Argonne GREET 2018 update

In Illinois, a research team at Argonne National Lab released its GREET 2018 update. GREET 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). There are two GREET modeling platforms; GREET Excel is a multidimensional spreadsheet model that provides a comprehensive LCA tool, and GREET.Net provides an interactive graphical toolbox to perform LCA. The GREET 2018 release includes expansions and updates for both platforms, and this report provides a summary of the release.

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. EO is produced via direct oxidation of bio-derived ethylene with oxygen, while bio-derived EG is produced by the hydration of bio-derived EO. There are several pathways to produce bio-TPA, such as direct fermentation of sugars and via an isobutanol intermediate to paraxylene. However, we assessed the latter because companies are actively working to produce paraxylene from isobutanol at a demonstration scale (e.g., Gevo), while the direct fermentation pathway is now less mature than the isobutanol route.

In CCLUB 2018, users can select additional option for tillage practice – U.S. Average – to calculate soil organic carbon (SOC) changes at a national level. This option calculates the weighted average of SOC changes based on the share of corn-planted area using different types of tillage – no till (16%), reduced tillage (59%), and conventional tillage (25%). CCLUB now uses the U.S. Average for a baseline tillage practice. For soy biodiesel land use change (LUC) scenarios, CCLUB includes new updates to specifically estimate emissions associated with peatland loss in Southeast Asia

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 (Davis et al. 2018). A key difference between the pathways included in this update and those presented in the report is that the harmonization study considered polyurethane and succinic acid coproducts from the CAP pathway with associated displacement of emissions and resource use for those coproducts; GREET 2018-relevant default pathways only consider the option without production of coproducts.

Argonne updated the pathway to produce high-octane gasoline via indirect liquefaction. The update takes into account the newly developed design case by a joint national lab team for the DOE Bioenergy Technology Office, which uses logging residues as the feedstock. The update reflects improvements in biofuel yield and process material, energy, and water consumption in the conversion step, as well as improvements in the energy efficiency of the advanced feedstock logistics.

Argonne also added a new pathway that examines renewable hydrocarbon fuels produced from ex-situ catalytic fast pyrolysis. The update takes into account the newly developed design case by the joint national lab team for a conversion that uses a blend of logging residues and clean pine as the feedstocks. The update reflects improvements in biofuel yield and process material, energy, and water consumption in the conversion step, as well as improvements in the energy efficiency of the advanced feedstock logistics for both logging residues and clean pine.