The Importance of tracking combined land carbon change effects of increased wood and ag biomass energy demand

Transcription

1 The Importance of tracking combined land carbon change effects of increased wood and ag biomass energy demand IEA Bioenergy Task 38 Argonne National Laboratory April 12-13, 2012 Ken Skog USDA Forest Service Forest Products Lab Madison, WI Eric M. White Oregon State University Corvallis, OR Collaborators Greg Latta and Darius Adams, Oregon State University Ralph Alig, PNW Research Station, USDA Forest Service Bruce McCarl, Texas A&M University Justin Baker and Brian Murray, Duke University Steve Rose, Electric Power Research Institute Robert Beach, RTI Environmental Protection Agency USDA Forest Service Economic Research Service 1

2 Main points Given large scale bioenergy demands and multiple wood and ag biomass sources Given shifts in biomass sources over time, e.g. from forest biomass to herbaceous crops It may not be accurate to account separately over time for carbon recovery for wood and ag biomass sources Tracking of forest sources alone can show large carbon losses Tracking of forest + ag together shows large carbon recovery U.S. Energy projections 3 bioelectric power scenarios Baseline Reference case from 2010 U.S. Annual Energy Outlook (AEO) projection Two cases for Renewable Energy standards RES10 = 10% of electric power from renewables by 2020 RES20 = 20% of electric power from renewables by 2020 After 2030 bioelectricity production is held constant 2

3 FASOM-GHG Linked model of U.S. agriculture and forest sectors 80 year projections Dynamic optimization to simulate markets (max PNV consumer plus producer surplus gives optimal investments) Regionally-explicit, we report national results Includes a bioenergy sector (bioelectricity, biofuels) Includes GHG accounting land carbon, HWP carbon, mgt emissions (e.g. harvest equipment) Bioelectricity Feedstocks Agriculture crop residues Agriculture energy crops Short-rotation woody crops Logging residues Milling residues and pulpwood 3

4 Bioelectricity Production Direct firing 100 MW Co-firing (with coal) Greenhouse Gas Accounting Land-based GHG accounting in forest and agriculture sectors from Carbon in forest and agriculture biomass and soils Carbon change due to movement of land (afforestation/deforestation) between agriculture and forest Emissions from forest and agriculture production activities (very small) Emissions from livestock (little chg in our cases) Carbon in Wood products (little chg in our cases) 4

5 Bioelectricity Production Quadrillion BTUs RES 10, Change from Base Agriculture Sector Forest Sector Quadrillion BTUs RES 20, Change from Base Agriculture Sector Forest Sector 300 Cumulative extra biomass emissions 250 M Tonnes CO2e RES 20 RES 10 Forest biomass M Tonnes CO2e 5,000 4,500 4,000 3,500 3,000 2,500 2,000 1,500 1, RES 20 RES 10 Forest + ag biomass 5

6 Forest Sector Land Change RES 10 scenario, small increases in afforestation and deforestation RES 20 scenario, decline in afforestation and large increase in land to agriculture Forest Area Under RES20 large conversion to agriculture, reduced afforestation 6

7 Carbon neutrality number for increase in cumulative forest + ag biomass for electric power RES 10 RES Carbon neutrality number for cumulative increase in forest biomass for electric power CN(t) = Fraction of emissions offset by land carbon change by time t RES 10 RES 20 Conclusions Where forests and agriculture can both supply biomass AND land use can change Forest carbon recovery from forest biomass burning can be very poor when there is conversion to ag land However considering ALL forest + ag biomass burning and forest + ag land carbon Forest + Ag land carbon recovery can be very rapid 7

8 Implications for LCAs for bioenergy General demand for biomass for energy can result in shifts of land from ag to forestry or forestry to ag. To determine the carbon impact of increased biomass use on land carbon will require either 1) Modeling of scenarios that allow a) for mixed ag and forest supply and b) land use change or 2) Explicit assumptions about sources of supply and extent of land use change 8