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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

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
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
possible right or helpful questions my translation of sources
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?
slide4

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

setting up the problem 1
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
setting up the problem 2
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

slide7

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
slide8

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

slide9

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

slide10

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

slide11

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

slide12

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

forestry research questions for the u s on wood energy carbon offsets
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)
slide14

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

slide15

Thank you

Ken Skog – kskog@fs.fed.us

slide16

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