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Comment by asdefghyk | Hacker News Reader

What happens when there is wide bad weather for renewables? ( for a range of days from 1 - several) Where would the power needed come from?

If, it was to be from some kind of storage, Extra capacity would be needed to allow recharging of the storage

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Wind and solar power are remarkably stable in Europe. Last year, the average weekly electricity output was 14.0TWh; not a single week fell below 10.5 TWh.

Weather fronts move across the continent on a very regular basis; when the wind dies down, the sun shines more.

Surely global warming is going to lead to a less stable environment going forward?

Mind that nuclear power relies on favorable weather as well. It's not uncommon in Europe that nuclear power plants have to shut down, because the rivers they use for cooling become too hot.

Not quite. It's done to save fish. And it's not fixed because France is already maxing exports in the same period

Bad weather often comes with wind or rain.

Obviously it’s possible for solar, hydro and wind farms to stop producing, but that’s what storage is for.

Not really. Storage is most used for short term stabilization and alleviating congestion in certain transmission nodes. In most markets its used to provide capacity under contract with utilities to meet resource adequacy requirements which don’t consider long term regional complete loss of renewables. Longer term storage that can provide power to, say, a whole region during a multi-day storm is basically an uneconomic fantasy that rational developers have no real incentive to build, because it would be a huge overbuild most of the time, and accordingly undercompensated for said overbuild. Developers are building batteries that are just the right size for a capacity contract & providing ancillary services (voltage support, frequency regulation, etc) plus price arbitrage, which are deployed for only minutes to a few hours. There are some 8 hour duration batteries out there, but they are not common.

Multiday renewable droughts ( solar and wind ) are a significant challenge. ( A further problem would be if a renewables drought occurred at a (multiday) peak demand period ) Appropriate (often new) wide area, power transmission networks can help to reduce this risk. Renewables also need to be over provisioned to reduce the risks, which could be blackouts or some kind of power rationing (via "smart meters" )

ideally power rationing is not needed thanks to the electricity market - and you could still perform an intentional brown out to avoid a black out

The specific battery I had in mind was hydro.

New Zealand is contemplating a large project (didn’t think we into infrastructure any more) which is considerably more capacity than a few hours.

https://newsroom.co.nz/2025/10/17/the-lake-onslow-pumped-hyd...

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