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Comment by Brakenshire | Hacker News Reader

Has anyone seen any good explanations or visualisations of how long term storage would be achieved? For instance in Britain solar in winter has 1/10th of the output in summer, and we can have lulls in wind output for many days at a time. Using these resources to reduce gas use makes sense, but our current plans call for about 30% of electricity generated from gas using carbon capture and storage. How would this be handled under a 100% renewable scenario? Is it just generating Hydrogen?

Or it is that these intermittency gaps can be closed using long distance connectors? Has anyone done studies showing exactly where resources would need to be located and the length of connectors, modelled against weather and demand patterns?

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Yes, long distance transmission for geographical diversity of wind power. This is studied a lot in the power generation industry. Without long distance transmission you need natural gas peaker plants capable of the same output as solar/wind, and solar/wind is more expensive than just building natural gas plants (but less CO2). We cant build enough batteries to use in place of peaker plants until sodium batteries are production ready and produced at large scale (this could happen by the end of the decade though).

Hydrogen for short term storage, ammonia for medium term storage. Both much less efficient than just using electricity directly, but the aim is to drive down the cost of generation so that the inefficiency doesn’t matter so much.

There are also tons of other short-medium term storage solutions, and we probably need all of them that we can get our hands on, but hydrogen and ammonia are the ones that feel most likely to operate at grid scale.

Hydrogen is not for short term storage. In short term storage, efficiency becomes important, and the round trip efficiency of hydrogen isn't great.

https://www.wartsila.com/energy/towards-100-renewable-energy...

Suggests Great Britain would ideally have only 1% solar, and storing 8% of the wind production as Green Hydrogen

Doing it without Green Hydrogen, just solar wind batteries would double the cost.

Connectors help too, though they also cost money to build. As renewables and batteries have plummeted in price, connectors have become less necessary. Once you have Green Hydrogen you can ship it around and store it like LNG.

Pumped hydro and hot sand batteries should be enough if we get our act together and actually commit to something. There’s also no reason solar from Spain or Morocco couldn’t be wired in at some point. Obviously we currently have a chicken and egg situation where it’s not worth building the X times our peak need in renewables without the storage and not worth building the storage when renewables are a fraction rather than a multiple of our current supply.

The problem with getting electricity from Spain or Morocco (or any other country) during winter is not a technical but a political one. Once a nation energy security depends on an another nation you may end up in situation Germany found herself in

Well I’m pretty sure Morocco becoming as wealthy as Saudi would make it stable enough, one way or another.

> For instance in Britain solar in winter has 1/10th of the output in summer, and we can have lulls in wind output for many days at a time.

Wind has higher output during winter

Wind has higher average output in winter and at night, but even in winter and at night, it has lulls which last for many days. Look at the wind and solar generation numbers for Germany for a month last winter:

https://www.energy-charts.info/charts/power/chart.htm?l=en&c...

If you connect wind production across regions the lulls can be averaged out, but I want to know how reliable that is and what distances are required.

days is already way less than seasonal - and it can't be averaged out entirely even across europe -> storage capacity still needs to be increased when approaching higher shares of renewables across europe

> For instance in Britain solar in winter has 1/10th of the output in summer, and we can have lulls in wind output for many days at a time.

Grid expansion can average over regional lulls. Renewables also need to be built to provide significant overcapacity. Storage can help, but you can do it with only those two.

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