Woody Biomass Supply, Economics, and Biofuel Policy

Abstract

The amount of woody biomass available for biofuel production depends on tree growth rate, harvesting techniques, harvest cost, government policies, and established traditions within the industry. Comparing estimates of biomass availability across studies is difficult because of different methodologies for estimating biomass supply, compounded by inconsistent and often unspecified assumptions. Studies differ in their definition of biomass (i.e., tree size, parts of tree) and consideration of ecological and economic factors (i.e., harvest productivity and costs, competing demand, compliance with existing regulations). In particular, existing restrictions on bio-mass harvesting for biofuels under the Federal Renewable Fuel Standard often are not included. Additionally, because most biomass availability studies ignore current biomass uses, an overestimation of available bio-mass for future uses results. Presented are new estimates for the amount of economically available biomass in Maine, taking into consideration both economic (integrated harvesting for pulp and precommercial thinning) and ecological factors. It is found that biomass availability varies greatly, depending on the relative location of the biorefinery, biomass harvesting site, and existing wood consumers (e.g., pulp mill). Indeed, harvesting and transporting woody biomass without an existing use for the high-value forest products (saw logs and pulp) probably makes woody biomass for energy production uneconomical. This finding is contrary to some existing studies and suggests that economic consideration needs greater emphasis in estimating biomass availability for biofuels.