https://www.publicpower.org/system/files/documents/Americas-...
Even during WWII Germany had to synthesize much of its hydrocarbon fuel.
Also after the war there has been large-scale production of synthetic hydrocarbons, but eventually this was abandoned due to the low price of fossil oil.
It is possible to synthesize hydrocarbons from syngas, which can be made from carbon dioxide and water, with solar energy. If the carbon dioxide is extracted from air, that requires much more energy than when a concentrated source of CO2 is available, but with essentially free solar energy it would still be feasible.
Obviously, this will not be done as long as cheaper fossil hydrocarbons are offered. However the use of fossil hydrocarbons for plastic, asphalt or other applications that do not release CO2 is not harmful.
Germany [0], as well as Apartheid South Africa (SASOL), and now China, synthesized that fuel from coal. Which is itself a fossil fuel.
[0] https://warhistory.org/@msw/article/synthetic-production-of-...
> Obviously, this will not be done as long as cheaper fossil hydrocarbons are offered. However the use of fossil hydrocarbons for plastic, asphalt or other applications that do not release CO2 is not harmful.
The issue with any fuel/feedstock production is not just the financial cost but the amount of energy returned on the energy invested. A modern civilization (like Japan) requires 10:1. Synfuels made using the method you described are 1:1 - they provide as much energy as it takes to make them.
The same technology can be used with carbon monoxide made by reducing the carbon dioxide from air. This requires more energy, but when that is provided by solar energy, this is no longer a problem.
If the energy used to make synfuel is solar, it is an external input and it does not matter much which is the ratio between it and the energy stored in synfuel, except that it determines the profitability of a plant during the first years of operation, as it determines the ratio between the quantity of fuel produced in an interval of time and the installed power of solar panels.
While this ratio determines the time in which the initial investment can be recovered, it matters little for the ongoing expenses required for production, which will vary very little when the ratio varies in a large range, so it has little influence on the production cost after the assets are depreciated.
Which is why we aren't doing already.
First, fossil fuels currently are used to generate about 60% of the world's electricity. Nearly all of that could be replaced with renewables plus batteries.
Second, only around 20% of fossil fuel used for transportation is used in aviation or marine transportation. Most of the remaining 80% could be replaced by electric vehicles.
Overall something like 75% of what fossil fuels are extracted for could be replaced with renewables, leaving marine and aviation transportation and things that are not using them for their combustion chemistry.