Life Cycle Assessment of Renewable Hydrocarbon Fuels Produced by the New Cool Gas to Liquid (Cool GTL) Process

Abstract

The Cool Gas-to-Liquid (Cool GTL) process converts biogas and captured CO₂ into renewable hydrocarbon fuels, contributing to GHG emissions reduction in transportation. This report explains a Life Cycle Assessment (LCA) study that was completed to evaluate the environmental impact of different feedstocks, hydrogen sources, and electricity inputs. The analysis considers biogas from food waste, manure, and landfill sources, as well as biogenic, fossil, and direct air capture (DAC) CO₂ feedstocks. Results show that biogas pathways provide the greatest GHG reductions, with the best case (food and manure biogas + solar hydrogen + solar electricity) achieving a net-negative GWP of -60.2 g CO_2eq/MJ fuel, representing a 171% reduction compared to conventional fossil jet fuel emissions. Biogenic CO₂ feedstocks also lead to a 69% reduction in emissions (26.1 g CO_2eq/MJ fuel) but require renewable inputs. Fossil CO₂ and DAC pathways often yield higher emissions, with the worst DAC scenario reaching 205.8 g CO_2eq/MJ fuel, surpassing fossil jet fuel emissions. Findings emphasize the need to prioritize biogas, transition to green hydrogen, and use renewable electricity for sustainability.