Techno-economic study of the storage of fluctuating renewable energy in liquid hydrocarbons

Liquid hydrocarbons are considered as an option to store renewable energy while decoupling the supply and demand of renewable resources. They can also be used as transportation fuel or as feedstock for the chemical industry and are characterized by a high energy density. A process concept using renewable energy from fluctuating wind power and CO2 to produce liquid hydrocarbons was modeled by a flowsheet simulation in Aspen Plus®. The capacity of the plant was set to 1GWLHV of hydrogen input, using water electrolysis, reverse water-gas shift reaction (RWGS) and Fischer-Tropsch (FT) synthesis. A feed of 30t/h of H2 generated 56.3t/h (12,856bbl/d) of liquid hydrocarbons. A Power-to-Liquid efficiency of 44.6% was calculated for the base case scenario. Net production cost ranged from 12.41$/GGE to 21.35$/GGE for a system powered by a wind power plant with a full load fraction of about 47%, depending on the assumed electricity feedstock price and electrolyzer capital cost. For systems with full load fractions between 70% and 90%, the production cost was in the range of 5.48$/GGE to 8.03$/GGE.