Argonne National Laboratory’s (ANL) Systems Assessment Group has released the 2018 suite of GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) models and associated documentation. The GREET model is a life-cycle analysis (LCA) tool, structured to systematically examine energy and environmental effects of a variety of transportation fuels and vehicle technologies in major Source: ANLSource: ANLtransportation sectors.

The updates to the 2018 model set expand the GREET bioproduct module to assess environmental impacts of bio-derived chemicals produced from biochemical, biological and thermochemical conversion technologies. Three bio-derived products are now included: bio-ethylene oxide, bio-ethylene glycol and bio-terephthalic acid. 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.

Two algae biofuel pathways - combined algae processing and hydrothermal liquefaction - were also updated, based on pathway parameters identified in an ANL collaboration with the National Renewable Energy Laboratory and Pacific Northwest National Laboratory to harmonize LCA results for algal biofuel production pathways.

To estimate the energy use and air emissions of byproduct hydrogen from steam crackers, ANL added a byproduct hydrogen production from steam crackers pathway to GREET 2018. Two byproduct hydrogen treatment scenarios were included: substitution and mass allocation. In the substitution scenario, 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 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.

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.

Updates were also made in the battery LCA module for bill-of-materials of lithium-ion batteries (LIBs) for electric vehicles, including hybrid electric vehicles, plug-in hybrid vehicles and battery electric vehicles; and LCI for the production of LIB cathode materials, including lithium cobalt oxide, lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide.

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