Life cycle GHG emissions of biofuels: Results from review of studies

Emanuela Menichetti

UNEP-DTIE, Energy Branch

European Environment Agency Expert workshop

Copenhagen, 10 June 2008

Bioenergy Strategy developed in 2007

UN Energy report on Bioenergy

Most relevant current activities

GBEP => UNEP entrusted with developing sustainability work stream

RSB => UNEP is a Steering Board Member and participates in all 4

technical working groups

Jatropha Roundtable => network of centres of excellence to share

information on agronomics, sustainability criteria, technologies and

business models

UNEP’s Activities on Bioenergy

Two main review studies

Chapter on LCA for the OECD MCM report in cooperation

with the IEA

Report for the International Panel for Sustainable

Resource Management

Life cycle GHG emissions of biofuels

Overview

Review and analysis of 60 studies Full LCA studies: 32% Energy and GHG emission balances: 33% Methodological / review studies: 23% Life cycle inventories: 7% Energy balances: 5%

Focus mostly on transport applications

Selected results for GHG (w/o LUC)

Key determinants of results (w/o LUC)

Two main life cycle stages – and within these two – a limited number of variables are responsible for the largest impact share

Agricultural phase

N2O balance

Assumptions on co-products (and allocation)

Transformation phase

Process energy

Assumptions on co-products (and allocation)

Example: rapeseed biodiesel

Agricultural phase Conversion phase

Land use reference scenario

Crop yield Amount of fertilizers

N balance Allocation Energy fuel used

Co-products allocation

Green: quite consistent background assumptions

Orange: some discrepancies observed, it affects results to some extent

Red: high inconsistency area, it affects results significantly

N2O emissions

Ecobilan

(2002)

EMPA

(2007)

IPCC default value

Emission factor (N2O) 0.5% 1.6-3.5% 1%

Ecobilan

(2002)

EMPA

(2007)

Mass allocation (46% to RME)

Economic allocation

(87% to RME)

Overall GHG improvement on biodiesel : Ecobilan 80% vs. EMPA 23%-41%

Allocation methods

QUESTIONS: What is the most appropriate allocation method for biofuel co-products for

regulation purposes? One method for whole life cycle or mixed approach? Consistency with allocation method(s) in fossil fuel chains?

Sub-division

System expansion

Allocation based on physical criteria

Allocation based on

other criteria

Mixed methods

No allocation

to co-products

Not applicable /

Not available

Mass-based

allocation

Energy content-based

allocation

Economic allocation

1 21 2 3 7 8 1 17

Influence of process energy

QUESTION: What should be used for regulation purposes? Present average mix, state-of-the art, BAT, expected trends?

Quantity and type of energy source significantly affect LCA results

State-of-the art vs. old plants (e.g. Wang et al. 2007)

Wide range of specific process energy consumption observed in reviewed studies (e.g. Unnasch and Pont, 2007)

Other methodological aspects

Various (and non harmonised) LCI databases

Various LCIA methods used

Most studies only cover CO2, N2O and CH4

Various reference scenarios modelled

Uncertainty related to the fossil fuel chain: Variability in assumptions and results of fossil fuel chains

Lack of updated LCA of marginal fossil fuel production (deep

extraction, unconventional oils)

Comparison with average or marginal fossil fuels?

Land use change

Very significant impacts on overall GHG balances Direct land use change can be integrated in LCA

Harmonization on data and methods needed

More research needed to include indirect land use change What is the reference baseline? How to take productivity and process improvements into account?

tC/ha Arable land

Cultivated land

Permanent grassland

Grassland Lightly forested

area

Tropical rain forest (min. soil)

Savannah Oil palm plantation

EC RES directive 82 181 181 189

German SBO draft 55 70 265 134 110

Conclusions

Research gaps Need for more full LCA studies on other crops and geographical contexts

Number of open questions N2O emission factors Allocation methods Consistency of fossil fuel chain LCA Level of technology representativeness for policy-making decisions Direct and indirect land use change

Parametric LCA? To better evaluate the influence of assumptions To depict future improvements To orientate policy making

Harmonisation of rules GBEP, RSB, UNEP LCI, EPLCA Look at experience in the eco-labelling sector (PCR-like process)

Division of Technology, Industry and EconomicsDivision of Technology, Industry and EconomicsEnergy BranchEnergy Branch

15 rue de Milan, 75009 Paris15 rue de Milan, 75009 ParisFranceFrance

tel. : +33.1.44.37.30.07tel. : +33.1.44.37.30.07

fax. : fax. : +33.1.44.37.14. 74+33.1.44.37.14. 74e-mail: emanuela.menichetti@unep.fre-mail: emanuela.menichetti@unep.fr

www.uneptie.fr/energywww.uneptie.fr/energy

Division of Technology, Industry and EconomicsDivision of Technology, Industry and EconomicsEnergy BranchEnergy Branch

15 rue de Milan, 75009 Paris15 rue de Milan, 75009 ParisFranceFrance

tel. : +33.1.44.37.30.07tel. : +33.1.44.37.30.07

fax. : fax. : +33.1.44.37.14. 74+33.1.44.37.14. 74e-mail: emanuela.menichetti@unep.fre-mail: emanuela.menichetti@unep.fr

www.uneptie.fr/energywww.uneptie.fr/energy