Comment by xyzzyz | Hacker News Reader

Comment by xyzzyz | Hacker News Reader

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Renewables are cheap per kWh, but they are only intermittently available, and since storage is basically nonexistent at grid scale, these kWh are only worth anything if there is demand for them, and are useless when there is demand, but sun is not shining or wind is not blowing. In effect, you still need to have some other way to produce electricity on demand, when there is no renewable supply. What’s worse is that if these more flexible sources of electricity (typically coal or gas) cannot compete with renewables when they do produce, they need to charge much more when renewables are out, in order to stay profitable — otherwise, they’d close, and we’d wouldn’t be able to meet the demand at all times. This would result in customers getting disconnected with very little notice, making them very unhappy.

To sum up, it’s more expensive, because even as renewables grow in installed capacity, we cannot reduce installed capacity of fossil sources on 1-1 parity, and also we pay more per fossil generated kWh than we used to in all-fossil grid. Cheap grid-scale storage would solve this, but it’s no going to happen any time soon.

Thanks! Hopefully that means that, if renewables keep getting cheaper, then the economics will keep getting better.

Not really, unless we can figure out how to make sun shine or wind blow 24/7. The intermittency is fundamental problem of solar and wind, and unless we figure out cheap storage, prices of electricity will not go down.

But if the price keeps falling for electricity generation, isn’t there some sort of break-even point where you overcome the increased distribution costs?

If the sun isn't shining and there isn't sufficient buffered storage (batteries, etc) then even if the solar panels are a penny each, their kwh costs are infinite until the sun shines again.

If you can cover 95% of the time but still need a natural gas power plant for the last 5%, you haven't saved any money except the cost of the natural gas itself. In the US, it is stupid cheap, so you haven't saved much at all.

This is not about distribution. When sun is not shining, there is no solar energy to distribute. You can build as much solar as you want, but you won’t get any electricity from it during the night. Peak demand, however, is right after sunset, and only slowly peters out until midnight. Where are you going to get energy during that time? If you build enough wind all across the country, so that it is by itself enough to cover the peak demand even during low wind conditions, then it could work — but it’s cost prohibitive, and you wouldn’t then build any solar anyway (if wind was enough to cover peak demand in the evening, it would also be enough to cover demand during the day, no solar necessary).

In practice, until cheap storage is invented, and as long as nuclear energy is eschewed, renewables will be paired up with fossil, and prices will stay up.

Cheap storage is already invented, many times over. But it needs to be built out. That is delayed in part because prices are falling so fast; waiting means you get it cheaper. But most storage techs are very cheap or free to operate, so any built today will stay in use.

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