Argonne National Laboratory’s Systems Assessment Group announced the 2018 release of the suite of GREET models and associated documentation.

The GREET model is a life-cycle analysis (LCA) tool, structured to systematically examine energy and environmental effects of a wide variety of transportation fuels and vehicle technologies in major transportation sectors (i.e., road, air, marine, and rail).

Among the major expansions and updates in the 2018 model set are:

• 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 the 2018 release, we added three bio-derived products: bio-ethylene oxide (EO), bio-ethylene glycol (EG), and bio-terephthalic acid (TPA). These bio-derived products can be used in the production of polyester and plastics such as polyethylene terephthalate (PET, the raw material for plastic bottles), liquid coolants, and solvents.

• Argonne updated two algae biofuel pathways, combined algae processing (CAP) and hydrothermal liquefaction (HTL), based on pathway parameters identified in an Argonne collaboration with the National Renewable Energy Laboratory (NREL) and Pacific Northwest National Laboratory (PNNL) to harmonize LCA results (together with techno-economic analysis [TEA] results) for algal biofuel production pathways.

• To estimate the energy use and air emissions of byproduct hydrogen from steam crackers, Argonne added a by-product hydrogen production from steam crackers pathway to GREET 2018. Two byproduct hydrogen treatment scenarios were included: substitution and mass allocation. In the first scenario (substitution), byproduct hydrogen, which is used internally as a combustion fuel for the cracking process, may be diverted from the combustion fuel stream, and its thermal energy that was used for the cracking process is substituted with combustion of natural gas. The second scenario refers to byproduct hydrogen that is already being exported to external markets. In this case, hydrogen is a coproduct, along with ethylene and other products, and the mass allocation method is appropriate to distribute the cracking process energy use and air emissions burden between all products, including hydrogen.

• In addition to the hydrogen fuel-cell electric freight trucks and school buses that were already included in GREET 2017, Argonne added hydrogen fuel-cell electric transit bus technology to GREET 2018.

• Refined metallic cobalt and cobalt chemical production pathways were updated in GREET 2018. The updated life-cycle inventory (LCI) covers material and energy flows associated with cobalt ore mining, cobalt ore processing, cobalt chemicals production, cobalt metal production, and pertinent transportation activities. The updates were based on recent literature, industry statistics, and company reports, and represent current practices of the global cobalt industry.

• In GREET 2018, updates were made in the battery LCA module for (1) bill-of-materials (BOMs) of lithium-ion batteries (LIBs) for electric vehicles (EVs), including hybrid electric vehicles (HEVs), plug-in hybrid vehicles (PHEVs), and battery electric vehicles (BEVs); (2) LCI for the production of LIB cathode materials, including lithium cobalt oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

• In GREET 2018, Argonne added carinata-derived jet fuel production pathways via hydroprocessed esters and fatty acid (HEFA) conversion pathways. GREET 2017 already included aviation fuels produced from soybean, palm, jatropha, rapeseed, and camelina, and canola through HEFA conversion. The new pathway reflects a new attempt to use oil extracted from brassica carinata seeds to produce jet fuels via the HEFA conversion pathway.