What does a renewable power system look like that is reliable whatever the weather? We make the case for e-methanol with carbon cycling.
Methanol is combusted in pure oxygen in an Allam cycle turbine; this allows easy capture of high-pressure, pure carbon dioxide; the carbon dioxide is then cycled back for more methanol synthesis together with green hydrogen.
Compared to hydrogen storage, which is only cost-effective where salt deposits allow salt caverns to be built, methanol can be stored anywhere in aboveground tanks, just like oil products. The synthesis losses are partly offset by the lack of need for compression (versus hydrogen) and high efficiency of the Allam turbine (MeOH round-trip efficiency is 35% versus 38% for H2).
IEEE Spectrum article: https://spectrum.ieee.org/methanol-energy-storage