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Wood Bioenergy Carbon Accounting – Beyond Carbon Neutrality

Wood Bioenergy Carbon Accounting – Beyond Carbon Neutrality 2011 National FIA User Group Meeting Sacramento, CA March 8-10, 2011 Ken Skog, Project Leader USDA Forest Service Forest Products Laboratory Madison, Wisconsin Topics

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Wood Bioenergy Carbon Accounting – Beyond Carbon Neutrality

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  1. Wood Bioenergy Carbon Accounting – Beyond Carbon Neutrality 2011 National FIA User Group Meeting Sacramento, CA March 8-10, 2011 Ken Skog, Project Leader USDA Forest Service Forest Products Laboratory Madison, Wisconsin

  2. Topics • What are the “right” or “helpful” research questions to ask about wood bioenergy carbon emission offsets? • A Joanneum Research study – GHG offsets by wood source over time • Carbon neutrality number over time – CN(t) • Logging residue [temperate forests] • Intensified thinnings [Austria] • Intensively managed forest plantations • on fallow ag land • by clearing existing forest (if time) • More forestry research questions

  3. Possible “right” or “helpful” questions (my translation of sources) • Searchinger et al. – to what degree does an increase wood energy use decrease GHG emissions [over time] by alteration of forest growth/ emissions. • 6/18/2010 letter from Forestry groups to EPA Administrator – Is an increase in wood energy use “good” as long as forests are managed sustainably and forest carbon is increasing? (letter says yes) Good? = less carbon emissions “overall” to the atmosphere? • Manomet study – How quickly (years) and by how much will emissions from fossil fuel power system be offset by increasing use of Mass. forest biomass in selected wood-power systems? • Joannuem Research – By increasing use of a specific source of wood fuel use in place of fossil fuel for power, what fraction of a fossil systems emissions would be offset by using specific wood sources in t years?

  4. Question: By increasing use of a specific source of wood fuel use in place of fossil fuel for power, what fraction of a fossil power emissions would be offset by using specific wood sources in t years? Fossil fuel system Bioenergy system Source: Giuliana Zanchi

  5. Setting up the problem - 1 • Focus: • What is the emission offset of an increase in wood use ( to a new constant level) to make electric power/ heat and power • Assume • kwh / kg wood carbon = kwh / kg of coal carbon • Kwh / kg natural gas carbon = 0.6 kwh / kg wood carbon • Exclude emissions to obtain and transport wood or fossil fuel

  6. Setting up the problem - 2 • Compute carbon neutrality number, CN(t) • Fraction of fossil emissions offset by time t by increase in wood use from a given source CN (t) = [EFF(t) – NEw(t)] / EFF(t) EFF(t) = Cumulative fossil fuel emissions avoided NEw(t) = Cumulative wood emissions to time t – Change in forest growth/ emissions due wood energy use to time t CN(t) < 1 cumulative net wood emissions > than fossil emissions CN(t) = 0 cumulative net wood emissions = fossil emissions CN(t) = 1 net wood carbon storage totally offsets fossil emissions

  7. Examples: CN(t) for wood use from • Additional harvest from a managed forest • Logging residues from a managed forest • New plantations on fallow land • New plantation after harvesting existing forest

  8. Illustrative case studies • Model: GORCAM (Graz Oak Ridge Carbon Accounting Model) • Growth curve based on Austrian yield table for Spruce • No disturbances included • Biomass net emissions (green) • Fossil fuel emissions (orange) • CN factor (black) Source: G. Zanchi

  9. 1. Additional fellings from a managed forest (1) Rotation period: 90 years Rotation forest: 90 hectares Harvesting: a) Baseline: 60% of increment b) New Management: 80% of increment The additional biomass is used for bioenergy Source: G. Zanchi

  10. 1. Additional fellings from a managed forest (2) Rotation period: 90 years Rotation forest: 90 hectares Harvesting: a) Baseline: 60% of increment b) New Management: 80% of increment The additional biomass is used for bioenergy • Biomass net emissions (green) • Fossil fuel emissions (orange) • CN factor (black) • CN(t) = 0 at ~ t = 180 yrs • CN(400) = ~ 0.5 Source: G. Zanchi

  11. 2. Felling residues from a managed forest • Rotation period: 90 years (90 ha) • Baseline: Logging residue left in the forest • New Management: 2/3 logging residue to bioenergy • Biomass net emissions (green) • Fossil fuel emissions (orange) • CN factor (black) • For a coal alternative • CN(30) = 0.6 • If natural gas is the alternative • CN(30 ) = 0.3 Source: G. Zanchi

  12. 3. New plantations • Baseline: low carbon change land (e.g. cropland) • New Management: new forest to produce bioenergy (no forest land use change) • Biomass net emissions (green) • Fossil fuel emissions (orange) • CN factor (black) • CN(t) >1 for all t Source: G. Zanchi

  13. Forestry research questions for the U.S. on wood energy carbon offsets • For logging residue – what is CN(t) by location? (generate U.S. map using logging residue decay curves) • Are there better metrics of emission offset over time ? (e.g. relative cumulative radiative forcing – wood vs fossil fuel) • CN(t) for current timber management with more thinnings, by forest type • CN(t) for fire hazard reduction thinnings? • CN(t) for mill residue (is landfill the alternate decay if not used? Composite products? pulp?) • Are there broad management guidelines for thinnings to attain say CN(100) > 0.5? (e.g. Marland and Marland 1992)

  14. Publications Manomet study: Walker, T. (Ed.). Contributors: Cardellichio, P., Colnes, A., Gunn, J., Kittler, B., Perschel, R., Recchia, C., Saah, D., and Walker, T. 2010. Biomass Sustainability and Carbon Policy Study: Report to the Commonwealth of Massachusetts Department of Energy Resources. Manomet Center for Conservation Sciences. Report No.: NCI-2010-03. Repo A., Tuomi M., Liski J., 2010. Indirect carbon dioxide emissions from producing bioenergy from forest harvest residues. GCB Bioenergy, no. doi: 10.1111/j.1757-1707.2010.01065.x McKechnie J., Colombo S., Cheng J., Mabee W., MacLean H.L. Forest bioenergy or forest carbon? Assessing trade-offs in greenhouse gas mitigation with wood-based fuels. Environ Sci Technol. 2011 Jan 15;45(2):789-95 Palosuo T, Wihersaaari M, Liski J, 2001. Net Greenhouse Gas Emissions due to energy use of forest residues –Impacts of soil carbon balance. Woody biomass as an energy source – Challenges in Europe. EFI proceedings no 39, 2001 Schlamadinger B and Spitzer J, 1994. CO2 mitigation through bioenergy from forestry substituting fossil energy. In: Biomass for energy, environment, agriculture and industry. Proceedings of the 8th European Biomass Conference.Vienna, Austria, 3-5 October 1994, Volume 1. Ed. Chartier P., Beenackers A.A.C.M., Grassi G., pp. 310-321. Schlamadinger B, Spitzer J, Kohlmaier GH, Lüdeke M, 1995. Carbon balance of bioenergy from logging residues. Bioamss and Bioenery 8 (4): 221-234. Schlamadinger B and Marland G, 1996. The role of forest and bioenergy strategies in the global carbon cycle. Biomass and Bioenergy 10 (5/6): 275-300. Source: G. Zanchi

  15. Thank you Ken Skog – kskog@fs.fed.us

  16. 4. New plantations – existing forest is converted • Baseline: Existing forest is converted • New Management: new forest to produce bioenergy • Biomass net emissions (green) • Fossil fuel emissions (orange) • CN factor (red) • CN(t) < 0 for t < ~80 years Source: G. Zanchi

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