[pfdietz]

Absolutely. Hydrogen can be stored underground for maybe $1/kWh of storage capacity. There would also be power related costs, but those don't matter nearly as much for rare event backup.

Germany alone has the potential to store an estimated 9.6 PWh of hydrogen, enough to supply their average electric power demand for years, not weeks.

https://www.sciencedirect.com/science/article/abs/pii/S03603...

[modo_mario]

Creating hydrogen with excess power is really inefficient energy wise and also tips the scales of cost a lot.

[pfdietz]

Only a fraction of the renewable output would have to be routed through hydrogen, though. It turns out this is still cheaper than new nuclear for providing "synthetic baseload" supply, especially if one looks at projections of how much renewables should cost in the time it would take for any new nuclear plant initiated today to come online.

[p_l]

Said "fraction", for moderately modest needs and assuming just 24h window where it provides "baseload" can be as "low" as 1/3rd of total renewable capacity - assuming that renewables do 100% of peak whiel saving the excess..

Or so analysis from people I know in the industry, interested in decarbonising (not fossil lobby related), show.

[pfdietz]

Sounds about right. See https://model.energy/ for a toy model that gives about that number, when you solve the optimization problem for Germany. The optimal solutions still have some renewable curtailment, though.

[p_l]

Trying to get usable values for Warsaw area, it gives me the result that we need 8x overbuilding (curiously it suggests solar power mostly), and I'm not sure if we could decarbonize heating on that.

[pfdietz]

Poland is one of the worst places on Earth for renewables. If nuclear still has a shot, it's around there.

[dageshi]

If the energy is basically free which under certain circumstances (lots of wind) could happen, does it matter how inefficient it is?

[rualca]

> If the energy is basically free which under certain circumstances (lots of wind) could happen, does it matter how inefficient it is?

There are two sides to this cost: energy production, and storage.

The part which is argued to be essentially free is the production, which is not synchronized with energy consumption patterns.

Renewable's main challenge is how to store energy cheaply in order to be able to be used reliably to supply the baseline. Until that happens, everyone is required to employ non-renewable energy sources that can and do meet the baseline.

It matters nothing is production is free if storing it to supply the baseline is more expensive and thus wasteful than conventional non-renewable sources.

[ben_w]

Depends how expensive the electrolyser is. Just because I did make something when I was 9 years old that could fill up a small jamjar with hydrogen, doesn’t necessarily mean it’s economically viable.

(I have no idea either way if this is an important limit or not. Just that it can have other sources of downside besides merely using otherwise wasted energy).

[pfdietz]

There have been reports of cheap mediocre efficiency alkaline electrolyzers in China for under $200/kW. This is indeed a key area for hydrogen from intermittent renewables to be successful, but I think there's great room for cost decline here as volume ramps up.

[thrill]

The creation of the hydrogen is only a portion of the overall system cost, which may total cheaper than alternatives.