We can't turn CO2 back into fuel without an input of energy, but we can store CO2 for the long term without turning it back into fuel. For example, we can pump

We can't turn CO2 back into fuel without an input of energy, but we can store CO2 for the long term without turning it back into fuel. For example, we can pump it into deep basalt formations, where it will turn into rock. And of course when we do want to turn CO2 into hydrocarbons we can use solar and nuclear energy sources, in which case the hydrocarbons play the role of a battery rather than primary energy source. We can also use non-fossil energy to concentrate CO2 from the air; in theory at least that takes quite a bit less energy than hydrocarbons release when burned.