Processes for converting methane to liquid fuels: Economic screening through energy management

Numerous process schemes have been proposed for converting methane to liquid hydrocarbon fuels. Economic evaluation studies generally conclude that none except the best of these schemes are attractive at present oil prices of <20 $/bb1. Simple arguments are presented here to show why methane conversion processes are now not economically attractive and what needs to be done to improve on their economics. Particularly, an analysis of numerous fuel manufacturing processes based on coal, oil and gas feedstock will show the need to increase the plant scale, and reduce the energy losses as well as the overall heat and momentum transfer duty. Furthermore, simple calculations of the overall transfer duty of various methane conversion routes for liquid fuel manufacture allow us to rank them according to their expected capital cost and identify the improvements required for making each route competitive with the cheapest scheme identified here. The conversion routes considered here include methane pyrolysis, oxidative coupling, partial oxidation to methanol, methylchloride and methylbisulfate as well as the commercial routes based on synthesis gas.