Argonne releases 2018 update to GREET model

By Erin Voegele | October 15, 2018

On Oct. 10, Argonne National Laboratory’s System Assessment Group released a 2018 update of its GREET Model, which is an analytical tool used to consider the life cycle of various transportation fuels. The GREET model is used in a variety government rulemakings, including the proposed SAFE Vehicles Rule that aims to establish corporate average fuel economy (CAFE) and greenhouse gas (GHG) standards for model year (MY) 2021-2026 vehicles. 

According to Argonne, the greenhouse gases, regulated emissions and energy use in transportation (GREET) model is a life-cycle analysis tool that is designed to systematically examine energy and environmental effects of a wide variety of transportation fuels and vehicle technologies in major transportation sectors, including road, air, marine and rail.

Many in the biofuels industry have previously criticized the GREET model for its treatment of ethanol. While versions of GREET released in recent years improved the modeling for corn ethanolinformation released on the 2018 GREET update by Argonne does not list any major changes in the model’s specific treatment of ethanol. However, the update does include changes for biofuels and bioproducts, hydrogen and fuel cell vehicles, electricity and electric vehicles, and battery life-cycle analysis.

Regarding biofuels and bioproducts, Argonne said “GREET 2018 continues to expand the GREET bioproduct module to assess environmental impacts of bio-derived chemicals produced from biochemical, biological and thermochemical conversion technologies.” For 2018, three bio-derived products were added to the model, including bioethylene oxide (EO), bioethylene glycol (EG) and bioterephthalic acide (TPA). Information released by Argonne explains these three bio-derived products can be used to produce polyester and plastics, liquid coolants and solvents.

The 2018 update also makes changes in the carbon calculator for land use change from biofuels production (CCLUB). According to Argonne, users are now able to select an additional option for tillage practice, “U.S. Average,” to calculate soil organic carbon (SOC) changes on a national level. The option calculates the weighted average of SOC changes based on the share of corn-planted areas using different types of tillage, including no till (16 percent), reduced tillage (59 percent), and conventional tillage (25 percent). A fact sheet on the updated model states that CCLUB now uses “U.S. Average” for a baseline tillage practice. For soy biodiesel land use change (LUC) scenarios, the fact sheet states that CCLUB now includes new updates to specifically estimate emissions associated with peatland loss in Southeast Asia.

GREET 2018 also updates two algae biofuel pathways, including combined algae processing (CAP) and hydrothermal liquefaction (HTL). In addition, Argonne updated the pathway to produce high-octane gasoline via indirect liquefaction and added a new pathway that examines renewable hydrocarbon fuels produced from ex-situ catalytic fast pyrolysis.

A fully summary of expansions and updates in the model can be downloaded on Argonne’s GREET webpage.