The replacement has already started in earnest, hence BEV forums such as this.WetEV wrote: ↑Tue Feb 04, 2020 4:07 pmRenewable energy will be replacing fossil energy over decades. Any diverted to make rocket fuel here, or worse on Mars, will slow this process. First launch to Mars Musk has announced will be in 2022. That takes a huge blunt to believe.
There would be no diversion, but displacement. Solar PV continues to grow rapidly and there will be many times a year, in just the next few years, where solar PV generation would be curtailed if no where to park (battery) or use those electrons (electrolysis/H2 tech now and synthetic fuels down the road).