非常规的化石燃料经济和环境权衡Unconventional Fossil-Based Fuels Economic and Environmental Trade-Offs

石油发动机燃料的价格和二氧化碳（CO2）排放的关注正在引起人们对可能替代物的关注。2008年，经通胀因素调整后，世界石油价格创下历史新高，延续了数年来的价格上涨格局。从传统原油中提取的石油产品占美国最终使用能源供应量的50%以上，占美国运输部门全部能源使用量的95%以上。来自石油消费的排放量占全国二氧化碳排放量的44%，其中约33%的国家由运输燃料使用造成的二氧化碳排放（EIA，2007年A）。近期和中期（约10-20年）通常考虑的替代运输燃料选择包括生物质燃料（如乙醇、生物柴油）和非传统化石燃料液体燃料，这些燃料来源于重油、油砂、油页岩和煤液化。

Both the price of petroleum motor fuels and concerns regarding emissions of carbon dioxide (CO2) are driving attention to possible substitutes. In 2008, the world price of oil reached record highs after being adjusted for inflation, continuing a pattern of price increases over several years. Petroleum products derived from conventional crude oil constitute more than 50 percent of end-use energy deliveries in the United States and more than 95 percent of all energy used in the U.S. transportation sector. Emissions from the consumption of petroleum account for 44 percent of the nation’s CO2 emissions, with approximately 33 percent of national CO2 emissions resulting from transportation-fuel use (EIA, 2007a). Commonly considered alternative transportation-fuel options for the near and medium terms (roughly 10–20 years) include both biomass-based fuels (e.g., ethanol, biodiesel) and unconventional fossil-based liquid fuels derived from such sources as heavy oils, oil sands, oil shale, and coal liquefaction.