What si the single most significant barrier to widespread use of alternative energy? Is it the right wing climate change skeptics? No. It’s economics. If there is not money to be made at the same scale as in the fossil fuel industry, and if renewable, clean energy does not become cheaper than fossil fuels, alternative energy doesn’t stand a chance in the free market.
As technology moves often faster than society, politics, culture, etc., the economics of alternative energy look brighter and brighter.