(266a) Life-Cycle Assessment of Diesel Fuel and Reformulated Gasoline Blendstock Production from Natural Gas and Biomass to Liquids Conversion Processes

Transportation liquid fuels derived from natural gas (gas-to-liquids or GTL) and biomass (biomass-to-liquids or BTL) have become increasingly prominent in the United States. Increased availability of low cost natural gas coupled with the maturing of various GTL technologies readily facilitates the commercialization of GTL, primarily Fischer-Tropsch-based technology for the conversion of gas into synthetic liquid products like diesel fuel and reformulated gasoline blendstocks. In addition to the economic feasibility, overarching concerns such as the environmental sustainability also need to be addressed to ensure sustainable transportation liquid fuels production. According to the U.S. Energy Information Administration’s Annual Energy Outlook 2014 Early Release, the transportation sector accounts for about 72% of US oil consumption, and at the same time contributes up to 34% of the nation’s greenhouse gas (GHG) emissions [1]. As biomass is the only renewable resources that can be used to produce liquid fuels to supplement or replace petroleum-based transportation fuels, GTL technology can potentially be enhanced with biomass to improve the sustainability of its products. A portion of CO₂ emissions from the fuels production from BTL and vehicle operation is biogenic CO₂ (i.e., CO₂ absorbed from the atmosphere and incorporated into biomass during the feedstock production phase). With its biomass origin, biogenic CO₂ does not contribute to the increase of GHG in the atmosphere. Consequently, co-conversion of natural gas with biomass to liquid fuels (GBTL) may simultaneously increase fuel yields, reduce fuel production costs, and decrease overall life-cycle GHG emissions. The life-cycle GHG emissions for fuels derived from BTL refineries are relative low (> 150% GHG emissions reduction compared to petroleum-based fuels) due to biogenic CO₂ in the fuel and carbon sequestration by biochar. A similar GHG emissions reduction can also be realized when co-converting natural gas with biomass to diesel fuel and gasoline blendstock, as evidenced in GBTL life-cycle GHG emissions results. Results from various BTL and GBTL scenarios will be presented and discussed.

[1] AEO2014 Early Release Overview, http://www.eia.gov/forecasts/aeo/er/pdf/0383er(2014).pdf