal sources. Article 5

explains the criteria to use when calculating the energy consumption of heating

and cooling generated from renewables and other sources, while minimum

conversion efficiencies for biomass are given in Article 13.

A nod in the direction of the Merton Rule is also apparent in Article 13, as it

recommends that building development and refurbishment should be taken as

an opportunity to install energy-efficient heating and cooling systems, including

district heating schemes, powered by renewable energy. This is reinforced by

the content of Clause 33 which states that …Planning rules and guidelines

should be adapted to take into consideration cost-effective and environmentally

beneficial renewable heating and cooling and electricity equipment.

To encourage implementation of schemes, specific reference is made in the

Directive to member states addressing and removing gaps in information and

training which might hinder deployment of renewable energy technologies.

1.2. EU Directive 2006/32 on energy-end use and energy services

Promoting access to and use of energy-efficient products and services, this

Directive suggests that installation of district heating and cooling systems be

considered as means of improving energy efficiency.

1.3. Climate Change (Scotland) Bill

With ratification of the Climate Change (Scotland) Bill in July 2009, and

publication of a Renewable Action Plan in the same month, the Scottish

Government leads the way in the UK in promoting the use of renewables.

Setting a 2050 target of reducing carbon dioxide emissions by 80% from 1999

baseline figures, with an interim reduction of 42% by 2020, this Bill mandates

energy efficiency and heat from renewable energy in meeting its aims. Scottish

Ministers have been given a duty to promote both, while for renewable heat

they must produce a Renewable Heat Action Plan by 24th June 2010, including

targets and dates, which will deliver a proportion of Scotland’s heat

requirements from energy sources other than fossil fuels and nuclear power.

The Bill also makes clear that ‘the use of … surplus heat from electricity

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generation or other industrial processes for district heating or other purposes’ is

to be included when considering energy efficiency measures.

1.4. Scottish Government policy – Renewable Action Plan

In this Plan, renewable heat is described as that produced from low carbon

renewable sources. This heat may be derived from biomass and its wastes,

heat source pumps (all media), anaerobic digestion of wastes, solar heating,

wind to heat, or geothermal energy. The Plan identifies the development of

renewable heat as a top priority for Scotland, given the lack of market

penetration (currently 1.4%) and the scale of the demand by 2020 (2.1GW):

it proposes the following interim targets for renewable heat:

• 2% by 2011;

• 6.5% by 2015; and

• 11% by 2020.

It is clear from much of the policy documentation that the Scottish Government

sees biomass meeting the majority of the nation’s more immediate renewable

heat needs, with uptake being promoted through the use of demonstrator

projects. Heat pumps and solar heating are seen as supporting the medium- to

long-term demand.

However, it is noted that fewer than 4,200 hectares of new woodland were

planted in Scotland in 2008: despite the Scottish Government’s 10,000 hectares

annual target designed to increase woodland cover from 17% to 25% by 2050

(Forestry Commission Scotland, 2009). Should biomass demand require to be

met through imported wood-based fuels, as is the case in Orkney, then fluctuations

in cost and availability must surely influence decisions on technology selection.

Furthermore, the Strategic Environmental Assessment of the plan warns us that

combustion of biomass can release feedstock-dependent air pollutants,

including SOx, NOx, and particulates, while other pollutants, such as ammonia

from fertilisers, may be released during cultivation of biomass crops.

While development of a number of new heat installations in Scotland is now

underway, these will satisfy only 4.6% of 2020 demand. Predictably, the lack of

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joined-up thinking is demonstrated starkly by the development at Steven’s Croft

outside Lockerbie, where electricity is generated by combustion of biomass,

with heat being vented to atmosphere. This was truly a missed opportunity that

must not be repeated.

Despite the foregoing, the authors of the plan recognise that the potential for

recovery of existing by-product heat from waste facilities (common in many

Danish towns and cities) is important in meeting the 11% target – this

alternative may minimise costs by reducing reliance on future biomass imports

and the environmental impacts of their international transport.

The government also identifies a potential role for local communities in

developing community or district heating schemes and networks, particularly in

areas where the natural gas grid is absent.

There is a plethora of advice available to individuals, communities, and

companies; while funding may be accessible depending on the criteria at time of

application. Currently, the Communities and Renewable Energy Scheme

(CARES), successor to the Scottish Community and Householders Renewables

Initiative (SCHRI), supports renewable energy projects which promote its goals

of community cohesion, energy security and reducing fuel poverty. This maze of

benefits, incentives, and potential sources of funding available to project

initiators and operators is laid out below, having been identified by the

Renewable Heat Group at Forum for Renewable Energy Development in

Scotland.

FIGURE 1:

EXISTING INCENTIVES

(FREDS, 2008B)

Finally, given the

significant up-front

costs incurred during

consultation and

construction stages of district or community heating schemes, there may be a

need for the government to underwrite funding mechanisms in support of the

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development of renewable heat. Moreover, with scant experience of installing

and operating district heating schemes in the UK, there are supply chain risks

which will require to be addressed so as to ensure the quality of professional

advice and selection and delivery of appropriate capital equipment. Those

wishing to integrate renewable heat into communities must be able to do so,

while having confidence in their advisers and suppliers. Proposed support

mechanisms must, however, not breach EU legislation prohibiting state aid.

1.5. Costs of national policies and administrative barriers

MVV Consulting’s report for the European Commission DGTREN in 2007 examined

the technological development of three renewable heat resources (solar thermal,

geothermal, and biomass) by country, and the capacity and potential for their use in

each. Figure 2 shows the routes from resource to delivery of heating and cooling

which underpinned the research.

FIGURE 2: FROM SOURCE TO DELIVERY (MVV CONSULTING, 2007)

The effect of support schemes, such as grants, obligations, and feed-in tariffs, in

promoting these renewable options formed a significant element of the report and

highlighted the need for improved data gathering on final heat consumption across

all EU member states in order to develop effective policies for promoting renewable

heating and cooling. Furthermore, it was perceived that the long lifecycle of heating

systems would make it difficult to measure how well particular support schemes

have encouraged deployment.

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2. HEATING DEMAND 2.1. Heat demand in the UK

NERA Economics (2009) projects a fall in UK heating demand between 2009

and 2020 (Figure 3, below) but does not suggest how this might be split across

the devolved nations.

This projected fall in UK’s heat demand is

almost exclusively within the domestic

sector, an anticipated outcome of

improved building standards and insulation

programmes.

FIGURE 3: UK HEAT DEMAND, 2009 AND 2020

(NERA, 2009 FROM DEPARTMENT OF ENERGY &

CLIMATE CHANGE, 2009)

The energy required to meet

Scotland’s heating and hot water

demand comprises 57% of the

nation’s overall energy use, and is

double that used by transport

(Figure 4, Forum for Renewable

Energy Development in Scotland -

FREDS, 2008b).

The Forum for Renewable Energy

Development in Scotland (FREDS)

estimates that 6.4TWh will be

required to meet the 11% renewable

heat target for 2020. Meanwhile,

IPA’s report for Scottish Renewables

calculated that a 50/50 split in

demand for heat between domestic

and commercial/industrial sectors

exists (Figure 5).

FIGURE 4: ENERGY USE IN SCOTLAND

FIGURE 5: BREAKDOWN OF SCOTLAND’S SPACE HEATING

AND HOT WATER DEMAND BY SECTOR (IPA, 2008)

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3. DISTRICT HEATING SCHEMES

Article 2 of Directive 2009/28/EC defines district heating or cooling as:

‘…the distribution of thermal energy in the form of steam, hot water or chilled

liquids, from a central source of production through a network to multiple

buildings or sites, for the use of space or process heating or cooling;’

Might we then consider hypocausts such as those in Greece dating from 4th

century BCE and excavated in the late 19th century AD to be the precursor of

district heating? (Winter, 2004). This concept was embraced by the Romans:

whose complex systems, overlaid by mosaic

floors, allowed warm air to circulate thereby

heating the waters in bath houses and the

villas of the wealthy.

FIGURE 6: THE ROMAN BATHS, BATH

Ecoheatcool (2006) tells us that the oldest district heating in the world is a

French geothermal heat system which has been operating since the 14th

century, while an American inventor, Birdsill Holly, is often credited with opening

the first commercially successful district heating system in 1877.

3.1. Perceptions and penetration of district heating

The continuum of public perceptions of district heating systems lies between

tales of inflexible systems in Stalinist blocks of flats in 1950s USSR – hot in

summer and cold in winter, and more positively, that of modern warm homes in

Scandinavia, with pale pine furnishings and cosy underfloor heating.

Denmark provides an example of what can be achieved. By 2000, 97% of

homes in the city were connected to district heating networks, only eight years

following the imposition of a connection obligation. And with over 400 schemes

in operation in Denmark, more than 1.5 million homes, housing 60% of the

population, rely on district heating, supplied primarily by waste heat from

industry and incineration (86%). Schemes range in size from those catering for

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100+ homes in a small village to 100,000+ in larger cities (Danish District

Heating Association, 2008).

Whereas in Sweden, the success of district heating may be put down to the lack

of competition from natural gas until the mid-1980s in the central heating

marketplace (Werner, 1991). Furthermore, the heat density is high due to long

cold winters and the widespread use of wet central heating systems: these

being optimal requirements for implementing district heating networks. The

Swedish Energy Agency reported that renewable energy supplied 55% of the

country’s district heating needs in 2006, up from 24% in 1990, while the

Swedish District Heating Association’s statistics show that district heating,

which is available in every community with more than 10,000 residents,

provides 50TWh each

year and meets half the

nation’s heat demands.

All is not rosy, however,

as the breakdown by

type of building shows

below – many family

(detached) homes remain unconnected – this being germane to the majority of

dwellings found in north Stromness and Orkney more widely.

FIGURE 7: PENETRATION OF DISTRICT HEATING BY BUILDING TYPES

(SWEDISH DISTRICT HEATING ASSOCIATION, 2005)

At the opposite end of the public perception scale lies Eastern Europe. Here, a

study into combined heat and power plants (CHP) and district heating in Central

& Eastern Europe (CEE) (Bulgaria, Czech Republic, Estonia, Latvia, Lithuania,

Poland, Romania and Slovakia) was undertaken, examining plant

modernisation and improvement, increased use of biomass, and how expertise

in technologies might be transferred, for example, to China. According to the

final report:

… More than 40 million people in the CEE countries covered by these studies

are DH users and its share in the residential heat market is approximately 37%

Danish Technological Institute (2004)

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It was noted that heat demand in many CEE countries has fallen as industrial

production has declined, with being much of the heat provided by large-scale

fossil fuel plants there as in China, in contrast to the use of renewable biomass

(often with local small-scale CHP) in western and northern Europe.

3.2. Development of district heating in the UK

In 1979, a Department of Energy report (EP35) concluded that combined heat

and power generation associated with district heating systems could, in the long

term, be the cheapest method of heating buildings in UK towns and cities, and

make a significant contribution to meeting energy demand when oil and gas

supplies begin to decline.

A further report (EP53, 1984) undertook a feasibility study into the commercial

and technical aspects of implementing a programme of CHP-powered district

heating for nine major cities, viz. Glasgow, Edinburgh, Belfast, Tyneside,

Manchester, Sheffield, Liverpool, London, and Leicester. This report

recommended project plans be drawn up for at least two of these schemes, and

that the UK government should encourage the energy supply industry to

consider CHP heat distribution in their planning. However, at the time of these

reports being written, the energy industry was not yet privatised, and the

urgency engendered by oil shocks in the 1970s was beginning to fade. Of the

nine locations in the Department of Energy’s 1984 report, only Sheffield has

deployed a district heating scheme of significant size.

A more recent suggestion for district heating and cooling is one made by

London & Quadrant Housing Trust for the redevelopment at Gallions Park in

Docklands: this will include an Aquifer Thermal Energy System (ATES). In this

scheme, cold water would be drawn from an aquifer for cooling buildings in

summer and then, once warmed, passed to storage for re-use by heat source

pumps in winter to provide heating (London Development Agency, 2007).

However, the level of market share that district heating has in the UK heat

market is very low, lagging well behind the levels in most other European

countries according to Ecoheatcool (2006b) (see Figure 8).

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FIGURE 8: DISTRICT HEATING MARKET SHARE (ECOHEATCOOL, 2006B, PAGE 11) SOURCE: IEA

Somewhat surprisingly, perhaps, is the view that nearly twice as many private

houses in the UK may be connected to district heating as those in the social

housing sector. These data are provided as an estimate, which is

acknowledged as being subject to considerable uncertainty, and was first

published by Defra in 2007, and subsequently in BERR’s Heat Call for Evidence

(2008). It is apparent that, in the absence of major market players in the field of

heat supply, there is little reliable

data gathering or historical

reference data.

Nevertheless, as part of this research, an attempt to compile a detailed list of

district heating systems in the UK was undertaken. This can be found in

Appendix 3. The schemes range in size from a few flats through to several

thousands of homes and industrial sites – for the future might it be useful to

clarify how one differentiates ‘community’ and ‘district’ heating schemes?

3.3. Heat density and financial viability

District heating costs vary directly with density of housing and industrial process

heat requirements: if a large and cheap source of heat is available, the

competitive servicing of detached properties can, sometimes, be achieved. One

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example of this is Iceland where schemes are powered by geothermal heat, and

which has 85% of detached homes connected (Ecoheatcool, 2006a). On the

other hand, if alternative heating fuels or systems are cheaper then deployment

of a heating network may not be viable. Sullivan (2007) reminds us that the

planning system or legislation can, however, be used to encourage the inclusion

of networked heating in developments, as has been the case in Copenhagen.

This social engineering can deliver the heat density at which a network

becomes economically viable for a local Energy Service Company (ESCO).

4. HOUSING CONDITIONS 4.1. Stock survey of Scottish homes

This survey, carried out by the Scottish Government, is now undertaken on a

continuous basis rather than at fixed intervals as was the case prior to 2007.

Information and analysis in this thesis is based on the content of the 2007 survey,

these being the latest published data available.

The density of buildings being important to the viability or otherwise of district

heating schemes has already been mentioned: Error! Reference source not ound. shows that the number of detached homes being built has been increasing

since the First World War, while the number of new terraced homes and flats

continues to decline. The proportions of non-detached to detached have reversed

over time: which leads

to a direct impact on

energy use in that

detached homes have

more external walls

(with increased heat

loss) and larger

internal volumes

requiring to be heated.

This pattern is reflected in Stromness: the older part of the town being comprised of

homes, mainly terraced, huddled together in the lee of the prevailing winds –

whereas post-war houses are often detached, standing in larger garden grounds,

and in the case of the newest homes at Hamnavoe, fully exposed to winds from all

FIGURE 9: AGE & NUMBER OF DWELLINGS (SCOTTISH GOVERNMENT, 2007)

CRITICAL REVIEW


directions. It is the case, however, that these newer homes are more likely to have

better energy efficiency ratings than older properties, given improvements to

building standards.

4.2. Energy efficiency of existing buildings

Two methodologies for measurement are available: these are NHER (National

Home Energy Rating) and SAP (Standard Assessment Procedure). NHER

takes account of all energy use in a dwelling and is able to model regional

varations, whereas SAP focuses only on energy used for heating and hot water

(and which might be a useful consideration when modelling for a district heating

scheme) but ignores the impact of geographical influences. The Scottish House

Condition Survey (2007) reports that energy efficiency ratings in the social

rented sector tend to be higher than in other dwellings, with 17% of privately

rented properties rated as ‘poor’ – there being no incentive for landlords to

improve conditions as they receive the rent but tenants pay the energy bills.

4.3. Building standards in Scotland

The thresholds were raised in 2005, following the introduction of the Energy

Performance of Buildings Directive, with SAP being used to demonstrate that

dwellings meet Section 6 of the standards, and to provide Energy Performance

Certificates (EPC) for use in Home Information Packs since 2008 (applicable to

both new builds and older homes).

The EPC displays a dwelling’s current

and potential energy efficiency levels:

its design reflecting the energy

efficiency labels found on white goods

and already familiar to consumers.

Sullivan (2007) noted that if Scotland

were to adopt Swedish U-values for its

dwellings then space heating needs

would be reduced by 23%. These FIGURE 10: ENERGY PERFORMANCE CERTIFICATE

(DIRECTGOV, 2008)

CRITICAL REVIEW


savings could be further enhanced by improved airtightness standards and the

use of mechanical ventilation heat recovery systems, as propounded in both the

Code for Sustainable Homes and in PassivHaus standards.

4.4. Wind chill factor in exposed locations

Coastal communities on the north and west coasts of Scotland generally

experience a mild, wet, and windy climate, whereas those to the east

experience drier and colder weather. This combination of winter temperatures,

driving rain, and high wind speeds can result in a substantial wind chill factor

(see Appendix 5), with consequent increase in energy use. Heriot-Watt

University’s demonstration project in low cost, low energy housing for a high

wind and rain environment at Clouston’s Corner, in Stenness modelled a 31%

saving on space heating as being achievable in these conditions compared to

1998 Building Regulations.

4.5. Fuel poverty 4.5.1. Definition

The government sets this out in the Scottish Fuel Poverty Statement of 2002 as:

… "A household is in fuel poverty if it would be required to spend more than 10% of

its income (including Housing Benefit or Income Support for Mortgage Interest) on

all household fuel use." It goes on to say that ‘extreme fuel poverty’ is where

20% or more of household income is spent on fuel.

When, in 2008, kerosene was priced at 55p per litre householders with an

annual income below £13,000 would fall within this ‘fuel poverty’ definition.

4.5.2. Factors unique to peripheral communities

Transportation can add substantially to heating oil costs, despite lifeline ferry

services to many of island communities being subsidised by the Scottish

Government. This results in kerosene being at least 10% higher in the Orkneys

in comparison to mainland towns and cities (Orkney Islands Council, 2008).

CRITICAL REVIEW


4.6. Insulation grants and energy efficiency improvement schemes

With respect to buildings, the author of this thesis prefers to think in terms of

insulation poverty rather than fuel poverty, the latter term implying that if only

more money was available then more fuel could be bought and burned to provide

heat. Better that the requirement for heat is reduced by avoiding heat losses

through the use of insulation. Not only does this reduce fuel use, insulation is a one-

off spend in terms of money and embodied energy.

If Scotland is to lessen its dependence on energy-dense fossil fuels it must make

substantial energy efficiency improvements to enable the capacity of diffuse

renewable energy to meet and possibly maintain the living standards people have

come to expect. The latest government initiative, managed by the Energy Saving

Trust, and aiming to improve energy efficiency in buildings is known as the

Energy Assistance Package, replacing the earlier Warm Deal and Central

Heating programmes.

Energy Efficiency Advice Centres are available across Scotland for advice to

householders and businesses in gaining access to the Energy Assistance

Package. Divided into four stages, the package offers free advice on energy, on

how to claim benefits and reduced tariffs, provides insulation to qualifying

homes and householders, and heating systems in certain circumstances.

CRITICAL REVIEW


5. PLANNING STROMNESS 5.1. Orkney Local Plan

Orkney’s second largest town, Stromness (population ~1,600) was deemed to

require an additional 140 homes by 2010 (Orkney Islands Council, 2004). This

was to be satisfied by the designation of a number of potential sites within the

existing settlement boundaries, subject to development of infrastructure to

permit access and provision of water and sewerage services. Areas identified

for new housing are marked H1-H6 (Error! Reference source not found.) while those for industrial sites are at B3 and B4. The estimates of potential for

new dwellings is:

H1: suitable for approx 60 sites; to date, 16 dwellings constructed and occupied H1: suitable for approx 60 sites; to date, 16 dwellings constructed and occupied

(August, 2009).

H2: constrained by flood path, may be suitable for up to 16 dwellings.

FIGURE 11: STROMNESS, ORKNEY (ORDNANCE SURVEY, 2009)

CRITICAL REVIEW


H3: undeveloped brownfield land suitable for 8 dwellings.

H4: not available for housing development.

H5: 24 dwellings have been provided by Orkney Housing Association on

southern part of this site; there is scope for further development to north.

H6: road access improvements required before development could proceed.

5.2. Urban Design Framework

The Stromness Urban Design Framework (Orkney Islands Council, 2009a)

aspires to improve the local amenities with suggestions as to the addition or

replacement of a number of buildings in the area surveyed as part of this

research. The proposals are for the regeneration of Stromness Pierhead to

feature a new library, a new Primary School to be built at the current Lorry Park

site (site R1, Figure 12: Proposals Map 2 - Stromness (Orkney Local Plan,

2005b)), the redevelopment of Stromness Auction Mart site to deliver a

replacement supermarket

for the Co-operative

Society (site R2), Orkney

ZeroWaste’s earthship

and composting project

to south of Hamnavoe,

and construction of

additional affordable and

sheltered housing. This

framework makes

reference to a district

heating network as

having a role in the future

development of

Stromness.

FIGURE 12: PROPOSALS MAP 2

- STROMNESS (ORKNEY LOCAL

PLAN, 2005B)

RESEARCH AND RESULTS



6. ENERGY SURVEY

A survey was undertaken to understand energy use and housing conditions in

the northern area of Stromness. Similarly, approaches were made to local

companies and organisations that had potential to provide renewable heat or

energy resources to the community.

Using the information gained, a number of scenarios were modelled to establish

the criteria under which a viable district heating scheme might be implemented

in a coastal community such as Stromness.

6.1. Heat demand satisfaction

Consumers may satisfy their heat demand directly through ownership and

operation of generating equipment such as a boiler or stove using natural gas

(mains connected, continuous flow) or kerosene, coal, wood, LPG, or other

fuels delivered in batches, or electrical heaters (mains connected, continuous or

timer regulated flow). Availability of fuels may vary between locations, and

noting that many of Scotland’s rural and coastal communities being off the

natural gas network.

In a fossil-fuel constrained world, some of these fuels and methods of supply

are likely to become overly expensive or obsolete, while the renewable energy

supply chain is a longer-term sustainable option but yet to be fully realised.

As an alternative, a domestic consumer may choose to purchase on-demand

heat under contract from a district heating scheme operator through direct

connection to their renewable energy network, or by means of a boiler or CHP

leasing scheme where the plant is installed on their (usually, industrial)



premises. Furthermore, newer technologies such as solar thermal may be used

to supply some or all of the consumer’s hot water needs.

6.2. Survey area

The Department of Energy & Climate Change makes available an interactive online

heat map to aid power station developers. However, no data are available for

Stromness thus requiring primary research be undertaken for this thesis.

The map below shows the boundaries of the area surveyed: the decision to focus

on this area was due to the ease of access should a district heating scheme

network require to be installed. On reflection, however, the heat density and

demand in the older part of Stromness is likely to be much higher, thus making a

district heating scheme more financially viable long-term.

Conversely, pipework installation in the southern area of Stromness would incur

higher initial construction costs, project time, and disruption to community life. There

exists the possibility of difficulties being encountered due to the area’s conservation

status and likelihood of trenches encountering granite, being inundated by sea

water, or constrained by space available under the roadway.

FIGURE 13: STROMNESS - SURVEYED AREA



6.3. Key requirements for connection to a district heating scheme

6.3.1. Heat users

Buildings with a wet central heating system comprising radiators (or, depending

supply temperatures, underfloor heating coils), or without hot water storage

tanks, are most easily connected to a district heating network – nearly half the

homes in the survey area met one of these criteria. These are likely to

experience the least disruption to service and lowest connection costs, as only

the installation of a heat exchanger would be required to link into a DH network.

6.3.2. Heat providers

Local businesses and organisations with capacity to provide both demand from

and waste heat to a district heating scheme in Stromness were identified: a

survey form was supplied to each, but the absence of responses disappointing.

During the period of this research, Orkney Islands Council announced an

Invitation to Tender for a district heating feasibility study in north Stromness: as

a consequence the author was less persistent than might have been expected

in following up non-responses from local businesses out of concern at possibly

compromising the forthcoming commercial tender process and feasibility study.

6.3. Questionnaire design

Qualitative and quantitative research was required to establish which systems,

fuels, consumption levels, and geographic locations, were present in the north

end of Stromness. Two versions of a standard questionnaire were designed;

one for completion by domestic householders, the other for commercial and

industrial business users. The design was trialled and revised to encourage

completion: using images to prompt responses, and a number of closed

questions to make it more straightforward for participants to answer. The most

difficult open questions relating to annual fuel use were positioned at the top of

the second page – working on the presumption that by this stage respondents

would have already committed to the research and be more willing to locate

their energy bills and provide the necessary answers. Although this device was

not wholly successful an overall response rate of 26% from householders was

achieved.



6.4. Response rates

Responses were received from 66 of 250 questionnaires distributed to domestic

properties – a return rate of just over 26%.

Of the six forms delivered to industrial and

commercial organisations, some of whom

are heat producers in Stromness, none

were returned. A second, more direct,

approach was made to some but data

acquired was scanty.

6.5. Property sizes and heating regime

Thirty responses were received to questions regarding the number of rooms in

each property and the number heated. It was noted that nearly 30% of

homeowners choose to heat only one room in their property.

Ranging from single room

properties to one with twelve

rooms, with three to five rooms

being most common (Figure 14),

it appears that, on average, just

over 50% of rooms in a home

are kept heated.

6.6. Fuels and technologies

The fuels and technologies

used for heating and hot

water are presented in the

graph (right): note that a

variety of these may be found

in each home, giving rise to a

total higher than the number

of questionnaires returned.

FIGURE 14: NUMBER OF ROOMS IN HOUSE

FIGURE 15: NUMBER OF ROOMS HEATED IN HOUSES

FIGURE 16: FUELS & TECHNOLOGIES IN USE



6.7. Heat loss from buildings

Figure 17 displays the heat loss routes from buildings, indicating the costs of

forestalling them, and the annual savings, based on figures from the Energy

Saving Trust in 2007, while Figure 18 makes visible to us heat being transmitted

in the absence of wall insulation.

FIGURE 17: HEAT LOSS & INSULATION (DEAC, 2007)

FIGURE 18: THERMAL IMAGE (PRESS ASSOCIATION, 2008)



6.7.1. Insulation

Given the earlier information in Figure 17 with regard to heat loss, the low levels

of wall insulation shown in Figure 19 suggest there is substantial scope for

improved energy efficiency in Stromness. However, it is possible that responses

may understate the levels of insulation in that homeowners can be unaware as

to whether their walls are of cavity construction, or insulation installed.

FIGURE 19: HOME INSULATION LEVELS

6.7.2. Loft insulation

Of the 59 positive

responses to the

question on loft

insulation, only 29

(or 49%) stated the

depth installed.

This is depicted in

the histogram, and

shows that, at best,

fewer than one in

10 homes meet or

exceed the Energy Savings Trust’s recommended loft insulation depth of

FIGURE 20: DISTRIBUTION CURVE OF DEPTHS OF LOFT INSULATION



270mm. There may be a number of reasons for this, including roof space

design or loft access: further research would be required to confirm these. It is

apparent too that many lofts were insulated to earlier standards and have not

been revisited to meet latest recommendations.

6.7.3. Double glazing and draught proofing

Over 80% of homes returning the survey were fully double glazed, rising to

nearly 90% when those with some double glazed windows are included.

Although the percentage with double glazed doors is lower than that of

windows, the author noted while delivering survey forms that the entrance doors

of many homes do not open directly outdoors but into porches, which act as a

form of draughtproofing, although no statistics were recorded. It appears that

draught excluders at doors are preferred to heavy curtaining.

As a follow-up to this survey, it would be useful to investigate why homeowners

chose to install expensive double glazing throughout their property, while

omitting to install wall or other insulation. Is this the result of high-pressure sales

teams operating in only one sector of the market?

FIGURE 21: DOUBLE GLAZING & DRAUGHT PROOFING



7. POTENTIAL ENERGY SOURCES

The Scottish Government’s emphasis on providing renewable heat from

biomass overlooks not only the limits to growth of sufficient material locally but

also the variety of other energy sources that might better suit particular locales,

may have a lower environmental footprint, or become available through

judicious use of funding mechanisms.

As part of this study, research into a number of other options that might be

available was undertaken and is reported. The following factors were among

those considered: availability of resource, environmental impacts, cost per kWh

of energy to the consumer, and technical or operational difficulties.

7.3. Heat sources 7.3.1. Large scale power plants

Based on research commissioned from University of Southampton, the

Institution of Civil Engineers’ report ‘Why Waste Heat’ explains how the capture

of waste heat from large power stations such as Drax, Ferrybridge, and

Kingsnorth, could feed into district heating schemes serving nearby densely

populated conurbations. The work by James and Bahaj (2009) suggests that, by

2020, up to 5% of UK’s heat demand could be met from this resource alone,

subject to the replacement programme for older power stations being planned

to integrate CHP plants and district networks. Within coastal communities, this

concept might be adapted to Kirkwall or even Flotta, and is being actively taken

forward in Lerwick, whose 40% efficient fossil fuelled power station is adjacent

to the district heating plant.

7.3.2. Small scale power plants

On a smaller scale, it is common for boilers and CHP plants within schools,

hospitals, and industrial premises (be they fossil fuel powered or running on

renewable energy sources) to be integrated within district heating networks.

These provide substantial flexibility in meeting fluctuating demands, build

redundancy across the network, and maximise load factors and thus efficiency.



In Stromness, there are several businesses with waste process heat: these

include Tod’s of Orkney (bakers of oatcakes), Orkney Herring and Orkney

Fishermen’s Society (both have high cooling demands, with heat being emitted

from refrigeration systems), and Orkney Fudge/Argo’s Bakery (currently under

redevelopment), while the local swimming pool recycles its heat, gained from a

ground source heat pump.

7.4. Biomass

Very much the favoured fuel for renewable heat under the Scottish Government’s

proposals, biomass systems will only be competitive with their fossil fuel

counterparts when widespread supplies are available at cost-effective prices. The

security and volatility of this supply chain is important with respect to this thesis in

that both domestic and large-scale industrial consumers in the UK are being

encouraged to switch to biomass.

7.4.1. Willows and short rotation coppicing

The climate and conditions in Orkney do not generally support the growth of

trees as biomass. Despite this, the Agronomy Institute at Orkney College in

Kirkwall has embarked on the Pelletime programme of research with the

Northern Periphery grouping of universities and institutes. This academic

consortium seeks to identify suitable species for biomass production and

pelletising. Studies being undertaken in Orkney include the growth and short

rotation coppicing of willow and poplar clones, and the potential of C4 grasses

such as reed canary grass to become a biomass crop.

Simultaneously, a local farmer has chosen to plant four hectares of willow on

prime agricultural land, and aims to harvest one hectare each year on a rotating

basis to provide heating for his own home. The process involves cutting the

‘rods’ of willow and leaving them to air-dry before chipping prior to burning.

Although labour intensive at small scale, there is potential to industrialise should

large areas be devoted to biomass. An ongoing concern is the footprint of lands

to be taken out of food production to meet and deliver our energy demand.



7.4.2. Other biomass crops

Grass cuttings, straw and peat are further sources of biomass considered to be

available to many coastal communities, including Stromness. However, the

displacement of straw from animal bedding to fuel may provoke animal welfare and

substitution issues, while the drying and burning of peat not only releases large

amounts of carbon dioxide and methane but its removal can have negative impacts

on biodiversity and landscape generally. Furthermore, peat cannot truly be

considered a renewable resource – its replenishment rate being low to zero.

During the summer months, cutting and collection of grass and verges under

contract to Orkney Islands Council produces 4 tonnes of material daily, which is

composted over a period of 24 months at Bossack Quarry. This might instead

become a feedstock for anaerobic digestion, given that animal slurry volumes are

reduced as cattle graze outdoors throughout the long daylight hours.

There may in some communities be potential for planting of additional biomass

crops in set-aside or brownfield sites. However, issues of biodiversity, costs and

ease of harvesting, and other variables would need to be investigated on a species

case-by-case basis to confirm financial and biological viability of proposals.

7.5. Heat pumps

Increasingly being installed at domestic level, heat pumps (air, ground, or water)

can provide Coefficients of Performance up to 5 or 6, depending on temperature

differentials between input and output. By capturing and concentrating the heat

energy (i.e. stored solar energy) present in the source medium by means of

compression, this technology offers many benefits.

The potential for pollution from gases used in compression and from anti-freeze

liquid present in the ground loops needs consideration: a number of equipment

manufacturers are replacing refrigerant gases such as the HFCs (ozone-

depletors, although less so than their predecessor HCFCs) with CO2 (referred

to as R744) or ammonia. In situations where deployment of a water heat source

pump is possible, the ground loop can be replaced by direct pumping of water

from river, lake, or sea through the heat pump.



For heat pumps to be considered a renewable energy technology, the electricity

required by compressor and pumps must also come from renewable resources.

7.5.1. Ground

The water in the swimming pool at Stromness is warmed by heat gained from the

grounds opposite where the loop for its ground source heat pump is buried. On a

visit in June, the manager demonstrated its operation, confirming that a minimum

Coefficient of Performance of 3.3 was being achieved, and that the oil boiler had

been switched off completely.

7.5.2. Sea water

In the Netherlands, The Hague and Vestia Housing Corporation plans to use a

heat exchanger and seawater heat source pump (ammonia-based) which will

be deployed in the North Sea to pre-warm water in their network from 4°C in

winter to 11°C prior to circulation to 750 households in the town of Duindorp.

Each home has an individual ground source heat pump to raise the water

temperature to 45°C for heating and 65°C for hot water.

Average sea temperatures in Orkney range from 5 to 12C during the year

(Hughes, 2005). It was calculated, during an earlier

assignment, that a large scale heat pump, using

CO2 as its refrigerant would operate at a Coefficient

of Performance of approx 2.5.

7.6. Anaerobic digestion

Anaerobic digestion is a biochemical process in which organic materials are

broken down in the absence of oxygen, thereby reducing the level of toxins,

FIGURE 22:SEA SURFACE

TEMPERATURE DATA - 2002

(BLUE) & 2003 (RED),

(HUGHES, 2005)



odours, and microbial activity, and producing biogas (which consists of

methane, carbon dioxide, and hydrogen sulfide).

Bio-wastes suitable for treatment using anaerobic digestion include animal

slurry, animal and fish by-products, green agricultural and municipal wastes

(including foodstuffs), and human sewage. Slurry is defined as

…a mixture consisting wholly of or containing excreta, bedding, feed residues,

rainwater and washings from a building or yard used by livestock, dungsteads

or middens, high level slatted buildings and weeping wall structures, or any

combination of these, provided such excreta is present.

Scottish Government (2003).

Diversion of these from waste stream not only makes them available as an

energy resource but can also cut costs of disposal (through avoidance of gate

fees) and reduce the risks of pollution on land and in the marine environment.

The inclusion of some types of wastes may require PPC or waste management

licensing by SEPA.

Current restrictions on the use of resultant digestates may, however, act as a

deterrent to the inclusion of some of feedstocks. Late in 2008, the European

Commission introduced a Green Paper looking at the management of bio-waste

(up to 139 million tonnes arise annually in the EU, and are a significant source

of greenhouse gas emissions when not properly treated). The Commission

seeks to develop further legislation, if appropriate, extending the definition of

bio-waste and to ensure separate collection of each material. Introduction of a

quality assurance scheme for compost and digestate arising from treatment of

bio-waste, including supply chain traceability, and a labelling system with

defined quality standards to build consumer confidence, are proposed.

7.6.1. Qualified potential

Recognising the potential of this technology, the UK government appointed an

Anaerobic Digestion Task Group in March 2009 to deliver the following goal:

“By 2020 anaerobic digestion will be an established technology in this country,

making a significant and measurable contribution to our climate change and wider



environmental objectives. It will produce renewable energy in the form of biogas

that will be used locally or injected into the grid for heat and power and for transport

fuel. At the same time, it will capture methane emissions from agriculture. It will

also divert organic waste, especially food waste, from landfill. The digestate will

provide organic fertiliser and soil conditioner for agriculture and land use. Anaerobic

digestion and its products will be used in a way that is both beneficial to the

environment and cost effective for that particular location.”

Defra (2009).

However, the experiences of Orkney Meats, who installed an anaerobic

digestion plant to handle blood products, and had both equipment and supplier

fail to perform, and that of Highland Park Distillery’s investigations into the

potential of AD systems in the late 1990s, have been less than positive. It is

clear that the process is reliant upon stringent management of many variables

including feedstock consistency, pH, water content, temperature, and gas

withdrawal rate (Water Pollution Control Federation, 1990).

7.6.2. Farmyard waste

A visit to Tuquoy Farm on Westray

in May 2009 was undertaken to

inspect anaerobic digestors being

operated by Colin Risbridger. The

main digestor (pictured, right)

processes animal slurry from the

slatted courts (outlet pipe

pictured,below) where cattle are

housed for seven or eight months

each year.

According to the operator, this produces approx one cubic metre of biogas per

cow per day (two-thirds of which is methane, equivalent to

5.8kWh at 85% efficiency). This anecdotal figure has been

corroborated by reference to calculations undertaken by

the Agri-Food and Biosciences Institute (2009).



The digestor operates within the mesophilic temperature range, being

maintained at ~35°C by a heater running on methane produced during

digestion. The detention period within the digestor ranges from 10 to 20 days

depending upon feedstocks and operating temperature. As the biogas is

produced, impurities such as H2S and CO2 are removed, before the methane –

CH4 – is piped to two 10kW generators to produce electricity. It is planned to

export to grid when electrical connections are fully stable and operational.

Experiments to digest crab shell waste from the fishing industry are ongoing.

As a potential source of renewable energy this technology shows much promise

for use in areas such as Orkney. With up to 80,000 cattle being kept indoors

during the months when demand for heat is high, methane could be generated

at farm level and collected – as is done with milk production, for example – for

use in a CHP plant or domestic gas boiler.

7.6.3. Waste water treatment and human sewage

Although most town sewage treatment plants, such as that of Stromness on the

shore of the Bay of Ireland, are modest in scale, they might offer a further

opportunity for production of renewable energy. United Utilities announced it is

commissioning a biomethane project at the Davyhulme waste water treatment

works in Greater Manchester, where anaerobic digestion of human waste from

1.2 million people will produce biogas (Wardrop, 2009). The methane will be

piped into the natural gas grid from 2011 to supply up to 5,000 homes, used in

the company’s tankers, and supply electricity to run the plant.

Recently upgraded, the Stromness site uses activated aerobic digestion to

handle between 600 and 1800 tonnes of waste water per day (the volume is

high as the majority of foul and storm drains are combined). Being the opposite

to anaerobic digestion, the process minimises generation of methane and

produces significant quantities of hydrogen sulfide. Each week 40 tonnes at 5%

solids is transferred to Kirkwall’s Head of Works for final treatment, joining

waste from a number of other plants, while around 1,000 tonnes of digestate is

returned to the land each year.



It is to be hoped that water companies will consider anaerobic digestion when

installing or upgrading plants in future – if a market for the methane is created

then this may provide the necessary incentive to invest.

7.6.4. Seaweed – biomass for anaerobic digestion

An exhibition at the Westray Heritage Centre in 2008 focused on the history of

the kelp industry’s rise and fall in the Northern and Western Isles of Scotland;

with harvests being sent south to the chemical works in the industrial central

belt and profits to the landowners’ pockets. Those islanders who collected and

burned the seaweed to produce the valuable ash worked long hours in difficult

conditions, while smoke polluted the local atmosphere.

A research programme at the Scottish Assocation for Marine Science near

Oban is investigating seaweed as a potential feedstock for anaerobic digestion

and production of biogas for coastal communities. In its favour, seaweed does

not contain lignin: this is present in vegetation grown on land and is slow to

breakdown. It appears to be an ideal resource, being abundant and not

competing for space with food crops. However, its role in the marine biological

cycle needs to be better understood before embarking on wholesale harvesting

– this, and how to harvest and process such bulky material cost-effectively will

be researched in the coming years.

7.7. Energy-from-Waste

Some of the energy

that drives Shetland

Heat and Power Ltd’s

district heating

scheme is derived

from the incineration

of 23,000 tonnes of

municipal wastes

annually (Martin,

2007) from Shetland

and Orkney, wastes

FIGURE 23: LERWICK DISTRICT HEATING (MARTIN, 2007)



from visiting cruise ships, and North Sea drilling muds.

Although individuals and businesses alike are being encouraged to reduce,

recycle, and re-use, within the waste hierarchy, the risk to this fossil-fuel derived

supply chain is low. Demand for heat energy in Lerwick is growing; the author

having seen a third oil boiler recently installed at Easter 2009, and being told

that the waiting list to join the network has now been closed to new applicants.

7.7.1. Material excised as provided ‘commercial in confidence’

7.8. Backup options - wind to heat and solar thermal

The renewable energy sources examined in this thesis as having potential to

power a district heating network in a coastal community may be susceptible to

having their availability disrupted from any number of causes: for example,

disease could render biogas production difficult or biomass may become overly

expensive or in short supply. By diversifying the supply of heat to the network,

the system can be made more robust and flexible, although certain to incur a

capital expenditure penalty to deliver this.

In situations such as Stromness, with excellent wind resources, the option of

wind to heat to maintain the temperature of stored hot water for use at peak

periods might be appropriate; while the deployment of solar thermal panels on

larger south-facing buildings to act as back-up in meeting the summer hot water

demand from tourists staying in local hotels might also be considered.



8. MODELLING OF HEAT DEMAND AND SUPPLY

Performance of renewable heat technologies within a district heating network

can be affected by factors such as seasonal or diurnal fluctuations of the

heating (and cooling) demand, which may ultimately compromise the plant’s

financial viability. Other characteristics having influence include size of heat

load, choice and availability of fuels, equipment load factor, adaptation or

replacement of existing heating systems, and suitability of particular

technologies to its operating environment.

8.1. Maximum local heat demand

From research undertaken by survey and interview, a month-by-month demand

profile for energy requirements for space heating and hot water was prepared,

being modelled using degree days information from a rolling 20-year average.

The profile is based on data provided by the following premises in north

Stromness: assuming both a substantial increase in new homes and all those

surveyed will at some stage connect into a district heating network:

For consumers

currently using

electricity to meet

heating and hot water

needs, it has been

assumed that all kWh

charged on Economy 7

FIGURE 24: HEAT DEMAND PROFILE, NORTH STROMNESS

FIGURE 25: TARGET CONSUMERS IN STROMNESS



tariff would be supplied through the district heating network in future.

An assumption has been made that the new primary school will use 50% less

energy than the existing 1970s building, and that an arbitrary 84% of the

daytime use of electricity by Orkney Herring is used for heating/cooling (and

thus could potentially be provided by the district heating scheme).

The table below provides a breakdown of this overall demand, and the means

that might be employed to satisfy this, including the sizing of plant and fuel

requirements for biomass, anaerobic digestion, and heat pump options. It is

evident from the number of cows required to produce sufficient methane to

maintain current levels of heating in one area of Stromness how dependent our

society is on energy dense fossil fuels in meeting its heating requirements, and

how vulnerable it may become.

8.2. Phased construction and connection

The previous section looked at the overall demand should all properties be

connected to the network. In reality, this is unlikely – Lerwick’s district heating

network supplies 30% of the town’s heat demand (62% of supply is to industrial/

commercial users) and has taken 10 years to reach this level of penetration.

The rate at which new and existing properties (and their relative locations) may

seek to connect to a district heating network requires to be factored into

calculations for sizing power plant and pipework. A review of construction

progress against the local plan (Orkney Islands Council, 2004) suggests that it

FIGURE 26: OVERALL MONTHLY HEAT DEMAND AND POTENTIAL MEANS OF SUPPLY



would be prudent to assume that, on average, not more than 20 new homes

annually may be connected to the network during the initial twenty years of the

plant, while replacement rates for existing heating systems may range from only

5% to 7% of existing stock (MVV Consulting, 2007). Developing a mechanism

to encourage take-up of district heating locally may be limited by both these

factors, unless either an attractive pricing regime or compulsion can be used to

build up the customer base.

Re-applying the model used earlier but assuming only 40 properties connect

initially (20 new homes, 10 oil central heating users, 10 storage heating users)

produces the following requirements for energy. As before, the various methods

of supplying demand are modelled and presented alongside.

FIGURE 27: PHASE 1 HEAT DEMAND AND SUPPLY



9. COSTINGS

Although district heating is a well established technology, the lack of experience

and implementation skills in the UK, particularly in more remote communities,

will add to costs by requiring the importation of personnel and equipment, often

at a currency disadvantage. At the same time, the raising of finance for new

plant and covering of operational costs is becoming more difficult during the

global recession, but the scale of opportunities elsewhere in the world,

exemplified by China and the USA, is proving to be more attractive to

manufacturers and suppliers alike, vide Vestas.

From a study by Poyry (2006), the levelised cost of biomass grid connected

heat displays a large range, due to the different costs of various biomass fuels

and their high transport costs depending where they are sited.

The majority of the cost of a district heating system comprises the insulated

pipework, heat exchangers, and civil engineering. Heat exchangers range in

price from £750 to £1,000 for domestic properties, while those for commercial or

industrial buildings may cost between £10 - £15,000.



9.1. Infrastructure

BSI definitions, calculations, and specifications for district heating schemes

have been published: a particularly relevant standard when engineering a new

plant is BS EN15316-4-5:2007 – Heating systems in buildings – Method for

calculation of system energy requirements and system efficiencies – Part 4-5:

Space heating generation systems, the performance and quality of district

heating and large volume systems.

9.1.1. Anticipated lifetime of plant and network

It is commonly held that the heating plant life is expected to be 25 years, while

that of the pipework is 40 years. Increasingly, pipelines are made from plastic

rather than metal: this may impact on longevity but there is no evidence as yet.

9.1.2. Pipework

Insulated pipes for district heating networks are required to meet EN 253 /448

standards. QA certification guidelines are available to pipework suppliers and

manufacturers for most standard combinations (Euroheat & Power, 2007), while

manufacturers will recommend minimum distances below roadway which must

be maintained to avoid damage from passing traffic.

FIGURE 28: PIPEWORK BURIAL (UPONOR, 2007)

The move to plastic pipelines allows for faster deployment as, unlike metal

pipes, they can be cold laid and trenches backfilled quickly. Metal pipes need to



be tested with water heated to operating temperature and pressure, with

excavated material being stored offsite until this is completed. This method

incurs longer disruption to traffic as trenches remain open.

The Energy Saving Trust

report, Power in Numbers,

provides a useful cost per

dwelling guide to

connection charges, which

further highlights the

benefit to district heating

operators of seeking to

recruit properties such as

apartment blocks, or possibly

schools, with high heat density to their networks.

This is supported by Swedish research on district network connection charges

for widely dispersed properties in a number of locations, which provided details

of costs (in euros) per house (Nilsson et al, 2008) – the nature of properties in

north Stromness would be similar to many of those in this study.

FIGURE 30: PIPELINE COSTS IN SWEDEN (NILSSON ET AL, 2007)

9.1.3. Heat exchangers

District heating networks may operate as an open, or direct, system whereby

heated water is pumped through radiators and hot water systems in buildings as

FIGURE 29: BUILDING DENSITY AND CONNECTION COSTS

(ENERGY SAVING TRUST, 2008)



has been the practice in Eastern Europe and Russia. This mode of supply,

however, can produce pressure fluctuations in domestic pipework should the

relative altitude of properties across the network differ. The alternative, an

indirect or closed system which uses a heat exchanger to separate the water in

a customer’s circuit from that of the district heating network, is the more

common method of heat supply in modern installations.

FIGURE 31:

HEAT

EXCHANGER

(UTILICOM,

2008)

9.1.4. Heat meters

BS EN 1434-6:2007 is the relevant standard for the installation, commissioning,

operational monitoring and maintenance of heat meters. The meter is installed

within the heat exchanger unit, and can be read remotely by the operator of the

district heating network to provide customer invoices for heat used.

9.2. Financial support mechanisms 9.2.1. Renewable Heat Incentive

The Energy Act 2008 allows for the setting up of a Renewable Heat Incentive

(RHI) although details have yet to be formally agreed. These are anticipated

during the latter half of 2009 – but it has been suggested that incentives may

not become payable until 2011.



Funded by a levy on fossil fuels, it is proposed that incentives will apply to all

scales of renewable heat generation and encompass biomass (including CHP),

biomethane, biogas (from anaerobic digestion) and heat source pumps. The

incentive may be banded according to the factors above, and payment

arrangements may vary.

9.2.2. Enhanced Capital Allowance

The UK government seeks to encourage business in minimising its

environmental impact by providing tax relief on capital purchases to companies

through the Enhanced Capital Allowance scheme. To qualify, the equipment

being purchased must meet defined energy-saving criteria and be on the list of

certified eligible products. For example, the Coefficient of Performance of an

approved heat source pump should exceed 4 in order to qualify for tax relief on

purchase cost – a sea water heat source pump deployed in Stromness may

achieve a CoP of 2.5 depending on operating conditions and thus be ineligible.

The Energy Technology List, which sets out these criteria and products, is

published annually, with monthly updates to the product list being posted to the

ECA’s website at www.eca.gov.uk



10. OPERATING STRUCTURES

A wide range of governance models are available to the district heating network

operator: from local

authority or social

landlord ownership, to

private sector ESCOs,

community-led

organisations, or

bodies supported by

Co-operative

Development

Scotland. Sweden, with its

tradition of district heating, and use of laws and taxes to promote it in

preference to fossil-fuelled heating systems, has seen a shift from public to

private sector ownership of schemes over the last ten years.

Given the high capital costs in initiating district heating networks in smaller

communities, some thought at policy level will be needed to incentivise projects:

the market potential is unlikely to find favour with an unsubsidised private sector

when opportunities exist in cities or dense suburbs, be they coastal or not.

FIGURE 32: OWNERSHIP MODELS IN SWEDEN (ECOHEATCOOL, 2006A)

DISCUSSION


DISCUSSION

Last century, the production and generation of gas in the UK was undertaken by

privately owned or municipal companies, until they were nationalised under the

Gas Act in 1948 by the post-war Labour government. This, under the aegis of

British Gas, was then dismantled by the privatising policies of the Conservatives

under Thatcher nearly forty years later, in 1986. The electricity industry followed

a similar path, with privatisation demerging the National Grid (responsible for

distribution) from the Central Electricity Generating Board in the 1990s.

Responsibility for power generation was sold off to a number of private sector

companies, once the government underwrote issue of ageing nuclear power

plants to the business sector’s satisfaction. Although the industry is nominally

liberalised, competition and consumer choice remains an artificial construct, in

that it requires the intervention of Ofgem to ‘manage’ the market and protect

against oligopolistic abuse by the private sector.

Why is the foregoing important?

The author of this thesis thinks it is essential we remind ourselves of the

benefits and pitfalls that lie in wait when devising energy policy for the future

and recalling that market manipulation may not produce the outcomes sought.

In the latest drive for a holistic approach, the EU no longer sees energy

efficiency and renewable energy as mutually exclusive subjects but as the two

halves of ‘sustainable energy’. In this scenario we are encouraged to reduce our

energy requirements first, thus enabling renewable energy – garnered from less

energy dense sources – to meet our lower demand.

However, this approach introduces a tension to decision-making regarding

district heating schemes – that of energy efficiency versus the high heat density

required to support capital and operating costs. If homeowners insulate their

homes to meet the latest advice, will they then require to purchase sufficient

DISCUSSION


heat to keep the scheme financially viable? Or will this push up the unit price of

heat to such a level as to discourage others from joining, and continue to burn

fossil fuels instead? A detailed study to identify the optimal intersection between

all three competing criteria would prove beneficial in supporting investment

decisions.

Or might the owner, surrounded by their fully insulated home, succumb to the

Khazzoom Brookes postulate and decide to heat all their rooms, or turn up the

thermostat a few degrees, thereby enjoying additional thermal comfort while

maintaining their heating bills at the same costs as prior to insulation being

installed? Despite significant improvements in vehicle fuel economy, the

addition of energy-consuming gadgets such as air conditioning and in-car

entertainment systems has nullified the gains in miles per gallon – is this likely

to be repeated in the home insulation market? Few post-occupancy evaluation

studies of new buildings have been completed to confirm their energy

performance – might there be scope to review behavioural changes in newly

insulated homes as a predictor of energy demands of the future?

Furthermore, despite a number of documents emanating from the Scottish

Government in support of planned infrastructure and developer contributions,

‘planning gain’ is not routinely applied as the concern is that these measures should

not be cost prohibitive to those bringing forward plans for new homes. If we are to

build communities in which district heating networks run on renewable energy

sources, then who will provide the infrastructure and how will it be funded? Perhaps

a study of European district heating schemes would provide ideas and answers that

might be relevant to the Scottish situation .

On the planning front, there is an apparent clash between the conservation lobby

and the drive for energy efficiency in buildings. The costs of meeting the planning

department’s expectations with regard to conservation of a building’s outward

appearance can result in effective energy-saving improvements not being

implemented by homeowners, or an exemption from building regulations being

granted. The author of this thesis understands that an academic at Napier

University is studying the implications of this contradiction.

DISCUSSION


Having considered some of the potential renewable energy sources available to

a coastal community, the practicalities of accessing and dsitributing these

requires some attention.

For example, given the technical challenges of maintaining anaerobic digestion

of animal slurry might there not be a case for an organisation to offer modular

AD units for deployment on-farm, with specialist remote in-tank monitoring of

conditions supported by an area manager with expertise (as Scottish Water

does with its sewage plants)? Thought might also be given to whether potential

exists for conversion of existing slurry tanks into anaerobic digesters through

the addition of heaters and pipework. Should a network of AD plants become a

feasible option the development of a biogas tanker service will become

essential. Finally, might the expansion of AD allow for the construction of a gas

network, rather than a district heating one, in smaller communities – an example

of this is Lunan in Germany.

For large-scale reliable generation from renewable sources, the concept of sea

water heat source pumps holds much attraction for the author of this thesis. In

the longer-term, it may be possible to drive the pump using electricity generated

from the local tides, thus providing an assured source of energy for the

community. However, although there are a number of technical challenges to

overcome in the interim this solution could prove to have potential to address

some of the remaining 89% of heat demand post-2020.

In the meantime, improving the energy efficiency of people’s homes is a quick

win for everyone. The results of the survey with regard to the levels of insulation

in homes makes one realise how little progress we’ve made. Simple and

effective steps such as providing homeowners with a visible record of their

home’s heat loss by means of a thermal imaging camera might encourage

uptake of insulation products, or by extending grant schemes still further.

Alternatively, more draconian steps may be required: these need to be easy to

understand and implement and might include stamp duty at point of sale, or

changing the energy supplier’s tariff to reward lower energy use – but these

carry a risk in that they may deliver more people into fuel poverty and must

therefore be linked to access to insulation or other improvements.

DISCUSSION


So what are the benefits of district heating to a community?

They include simple and reliable delivery (always on), less floor space required

for own heating equipment (no boiler or fuel tanks), less capital investment in

your own heating equipment (once you have radiators installed), and a lower

fire risk as no fuel use in dwellings.

And the disadvantages?

Sweden’s experience (Nilsson et al, 2008) indicates that unless 70% of a low

density community is connected then the financial viability of a scheme may be

in jeopardy, and connection costs may exceed those of installing your own

equipment, such as a biomass boiler or ground source heat pump. Figure 33

affirms the importance of high heat density to a scheme’s success.

FIGURE 33: HEAT SOURCES IN SWEDEN (NILSSON ET AL, 2008)

CONCLUSIONS


CONCLUSIONS

If Scotland is to fulfil 11% of its 2020 heat demand using renewable energy sources

then the government must focus its attention on locations with either the highest

heat densities or the largest available heat sources, and preferably both, as a

means of reaching the target. With up to 5% of the UK’s heat demand capable of

being met by waste heat from major power plants (Institution of Civil Engineers,

2009) and 17% from Energy-from-Waste (Martin, 2007) it’s essential that these be

utilised wherever possible through district heating networks (or at worst for

generating electricity for heat). However, it must be noted they cannot be classified

as renewable energy sources, rather that they are fossil fuel waste products.

There may be scope for units on industrial estates or other groups of large heat

users to develop small district heating networks as a preliminary step to extension

into the community. Planning departments could encourage this movement by

avoiding piecemeal development of single dwellings, and supporting applications for

multiple housing units with their own shared heat generation facilities powered by

renewable energy.

Smaller, more widely dispersed communities, such as Stromness, will find that the

achievement of renewable heat targets is more likely to be met by individual

responses: firstly by reducing demand through insulation, and then by installation of

biomass boilers, heat pumps, and solar thermal hot water systems. Continued

support through grants and incentives will be required until such time as the cost of

fossil fuel exceeds that of the renewable alternative.

The research and calculations undertaken during this thesis reaffirms the author’s

view that fossil fuels are too valuable to be burnt – their unique chemical properties

are essential to our future – and that we are surrounded by many different energy

sources if only we but look and think. Coastal communities have advantages over

densely populated conurbations, as have villages in forests or cities in north Africa.

Each must find and develop energy solutions best suited to their environment.

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Available at: http://www.pbase.com/mpwheatley/image/17854604 Accessed on 6th August 2009.

Winter, F. E. (2004). Studies in Hellenistic Architecture. Available at:

http://books.google.co.uk/books?id=03UNLhtEP1oC&lpg=PP1&dq=studies%20in%20hellenistic

%20architecture&pg=PP1#v=onepage&q=&f=false Accessed on 6th August 2009.

BIBLIOGRAPHY

E & Cyril Swett. (2009). Putting a Price on Sustainability. Building Research Establishment

(BRE). Watford.

Department for Communities and Local Government. (2009). Code for Sustainable Homes.

Case Studies. Department for Communities and Local Government. London.

IMechE. (1999). Recent Developments in Refrigeration and Heat Pump Technologies.

Professional Engineering Publishing Ltd. London.

APPENDICES


Appendix 1 – Scottish Heat Map

The Scottish Heat Map project was undertaken by AEA Energy & Environment

on behalf of the Forum for Renewable Energy Development in Scotland

(FREDS) in 2007 with support from the Energy Saving Trust. Compiled from a

number of data layers using GIS, a software package for modelling

geographical information, a Heat Map for Scotland was produced. From this,

coastal communities with significant heat requirements can be identified.

Author’s note: the legend has been enlarged from original to improve legibility.

APPENDICES


Appendix 2 – Survey Schedule and Questionnaires

Survey area and questionnaire delivery schedule

Date Location References

Wednesday 17th June 2009 Coplands Drive, Coplands Road 1-16

Thursday 18th June 2009 Hamnavoe 17-89

Friday 19th June 2009 Hillside Road 90-160

(Hillside Park from 122 to 140)

Monday 22nd June 2009 North End (north from Co-op), 161-200

Cairston Road (to Garson Drive)

Tuesday 23rd June 2009 Garson Loan, Cairston Drive 201-217

remainder of Cairston Road

Academy, Business Park B4-B5

Wednesday 24th June 2009 Stromness Hotel, from Pier 218-249

Head - Ferry Road to Co-op, inc

John Street and North End (east side),

and North End (west) from Northvet to Co-op

Tod’s of Orkney B6

APPENDICES


Example questionnaire – domestic

APPENDICES


Example questionnaire – industrial

APPENDICES


Appendix 3 – Key District Heating Schemes in UK

continued on next page

APPENDICES


APPENDICES


Appendix 4 – Insulation material

Farm diversification –

a business opportunity?

In Orkney, and other remote areas of Scotland, one factor raised as a deterrent

to home insulation is the bulkiness of insulation products and costs of

transporting them from manufacturing locations.

The question arose as to whether there was potential for manufacturing

insulation locally.

On investigation, the National Farmers’ Union confirm there are 60-70,000

sheep in Orkney, while Thermafleece advise that 25 fleeces are required to

produce 10m2 of 100mm thick insulation.

Assuming an average loft area of 100m2 the annual clip in Orkney might provide

sufficient loft insulation for approx 1,000 houses: further research is required

into the economic feasibility of such a project.

At £3-4 per fleece, however, the cost of natural sheepswool insulation is higher

by a factor of 4 than those products using glassfibre.

Borax is commonly used as a fire retardent in natural insulation. An alternative

solution could be whey (a waste product from Orkney Cheese), which releases

nitrogen when heated and is used to treat wood shavings insulation in kit

houses built by Baufritz in Germany.

APPENDICES


Appendix 5 – Wind Chill Factor

The Northern & Western Isles Energy Efficiency Centre, Kirkwall, Orkney


PLAGIARISM STATEMENT

INSTITUTE OF PETROLEUM ENGINEERING

MSc Renewable Energy Development

2008 / 2009

Project Title:

RENEWABLE HEAT IN COASTAL COMMUNITIES:

DISTRICT HEATING CASE STUDY

I, Linda Craig Forbes, confirm that this work submitted for assessment is my

own and is expressed in my own words. Any uses made within it of works of

other authors in any form (ideas, equations, figures, text, tables, programmes

etc) are properly acknowledged at the point of their use. A full list of the

references employed is included.

Signed: ............................................................

Date: ..............................................................