> An area of research that I don't hear much about is creating hydrocarbon fuels for applications that really need them, like airplanes. Essentially, using hydrocarbons as a chemical battery instead of an out-of-the-ground energy source.
Oh yes, I was going to comment on exactly that point.
> The chemistry is complicated
That depends on which type of fuel you are talking about. If you can use Methane (AKA Natural Gas), then you could use the Sabatier reaction (https://en.wikipedia.org/wiki/Sabatier_reaction). You need CO2 (which is what we want to remove) and Hydrogen (which is the energy consuming part). Then you have to compress it (more energy).
The advantage of adding CO2 to the mix(instead of just burning hydrogen) is that it becomes much easier to store and you have decent energy density.
Of course, that's not Jet-A. If you really need that (turbines don't care too much, but logistics and storage will care), then you need to use something else. Eg.
https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_proces...
As I understand it, that's what the Navy was struggling against.
But forget about the energy costs, think about human labor costs. Because if you can reduce labor to zero and have these things be self-sufficient, then we really don't care about energy costs. Stick a bunch of these fuel facilities wherever they will fit, power them with whatever renewables are available, wait a bit, then come back to collect.
I think the first large scale application will actually come from SpaceX. They need to figure out fuel manufacturing for a Mars return trip.