February 17, 2006 | General

Biomass Inventory And Bioenergy Assessment

BioCycle February 2006, Vol. 47, No. 2, p. 49
Washington study shows that the state produces over 16.9 million tons of underutilized biomass that can generate over 15.5 billion kWh of electrical energy.
Craig Frear and Mark Fuchs

A biomass inventory and bioenergy assessment for Washington State was completed, producing a final report as well as a web accessible computer database complete with GIS maps on a Visual Basic platform (http://www.pacificbiomass.org). The goal of the study was to inventory Washington’s bioresources as a first essential step for all related planning efforts to implement the state Beyond Waste strategy for reduction of organic residuals in solid waste. This inventory also represents a first step toward a sustainable energy policy and vision within the state since information on type and geographic distribution of biomass was perceived as critical for feasibility analysis and project prioritization.
This project geographically identified, categorized, and mapped 45 potential sources in Washington at a county level. The categories included field residues, animal manures, forestry residues, food packing/processing waste, and municipal wastes. The biomass inventory was then converted to potential energy production using anaerobic digestion and simple combustion as representative conversion technologies. A five-step method was used for inventorying and determining the biomass and potential electrical energy from Washington’s biomass. First, agriculture, processing and municipal statistics and databases along with personal interviews with agriculture and solid waste processing leaders led to the development of a biomass inventory. Second, the resulting biomass was standardized to represent total dry matter. Third, woody or straw-like materials with a high lignocellulosic content were evaluated for potential energy production using combustion as a conversion technology. Heat value coefficients were determined for each individual woody or straw-like material and used to calculate the potential electrical energy and power using 20 percent conversion efficiency. Fourth, the wet biomass, represented largely by the animal manures and processing wastes, was evaluated for potential electrical energy production using anaerobic digestion as its representative conversion technology. In this process, the dry biomass was converted to available volatile solids and ultimately potential methane production using laboratory determined coefficients for each of the biomass types. From the methane production levels, estimates of electrical energy and power production were developed using 30 percent conversion efficiency. Lastly, the biomass and bioenergy databases at state and county levels across the varying categories were mapped on GIS and made web-accessible through a Visual Basic directory.
The results of this study show that Washington State has an annual production of over 16.9 million tons of underutilized dry equivalent biomass, which is capable of producing, via assumed combustion and anaerobic digestion, over 15.5 billion kWh of electrical energy or 1,769 MW of electrical power. This power total, assuming complete utilization of the inventoried biomass, is equivalent to just about 50 percent of Washington State’s annual residential electrical consumption.
Washington is blessed with a vast and diverse, annually renewable biomass that is predominantly dispersed lignocellulosic waste (forestry, field straws and yard trimmings). These materials present technical and economic challenges in collection and processing. However, about 15 percent of the available biomass is in the form of more readily biodegradable and concentrated waste streams coming from the municipal solid, animal manure and food processing wastes. Mapping of the biomass showed regional areas of concentration with the highest concentrated areas being regions where forestry and municipal or forestry and agriculture intersect, such as the Puget Sound/Cascade and Yakima regions.
The abundance, diversity and distribution of these organic resources should begin to catalyze thinking about the development of renewable fuels and energy strategies within our state. Coincidentally, the distributed nature of the resource aligns geographically with areas of the state where development of new business opportunities and jobs is of vital interest. Distributed production also possesses substantial other benefits such as decreased dependence on outside supply, price elasticity, market independence and local control all which make development of these resources a vital interest of the state.
Craig Frear is a Research Associate at the Washington State University (WSU) Department of Biological Systems Engineering. Mark Fuchs is with the state’s Department of Ecology at the Eastern Regional Office. They will provide a special presentation at the BioCycle West Coast Conference in Portland, Oregon, March 20-22, 2006. See pages 15-17 of this issue for the complete agenda and registration details.

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