GREET: Vehicle Energy & Emissions Modeling

GREET chart, src: http://www.transportation.anl.gov/modeling_simulation/GREET/

GREET stands for “Greenhouse gases, Regulated Emissions and Energy use in Transportation”. It is a model from the U.S. Department of Energy’s (DOE) Argonne National Laboratory aimed at evaluating and comparing the energy and environmental impacts of various new fuels and vehicle technologies. For instance, when debating the benefits of corn ethanol fuel, GREET is a tool that allows one to calculate total energy use and greenhouse gas emission. For energy use, GREET calculates both the well-to-pump (i.e in production and distribution of the fuel to be used by the vehicle) and pump-to-wheels (i.e. the energy consumed by the vehicle). Corn ethanol’s well-to-pump energy is often blamed for lowering the usefulness of that fuel. What if the ethanol comes from Brazilian sugarcane instead of US corn? GREET can model that as well. In can also model the energy used in the production of the vehicle for a full life-cycle assessment.

One can imagine GREET supporting OR vehicle applications such as designing a fleet of vehicles with desired energy usage and emission profiles (including minimal, or at least capped by some limit). And this could work much like the way renewable portfolio standards (RPS) are being tested in large-scale electric power models with the goal of capping emissions while minimizing cost impact. Like the RPS, vehicles with advanced low-energy and low-emissions fuels and technologies would help reduce negative environmental impacts, while likely incurring greater cost in the short-term. Various vehicle and fuel mixes aimed at meeting energy/environment goals subject to cost, policy and other constraints could be analyzed.

GREET has been used widely. See this list of publications for numerous examples. It is available free of charge from Argonne’s web site here. For more information see the site as well as this press release.

Update: Paper comparing GREET to the BESS tool in the context of corn ethanol – Richard J. Plevin, Modeling Corn Ethanol and Climate: A Critical Comparison of the BESS and GREET Models, Journal of Industrial Ecology, Volume 13 Issue 4, Pages 495 – 507, Published Online: 25 Jun 2009