关键词：生物质转换;成本收益分析;环境影响;乙醇;燃料;石油产品;能量转换
摘 要：Arguments appear almost daily in the media that biofuels will increase our domestic supply of transportation fuel, end our dependence on foreign oil, reduce military vulnerabilities on the battlefield, and improve national security. Biofuels are further touted to reduce fuel price volatility, polluting emissions, and greenhouse gases (GHG), and stimulate the economy. The promise and curse of biofuels is that they are limited by the energy that living organisms harvest from the sun and suffer a fatal 'catch-22': uncultivated biofuel yields are far too small, diffuse, and infrequent to displace any meaningful fraction of U.S. primary energy needs, and boosting yields through cultivation consumes more energy than it adds to the biomass. Furthermore, the harvested biomass requires large amounts of additional energy to convert it into the compact, energy-rich, liquid hydrocarbon form required for compatibility with the nation's fuel infrastructure, transportation sector, and especially the military. The energy content of the final-product biofuel compared to the energy required to produce it proves to be a very poor investment, especially compared to other alternatives. In many cases, there is net loss of energy. The United States cannot achieve energy security through biofuels, and even the attempt is ironically achieving effects contrary to 'clean' and 'green' environmental goals and actively threatening global security. This article focuses on cultivated biomass converted into liquid transportation fuel. The overall approach is an analysis of alternatives comparing three distinct biofuels methodologies with conventional petroleum fuel to assess their relative costs and benefits. The article provides evidence that pursuit of biofuels creates irreversible harm to the environment, increases greenhouse gas emissions, undermines food security, and promotes abuse of human rights. The article concludes with specific recommendations for policy and action.