You're thinking entirely replacing our energy source. What about just boosting it passively. Imagine if energy requirements for every human were decreased by 2%
There's other possible fixes too. For starters, Vitamin D?
Taking the spherical human to require 8400 kJ/day, we're talking ~170 kJ replacement, or:
~6g butter, or
~1/3 of a can of Coke, or
~1/3 of a single Bounty piece, or
~1 McNugget (without sauce)
on an environmental perspective, if applied to everyone, its almost half a quadrillion kJ removed a year, plus supply chain logistics, waste, packaging,
I still think its probably a ridiculous pipedream, but even pipedreams are meant to be dreamt.
Otherwise known as an American? ;)