Life Cycle Analysis of Fischer-Tropsch Diesel Produced by Tri-Reforming and Fischer-Tropsch Synthesis (TriFTS) of Landfill Gas

Renewable liquid fuels production from landfill waste provides a promising alternative to conventional carbon-intensive waste management methods and has the potential to contribute to the transition toward low-carbon fuel pathways. In this work, we investigated the life cycle greenhouse gas (GHG) emissions of producing Fischer-Tropsch diesel from landfill gas (LFG) using the TriFTS catalytic conversion process and compared it to fossil-based petroleum diesel. A life cycle-based comparison was made between TriFTS diesel and other LFG waste management pathways, LFG-to-Electricity and LFG-to-Compressed renewable natural gas (RNG), on a per kilogram of feedstock basis as well as on a per MJ of energy basis, which also included the LFG-to-Direct Combustion pathway. The study considered flaring of LFG as the common underlying counterfactual scenario for all of the waste-to-energy product pathways. We estimated the life cycle GHG emissions for TriFTS diesel to be -36.4 carbon dioxide equivalent (grams CO(2)e)/MJ which is significantly lower than its fossil fuel counterpart which was estimated to be 90.5 g CO(2)e/MJ on a cradle-to-grave basis. The life cycle emission results from both perspectives (per kg feedstock and per MJ energy output) show that TriFTS diesel is a viable alternative energy pathway from LFG when compared to other pathways, primarily due to the main product being a renewable fuel that can serve as a drop-in fuel for diesel-based uses, within both the waste industry as well as the larger market. Further sensitivity analysis was performed based on the production of TriFTS diesel with the counterfactual waste management scenario of LFG-to-Flaring as well as the alternative LFG-to-Electricity waste management pathway. The sensitivity of the carbon intensity for TriFTS diesel to flaring efficiency and the carbon intensity of the electricity grid were also investigated. The study highlights the potential for the TriFTS conversion process technology to contribute to the waste industry's closed loop and decarbonization initiatives and to provide low carbon fuel for transportation.