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Life Cycle Assessment of Energy Use and Air Emissions from Producing Electricity from California Forest Wildfire Fuels Treatments: Phase 1 Results
Joyce Cooper,* University of Washington
Mark Nechodom, Pacific Southwest Research Station, USDA Forest Service
Laurie Perrot, Pacific Southwest Research Station, USDA Forest ServiceUnder contract with California Energy Commission, the USDA Forest Service has been working to identify and analyze social, economic, and environmental costs and benefits of using biomass removed during forest wildfire treatment (forest thinning to promote healthy burn patterns as opposed to wildfires) to generate electrical power for specific sites throughout California. Phase 1 of this project offers only a portion of the full assessment, intended to provide proof-of-concept for the connection of 8 models: (1) a Stewardship and Fireshed Assessment, (2) a characterization of forest operations and equipment configurations, (3) a vegetation dynamics assessment, (4) an assessment of fire behavior, (5) a power plant analysis, (6) a characterization of landscape and habitat response, (7) an analysis of treatment costs and benefits, and (8) an LCA.
The Phase 1 LCA quantified life cycle energy use (total, fossil, and petroleum), PM10 emission, and the contribution to climate change (from CO2, N2O, CH4), acidification (from SOx, NOx), and photochemical smog (from CH4, NOx, CO, NMVOCs) for the acquisition and processing of residual biomass (harvest, chipping operations, and underburning within the forest), transport of chips to a biomass power plant, the conversion of the chips into electricity, and wildfires for a 2.7 million-acre landscape encompassing both public lands (portions of the Plumas, Lassen, and Tahoe National Forests and Lassen National Park) and private lands surrounding the Mt. Lassen power plant in Westwood, California. Three treatment scenarios were investigated: (1) no-treatment, (2) treatment of Industrial Private Forests only, and (3) treatment of Industrial Private and Public Multiple Use Forests. Life cycle emissions estimation primarily relied on the suite of project models, the USEPA’s NONROAD and MOBILE models, the USDOE’s GREET model, and the USPEA’s TRACI. Also, climate change impacts are presented within the context of the IPCC model for forest carbon flows and all impacts were normalized using California estimates of energy use and emissions.
The project experience revealed that (1) It is possible to construct a set of interconnected forest operations and equipment characterization, fire behavior assessment, and the power plant analysis models in support of LCA; (2) Data and models are available to represent the life cycle of a range of technologies for developing U.S. forest bioproduct systems; and (3) Presentation of results in gross and followed by a variety of computational interpretations provide insights for decision making and a starting place for future assessments. Specific results concerning the treatment scenarios evaluated revealed (1) Whereas the biomass power plant efficiency is critical to the overall energy balance, the consumption of fossil and petroleum fuels during harvest, chip transport, or power plant operation play a less important role; (2) Forest processes related to photosynthesis, plant respiration, decomposition of litter and soils, despite the uncertainty in estimates, are the most important to understanding long-term carbon storage; (3) If trying to optimize the treatment system, the carbon embodied in what is removed from the forest and the power plant efficiency are important; (4) Wildfires, the biomass power plant, and the conventional electricity generation methods are all important to the contribution to acidification; and (5) treatment systems that maximize wildfire reductions will minimize the life cycle contribution to smog formation and PM10 emissions.
* corresponding author: cooperjs@u.washington.edu