The fuel cycle for a given transportation fuel includes the following processes: energy feedstock (or primary energy) production; biomass feedstock transportation and storage; fuel production; fuel transportation, storage, and distribution; and vehicle operations that involve fuel combustion air or other chemical energy conversions. The processes that precede vehicle operations are often referred to as the well-to-pump (WTP) stage, the vehicle operations are referred to as the pump-to-wheels (PTW) stage, and the entire fuel cycle is referred to as the well-to-wheels (WTW) cycle. Various models have been developed that allow researchers to conduct fuel cycle analyses of vehicle/fuel systems. The GREET (greenhouse gases, regulated emissions, and energy transportation) model, developed by Argonne National Laboratory, is in the public domain and, so far, more than 1000 users worldwide have used the model to predict the energy use and emissions associated with alternative fuels vehicles. The GREET model and its documents are posted on the Internet at http:// greet.anl.gov. (more…)
