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Comment by IfOnlyYouKnew | Hacker News Reader

You’re obviously trolling, but to explain it to those possibly baffled by your professed ignorance: a large grid is indeed a commonly-accepted mechanism to store local maxima of wind or solar production. As you connect more regions, father apart, simple statistics lead to averaging out of individual spikes.

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Actually, it's not just a matter of averages, but also of availability of actual storage capacity as well as other loads that can adapt to availability. Mind you that you can store energy in more forms than what can easily be converted back into electricity. Cooled warehouses, to take a random example, in many cases can cool down a few degrees further than required when there is plenty of energy available, and then avoid using electricity during peak load times. If you can use all the warehouses on the continent to drop some load off the network when production drops unexpectedly in some region, that makes things much more stable than if you only have the capacities within one country at your disposal.

On this same topic, of course the big issue with wind and solar is that they don't generate if it is not sunny or windy. This means we still need base power generation with fossil fuels or fission. However, wind is stochastic enough that on a large grid, around 1/6 of its maximum capacity can be counted as base power.

With a sufficiently large grid, it's always windy somewhere.

Solar-thermal plants can produce electricity over night. We could for example build a bunch of solar thermal in the Sahara and connect Europe via HVDC lines.

Solar thermal is still several times more expensive that PVs, and I'd kind of have trouble seeing how that could come down massively in the same way that PV price has.

How much more expensive that PV+equivalent storage is it?

I suppose it depends on the storage. The first full-scale CSP in the US is Crescent Dunes in Nevada, but it cost $975 million and has a rated capacity of only 175 MW. At this point, I wonder if it would make more sense to just use PV with molten salt as storage heated with resistive heating.

Nope, you need peaking not base load power.

Base load refers to lowest cost per kWh sources that fail to meet the demand curve. That actually describes wind and solar very well.

PS: Wind + coal don’t work well together. You end up turning off the coal plant fairly frequently which is bad for the systems and eases cost per kWh.

Hard coal plants do a lot of load following in Germany, especially when it's windy.

For example the black in these charts is hard coal and the green is wind.

https://www.energy-charts.de/power_de.htm?source=all-sources...

Guess I got my terminology wrong, but I meant sort of base steady power capacity in the way that fossil fuel plants are. Yeah, I know coal doesn't spin up and down well, but gas does.

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