Analysis of transportation systems on a life-cycle basis permits us to better understand the breadth and magnitude of impacts produced when vehicle systems are operated on different fuels or energy options like electricity or hydrogen. Such detailed analysis also provides the granularity needed to investigate policy implications, set R&D goals, and perform follow-on impact and policy assessments. With the support of several programs within the US Department Energy’s Office of Energy Efficiency and Renewable Energy, the Systems Assessment Group in Argonne’s Energy Systems Division has been developing the GREET (Greenhouse Gases, Regulated Emissions, and Energy use in Transportation) model to provide a common, transparent platform for lifecycle analysis (LCA) of alternative combinations of vehicle and fuel technologies.
Vehicle technologies include conventional internal combustion engines, hybrid electric systems, battery electric vehicles, and fuel cell electric vehicles. Fuel/energy options include petroleum fuels, natural gas-based fuels, biofuels, hydrogen, and electricity. LCAs conducted with the GREET platform permit consideration of a host of different fuel production, and vehicle material and production pathways, as well as alternative vehicle utilization assumptions. LCA results include energy use (by different energy sources), emissions of greenhouse gases (in terms of CO2 equivalent) and emissions of air pollutants. Water consumption will be added in a new GREET release. GREET includes all transportation modes – on-road vehicles, aircraft, marine vessels, and rail (to be added in a new GREET release). The Systems Assessment Group has conducted various LCAs of vehicle/fuel systems for DOE and other agencies. The GREET model and its results are used by government agencies, industries, and academia. There are more than 20,000 registered GREET users.