(390e) A Life Cycle Analysis of the Conversion of Landfill Gas to Fischer-Tropsch Diesel By Tri-Reforming and Fischer-Tropsch Synthesis (TriFTS)

The waste industry remains a hard-to-decarbonize sector with conventional waste management methods being carbon-intensive. A promising alternative to these methods could be the production of renewable liquid fuels from biomass-derived landfill gas. These renewable liquid fuels have the potential to play a significant role in the transition to low-carbon fuel pathways. In this paper, we take a closer look at the production of Fischer-Tropsch diesel from landfill gas using the catalytic conversion Tri-Reforming and Fischer-Tropsch Synthesis process or TriFTS® process. We investigated the life cycle greenhouse gas (GHG) emissions of the TriFTS diesel production process and compared it with conventional petroleum diesel produced from fossil sources. A life cycle-based comparison was also made between TriFTS diesel and other landfill waste management pathways - the conversion of landfill gas to power and landfill gas to compressed renewable natural gas - on a per kilogram of feedstock basis as well as a per MJ of energy basis. The study assumed the conventional waste management method of flaring landfill gas as the underlying counterfactual scenario for the investigated waste-to-energy product pathways. We estimated the life cycle GHG emissions for TriFTS diesel to be -36.4 carbon dioxide equivalent (grams CO₂e)/MJ which is much lower than its fossil fuel counterpart which was estimated to be 90.5 grams CO₂e/MJ on a cradle-to-grave basis. The life cycle emission results from both functional unit perspectives 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, both within the waste industry as well as the larger transportation fuels market. Additional sensitivity analysis was performed based on the production of TriFTS diesel with counterfactual waste management scenarios of flaring and electricity production from landfill gas. The sensitivity of the TriFTS diesel carbon intensity to flaring efficiency, thermal power combustion efficiency as well as the carbon intensity of the electricity grid were also investigated. An extension of this work to study the life cycle impacts of the production of TriFTS diesel from other biomass-based feedstock including sludge deposits from wastewater treatment plants and swine manure is also considered. The paper highlights the potential for the TriFTS energy conversion technology to contribute to the waste industry’s decarbonization initiatives, and to provide low carbon fuel for transportation.