the fact that using current solar energy may reduce future stored solar energy

Well! The fact is that all coal reserves were laid down before fungii evolved. So there won't be any coal in the future, because trees rot by the mycological vector now.

Oil maybe OK because it was made in anaerobic conditions (bacteria of that persuasion), and we may not have enough oxygen in future. Though that supposes the human race can survive the 200 million or so year for it to be made.

It is all solar energy (nuclear excepted), hydro, wind, PV. All driven by insolation. And several hydro schemes are less eco than coal. EG Brazil, because they have drowned rain forest that should be soaking up CO₂ and is now releasing CO₂ from the rotting trees submerged.

There are many experiments going on to tame nuclear fusion, the US one with multi megawatt lasers has just about produced more energy than that put in, for seconds!

And, recently reported in the New Scientist, there are several cold fusion experiments going on, which the US military are keen to make work. But it may be some time. Particularly since a dubious claim it had been found was never replicated.