And it gums up your engine more than gasoline does. Although this problem can be mitigated somewhat.

It's the opposite – it's gasoline that causes carbon deposits on the engine, and ethanol acts as a detergent.

Methanol also works, and doesn't compete with food production. You can make ethanol catalytically if you want, but you have to make methanol first.

Ethanol has some issues:

- If large areas are deforested for sugar cane plantation, not only CO2 is released but the capacity of fixing future CO2 as well. - Large scale sugar cane plantations demand synthetic fertilisers, which come from fossil fuels. - Ethanol burning still produces toxic gases like NOX.

Can you make ethanol from thin air, such as with the Sabatier reaction? I like the fact that you can take electrical energy input, atmosphere, and get methane. This means I could convert excess solar into a mass and volume dense combustible, and then retrieve some of the store energy back later.

Personally I'm principally nerding out about energy storage for sailing cruising yachts. But I have by no means done an exhaustive search of the space.