harvest residue utilization in small- and large-scale bioenergy Systems:

1. harvest residue utilization in small- and large-scale bioenergy Systems: Life cycle results and the effects of common errors in the application of LCA methods Julian Cleary, Post-Doctoral Fellow Faculty of Forestry University of Toronto

2. Bioenergy background Bioenergy is currently the world’s largest renewable energy source and supplies 10% of primary energy demand. World Primary Energy Demand 2010 (IEA)

3. Increasing the Supply… Moving beyond pulp and paper sector to modified coal plants and CHP systems The Potential Problems… Costs and environmental impacts

4. Next Step Undertake research LCA of forest bioenergy systems of different scales Cogeneration vs. electricity-only systems

5. Here are the things we “know”… Smaller scale plants cost more (relative to potential electricity output) Larger scale plants are more efficient Average biomass shipping distances are longer for large-scale plants Adequate nearby heat demand is less likely next to large-scale plants Wood pellets require more processing than wood chips but are more efficient to store due to their higher bulk density

6. Problems with what has been done? Common methodological errors boost estimated benefits Numerous bioenergy LCAs address GHG mitigation 1) Assumption of carbon neutrality 2) Omission of climate effect of GHG emission timing on overall mitigation 3) The displaced and consumed electricity are not identical To what extent have these errors affected GHG mitigation estimates?

7. LCA Assumptions Assumed 20 year project lifespan US EPA’s TRACI 2.1 LCIA method with Canada 2005 normalization Financing – 8% int. rate US EI database, with LCA unit processes adapted to the conditions modelled Time-adjusted GHG emissions

9. Presumed source of biomass: Haliburton Forest Annual harvest of approx. 35,400 green tonnes Significant amounts of residue left after harvest Approx. 7,850 dry tonnes Based upon estimates by Rudz

10. Haliburton harvest residue can supply the electricity needs of almost 200 Ontario homes Biomass Collection Reducing the topping diameter of the cut by 5.4 cm will result in an additional 1,183 dry tonnes collected Biomass collected on 2/3 of harvest area Cost: $16.22 per dry tonne http://www.pfla.bc.ca/wp-content/uploads/2012/07/harvest-residue.jpg

11. Mill/gasifier: 27 km Use of self-loading truck High fuel use on unpaved roads, idled trucks, lower truck capacity for residue Atikokan: approx. 1900 km Transportation of feedstock • Average distance from harvest sites to: Residue Shipping Cost: $21.08/dt Pellet Shipping Cost: $49.77/dt

12. Harvest residue processing Drying, chipping and/or pelletization Small-scale CHP system: -drying uses recovered heat More equipment and electricity used in pelletization Large-scale combustion system: -hog fuel burned for drying -equal to 15% of harvest residue inputs S1 Cost: $9.15 per dry tonne S2 Cost: $51.72 per dry tonne

13. Wood Chip Gasification Hypothetical 250 KWe gasifier Producer gas combustion in producer gas engine -Electrical efficiency: 40% 39% of the energy content of the wood is lost in the conversion to producer gas Overall electrical efficiency -24%

14. Heat from Gasification 32% of recovered heat is used for gasification reaction and wood chip drying Available heat can dry fourteen times the Haliburton kiln capacity

15. Modifications to Atikokan Generating Station $170 million (capital) Electrical efficiency -31.6% (excluding input fuel loss during drying and pelletization) -8% capacity factor http://www.opg.com/power/thermal/atikokanfactsheet1009.pdf

16. Contribution of each stage of the S1 and S2 life cycles to non-biogenic Greenhouse Gas emissions If displacing coal, S1 emissions rise to 46 g, and S2 emissions rise to 193 g.

17. Time–Adjusted Cumulative GHG Mitigation

18. Non-Time-Adjusted GHG Mitigation

19. Timing of Emissions Emissions do not all take place at the beginning of the selected time horizon Time-adjusted GHG mitigation is at a far lower magnitude (omitting time-adjustment boosts GHG mitigation by 51% over 50 yrs). This change in GHG modelling does not alter the position of S1 relative to S2 in terms of GHG mitigation.

20. Carbon Neutrality Incorrect assumption of C neutrality boosts GHG mitigation estimate by over 50% over a 50 year time horizon

21. Other findings The average area subject to residue removal was 3.7 m2/kWh The small-scale system has a far greater potential to reduce impacts than is indicated in the results because 63% of the potentially recoverable heat remains unused

22. Average annual costs per kWh generated over the 20 year lifespan of each project (in 2010 dollars)

23. Key Findings Electrical efficiency disadvantage of small-scale CHP system can be overcome even at low levels of heat recovery S1, but not S2, can surpass even the non-biogenic GHG benefits from renewable electricity generation alternatives C storage effect delays GHG mitigation by approximately 4 years The avoided propane use in the lumber kiln compensates for all of the non-biogenic GHGs of the small-scale CHP system.

24. Future Research Trajectories Biochar and bio-oil

25. Thank you! Ontario Power Generation Haliburton Forest and Wildlife Reserve NSERC MITACS-Accelerate

26. Harvest Residue Vs. Dedicated Harvest • Unlike fossil fuels, harvest residue decomposes if left in place • Unlike a dedicated harvest, residue collection does not affect carbon sequestration from trees