T SEC-BIOSYS: A whole systems approach to bioenergy demand and supply www.tsec-biosys.ac.uk Carly Whittaker Imperial Co

1. TSEC-BIOSYS: A whole systems approach to bioenergy demand and supply www.tsec-biosys.ac.uk Carly Whittaker Imperial College/North Energy Associates carly.whittaker@northenergy.co.uk Biomass role in the UK energy futures The Royal Society, London: 28th & 29th July 2009 1

2. Topic 3.2. Full supply chain greenhouse gas (GHG) emissions assessment Carly Whittaker Dr Richard Murphy Dr Nigel Mortimer Topic 2.3 – Pre-harvest GHG balance of energy crops Dr Jon Hiller Prof. Pete Smith

3. Aims of work • Review and integrate relevant studies on carbon balances of bioenergy supply chains Life Cycle Analysis approach • Produce coherent model applicable to the UK bioenergy sector Sector not yet fully developed…Examine biomass projects in operation now Produce flexible model • Assess carbon abatement ‘wedges’ for the UK Depends on supply and end-use. Produce series of multipliers (e.g Kg CO2/MWh or /ODT)

4. Case Studies: Supply Chains Consumers: • Co-firing – Drax • Dedicated electricity – Wilton 10 • District heating – Barnsley • CHP – plan b: Literature Suppliers: • Miscanthus –Bical • SRC–Renewable Energy Growers • Forest Residues – Forestry Commission

5. Kg CO2 eq. tonnes MWh e/t MJ Grid Electricity MJ Diesel Kg CO2eq Kg CO2 eq. Machines On-site Processing MJ Natural Gas Kg CO2 eq. LCA: Systems Boundaries of Model Kg CO2 eq. Biomass feedstock production MJ Diesel Conversion to energy Processing Transport Storage Machines Construction Vehicles Fertilizers Stuff Construction Material Losses Material Losses Material Losses • Overall GHG savings depends on overall GHG of biomass supply chain • Define relevant supply chain stages • Significant data collection required to quantify: • Direct & Indirect energy consumption/emissions: • Fossil fuels • Manufacture of consumed materials • Construction of machines/buildings/vehicles

6. TSEC-LCA-Model Fully transparent model- (MS Excel) - Can be replicated or updated with improvements in knowledge • Covers : • 15 Types biomass • 3 Land-use reference systems • 3 Waste reference systems • 10 Transport options • Outputs: • ‘To the farm gate’ – per tonne @ m.c • ‘To factory/power station gate’- per tonne processed • End use: Electricity, heat, CHP, or co-fired electricity Output: Energy requirement and GHG emissions profile specific to your supply chain Breakdown of where all emissions occur

7. Output: Energy requirement and GHG emissions profile specific to your supply chain Breakdown of where all emissions occur

8. Elements of the Tool • 1. Biomass Feedstocks: • MJ/Kg CO2 eq. per ODT of: • Miscanthus • Wheat Straw • Forest Residues • Short Rotation Coppice • Waste Wood • Arboricultural Arisings • Olive Residues/Peanut Shells/generic waste • Sunflower Husk Pellets • Dried DDGS • Dried Rape Meal • Stemtips & Branches • Sawdust • Slabwood • Whole Tree Thinnings • Roundwood Pellets 11 Tree Species 4-6 Yield Class Ranges 28 Regions UK (road construction intensity

9. Elements of the Tool • 3 Types of Biomass • Miscanthus • Wheat Straw • Forest Residues • Short Rotation Coppice • Waste Wood • Arboricultural Arisings • Olive Residues/Peanut Shells/generic waste • Sunflower Husk Pellets • Dried DDGS • Dried Rape Meal Energy Crops LAND Co-products Waste Each treated in a different way in LCA With different LCA issues

10. Energy Crops LAND Co-products Waste • Site inputs & operations • Yield over rotation • Moisture content • Land-use reference system • Carbon sequestration -Allocation procedure • No value to anyone anywhere • Would have been disposed • Reference system? Each treated in a different way in LCA With different LCA issues

11. Site inputs & operations Nothing Artificial NPK Slurry PK Slurry • Diesel fuel (site establishment and harvesting) most significant sources of emissions - constant • Artificial fertilizers increase overall emissions • N=N2O emissions • Slurry energy requirements transport could be cancelled out

12. Yield over rotation • Increase in yield lowers emissions per ODT from shared events • Harvesting requirements constant • Not enough known about yield responses to fertilizer

13. OSR GHG cost SRC Miscanthus arable arable grassland woodland GHG benefit - Land-use change and Carbon sequestration • Soil emissions/sequestration depend on • Previous land use & proposed new land use St. Claire et al., 2008 1) Don’t replace woodlands with any energy crop 2) Also, don’t replace grasslands with OSR 3) SRC & Miscanthus on grassland and arable okay 4) OSR on arable food crop land ~neutral

14. - Land-use change and Carbon sequestration • SRC and Miscanthus generally have better soil C balance than WW or OSR (i.e. they have lower net emissions or higher net sequestration) • Soil GHG emissions are highest in regions where Soil C is currently highest, e.g. Westerly regions, the fens. • So net balance clearly depends both on the bioenergy crop cultivated, and on the initial soil conditions

15. - Land-use change and Carbon sequestration • (Average) equilibrium soil C of • SRC ~110 t/ha • Miscanthus ~100 t/ha • WW, ~45 t/ha • OSR, ~55 t/ha Growing Miscanthus and SRC on arable and grassland leads to GHG saving rather than loss (up to~4-5 CO2 equiv t/ha/year)

16. - Land-use change and Carbon sequestration Hillier et al., … GHG cost GHG benefit

17. Co-Products

18. Allocation • Splitting site emissions between products • Only a real issue when fertilizer inputs are high E.g. Wheat Straw

19. Allocation E.g. Straw Bales Economic Energy Mass LCA’s that have adopted different allocation procedures cannot be directlycompared

20. Wastes

21. SOURCE SINK • Waste Wood • Arboricultural Arisings Waste • No value to anyone anywhere • Would have been disposed • Collection • Reference system? Landfill DEFRA WRATE Damen & Faaij,2003 IPCC default Mann & Spath,2001 Net sink or source? Highly sensitive to degradation rate Gardner et al., 2002

22. …Kg CO2 eq. ‘per ODT biomass’ • Can depend on many factors • Quantifiable things • Inputs • Yield • Moisture Content • Material losses • Methodology Decisions: • Land use change • Landfill behaviour TSEC LCA Model is flexible

23. Transport Volume-based t-km emissions - Volume database - Bulk density database • Transport Emissions for • - Road • - Rail • - Marine transport Electricity consumption during processing

24. GHG Benefit of Pellets vs. chips? Biomass heat 1268 km 130 km

25. Overall Emissions Per MWh • Per MWh • Biomass production phase is where most emissions occur • Compared to: • - Transport (5-10 Kg CO2/MWh) • Power station construction (15 kg CO2 eq./MWh) • Non-CO2 emissions (15 kg CO2 eq./MWh)

26. Overall Emissions • Biomass- electricity can offer significant savings • Best generated as part of a CHP system • Co-fired electricity is low but still burns coal E.g. SRC chips 40% 80 Kg CO2 eq./MWh 40% 160 Kg CO2 eq./MWh • Heat is ‘best’ use for biomass • High conversion efficiency • Lower overall emissions per MWh 90% 50% 90% 75% 30% 20% 40% Per MWh

27. Emission Savings • Overall GHG savings depend on GHG balance of biomass supply chain - Significant data collection required • LCA’s should be provided in fully transparent manor • Replicable and updatable • Significant savings can be made with biomass • Key sensitivities are to crop yield, fertiliser usage and land use change • Allocation procedure can vary results- mainly important for high input crops (e.g. wheat) • Actual emission savings depend on what you are displacing • Heat production provides lowest emissions per MWh and has best conversion efficiency • Significant greenhouse gas savings can be made with dedicated electricity generation • Co-firing can also save emissions- but requires large quantities of biomass • Carbon Sink or Sinner? • Depends on previous land use • Overall carbon sequestration with energy crops replacing arable and grassland

28. Report produced August 09

29. Thank you for your attention! www.tsec-biosys.ac.uk 29