Evaluation of Cradle to Grave Impacts From Potential Automotive Fuel Replacements: An Update

In modern society, everything from transportation to commerce to food supply is heavily dependent on the availability of cheap and plentiful energy supplies. In the past few years many have realized that the traditional sources of energy — oil and gas — are in limited supply and that we need to prepare for the approaching production maxima. Recent research has focused on alternative forms of transportation energy including biofuels, unconventional refining techniques, and heavy oil and bitumen. This report is a continuation of earlier research and now considers ethanol produced from municipal solid waste, ethanol from algae, and compressed natural gas. The data presented are maintained in the same format as previous studies to facilitate comparison between the fuels. Results are reported for land use, water use, input-to-output energy ratio, and carbon emissions for each fuel cycle and source. Data are given for the cases of 10, 25, and 50 percent displacements of the 2012 predicted transportation energy needs (i.e., the equivalent of 430 million gallons of gasoline per day). Cradle-to-grave findings indicate that some novel fuels cannot substitute for conventional fuels without consuming more water or land and emitting more greenhouse gases than fuels in use today. The life cycle analysis approach presented here is that which should be used as the US moves toward low carbon fuel standards (LCFS) and carbon cap and trade (CC&T) approaches for reducing carbon loading of the environment.