Life-Cycle Assessment of Unconventional Methane Feedstock Procurement

This study involves collaborating with a team of researchers in an ARPA-E project to investigate the feasibility of utilizing stranded, small-scale sources of natural gas to produce liquid transportation fuels and value added chemicals. In addition to technical and economic considerations, environmental impacts are being studied through a cradle-to-gate life-cycle assessment approach. Here, we present preliminary findings for the initial stages of the fuel life cycle, involving methane procurement and compression for use in a conversion reactor. We have defined several potential scenarios for using methane derived from stranded gas, associated gas, and landfill gas. The requirements for procuring each gas stream are taken into account, along with fugitive emissions and considerations of alternate usage for each gas stream. Compression requirements were evaluated in consultation with LanzaTech process engineering estimates. Environmental impacts being considered are global warming potential and fossil energy demand. Initial results reveal that major differences emerge between potential gas feedstock scenarios based upon alternate fate of the gas (flaring vs. utility generation, for instance). Estimated fugitive emissions rates also play a large role in determining the embodied global warming potential of feedstock gases and will need to be thoroughly documented in each commercial setting to verify optimal performance.