The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) Model

GREET 1.8b - September 5, 2008 (download)

What's New in GREET1.8b?

• New fuel production pathways
• Brazilian sugarcane ethanol
• Corn to butanol
• Soybeans to renewable diesel via hydrogenation
• Coal/biomass co-feeding for Fitscher-Tropsch diesel production
• Various corn ethanol plant types with different process fuels
• Pet coke to H₂ production
• Enhancements of existing pathways
• Inclusion of three methods in dealing with co-products for soybean-based biodiesel
• Compression energy efficiencies for natural gas and H₂ are calculated with the first law of thermodynamics
• Tube trailer delivery option for gaseous H₂ to refueling stations
• Revision of petroleum refining energy efficiencies
• Updated petroleum refinery processes to include H₂ from different feedstock sources
• Updated corn farming energy use to 2001 data from the USDA farm survey
• Updated displacement ratios between distillers grains and soluables vs. conventional animal feeds

GREET 2.7 - August 30, 2007 (download)

How Does GREET Work?

To fully evaluate energy and emission impacts of advanced vehicle technologies and new transportation fuels, the fuel cycle from wells to wheels and the vehicle cycle through material recovery and vehicle disposal need to be considered. Sponsored by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE), Argonne has developed a full life-cycle model called GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation). It allows researchers and analysts to evaluate various vehicle and fuel combinations on a full fuel-cycle/vehicle-cycle basis.

GREET was developed as a multidimensional spreadsheet model in Microsoft Excel. This public domain model is available free of charge for anyone to use. The first version of GREET was released in 1996. Since then, Argonne has continued to update and expand the model. The most recent GREET versions are GREET 1.8b version for fuel-cycle analysis and GREET 2.7 version for vehicle-cycle analysis.

For a given vehicle and fuel system, GREET separately calculates the following:

• Consumption of total energy (energy in non-renewable and renewable sources), fossil fuels (petroleum, natural gas, and coal together), petroleum, coal and natural gas.
• Emissions of CO2-equivalent greenhouse gases - primarily carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O).
• Emissions of six criteria pollutants: volatile organic compounds (VOCs), carbon monoxide (CO), nitrogen oxide (NO_x), particulate matter with size smaller than 10 micron (PM10), particulate matter with size smaller than 2.5 micron (PM2.5),and sulfur oxides (SO_x).

GREET includes more than 100 fuel production pathways and more than 70 vehicle/fuel systems. General fuel production pathways are shown in the chart below:

GREET covers the following vehicle technologies :

• Conventional spark-ignition engines
• Direct-injection, spark-ignition engines
• Direct injection, compression-ignition engines
• Grid-independent hybrid electric vehicles
• Grid-connected (or plug-in) hybrid electric vehicles
• Battery-powered electric vehicles
• Fuel-cell vehicles

To address technology improvements over time, GREET simulates fuel production pathways and vehicle systems over a period from 1990 to 2020, in five-year intervals.

Uses of GREET

Argonne has used GREET to evaluate various engine and fuel systems for DOE, other government agencies, and industry (see publications list). In addition, other organizations have used GREET for their evaluation of advanced vehicle technologies and new transportation fuels. GREET users include government agencies, the auto industry, the energy industry, research institutions, universities, and public interest groups. GREET users are spread in North America, Europe, and Asia.