For centuries, humanity has been consuming energy much faster than it accumulates on Earth.
That's not sustainable.
Some estimates indicate more than half the extractable oil in Earth is already gone.

So now the challenge is; what's the best way to harvest / capture energy real-time.
Hydro-electric is pretty good. But it's not perfect. For one thing, there probably isn't enough hydro-electric potential to satisfy the energy demands of a 6,000,000,000+ human population.

I heat my home mostly with firewood.
That's not bad.

If an acre of pond producing algae fuel produces more BTU's per year than an acre of forest, dandy!

Whatever works best.

"when the bigots of this world have been privileged for as long as they have, to them equality feels like discrimination." shiftless2