It's now pretty clear that chemical fuel systems, i.e. any system based on the combustion of a fuel with oxygen to generate heat/pressure/motive force, are goin

It's now pretty clear that chemical fuel systems, i.e. any system based on the combustion of a fuel with oxygen to generate heat/pressure/motive force, are going to be fairly niche markets in the future. International jet travel and orbital launch rockets, and maybe long-distance commercial shipping, are about it. The real value of renewable-energy-powered chemical synthesis will be in the production of things like fertilizers, dyes, carbon fiber, etc. Basically you can take the entire fossil-fuel-sourced front end of the petrochemical industry and replace it with hydrogen and carbon inputs from water and atmospheric CO2 respectively.