The only plausible near-term renewable-energy flight option I can see is hydrogen fuel cells powering electric planes. The equipment is heavy, but compressed l

The only plausible near-term renewable-energy flight option I can see is hydrogen fuel cells powering electric planes. The equipment is heavy, but compressed liquid hydrogen is both producible from renewable sources and has a significantly higher energy/weight ratio than traditional fuel. It would require a few advances in fuel cell technology, but that's totally plausible.