[martinald]

You are missing one point though, that the cost of non-renewable energy goes up when there is no renewable energy in the grid often very significantly.

Effectively renewables have an externality cost of their own: they make "reliable" sources of power much more expensive.

Imagine that wind/solar power supplies 25% of the grid's needs - this means 75% of the time you need a gas power station to fill in the lulls in production. Fine.

Then imagine you triple the amount of renewable energy on the grid to 75%. The gas plant is now only operational 25% of the time, but still requires capital cost of construction and maintenance to be ready to go. Ok, it doesn't need as much fuel but apart from that you have tripled the cost of the plant.

So the problem is that it becomes uneconomic to build the electricity generation that stabilises the grid and makes it possible to have any renewables in the first place.

We're now seeing huge premiums being paid to companies by the various electricity grid operators to cover this problem. This then goes on ratepayers bills to cover "distribution" or "grid reliability". And it then turns out your $0.03/kWh wind is not actually that at all and gets more distorted as more wind gets generated.

We need better energy storage options before renewables really will fulfill their promise.

[philipkglass]

I didn't mention effects of 75% grid supply from wind + solar because no major grid is operating at that level. Most grids are significantly below 25%. The US as a whole is currently at 5-6% of all electricity consumption from wind + solar. (I know there's not a single unified grid across the US, but still.) I expect that storage is going to be significantly more mature by the time the US reaches even 25%.