Selection of a biomass processing technology

The drive to use an increasing fraction of non-fossil renewable energy is growing around the world, to reduce the growth of greenhouse gases (GHG) in the atmosphere. Since there are many primary sources of renewable energy, e.g. wind, biomass, solar, and multiple end uses of the energy, e.g. transportation fuel and electricity, selections of appropriate sources, processing routes and end products are required.;Biomass processes have an optimum size that results from the tradeoff between transportation and processing cost. The yield, optimum size, and processing cost are analyzed for each processing alternative. Life cycle assessment (LCA) is used to estimate the reduction in GHG emissions from each of the four processing schemes as compared to a "business as usual" case using fossil fuel. Cost and LCA emission data are then combined to calculate the required carbon credit subsidy, measured in dollars per tonne of avoided carbon dioxide equivalent, to have the biomass process earn a 12% return on total capital investment. The criterion for process selection is minimum carbon credit. The selection between alternate end forms of energy, in this study electricity and transportation fuel, depends on the prices of oil and electricity.;In this study we take a major renewable energy resource, straw and corn stover (agricultural residues), and explore four processing alternatives to make two end products. Direct combustion with a conventional steam cycle and biomass integrated gasification and combined cycle (BIGCC) each produce electricity. Enzymatic hydrolysis and fermentation produces ethanol which can substitute for gasoline, while oxygen gasification and Fischer Tropsch processing produces a synthetic diesel that can replace conventional diesel fuel.