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

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? Bioenergy system Fossil fuel 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) = [E FF (t) – NE w (t)] / E FF (t) E FF (t) = Cumulative fossil fuel emissions avoided NE w (t) = Cumulative wood emissions to time t – Change in forest growth/ emissions due wood energy use to time t CN(t) 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 1. Additional harvest from a managed forest 2. Logging residues from a managed forest 3. New plantations on fallow land 4. New plantation after harvesting existing forest

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

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 Source: G. Zanchi 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

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

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. CO 2 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