[pfdietz]

Not really. NPPs as backup to wind would be horribly expensive. Wind droughts don't happen often; even the current price during them would not make a NPP pay off.

What would make sense is larger local stores of hydrogen, to be burned in combustion turbines during the rare wind outages.

[Manuel_D]

Are there any commercial operators of electric grid storage using hydrogen? I can only find prototype or demonstration projects.

Most of the time, people saying grid-scale storage is feasible point to technologies that exist in the prototyping phase. The reality is that we don't know whether these solutions will be feasible at scale, or if they'll hit bottlenecks or poor scalability that drives up cost when deployed at scale. Comparing a hypothetical cost of hydrogen, to actual historical cost is comparing apples to oranges.

[pfdietz]

Why should any exist yet, when natural gas has been so cheap? Tighten the screws enough to eliminate fossil fuel dispatchable sources and you'll start to see it (or something else that can solve the same problem better).

[Manuel_D]

Many places are already seeing energy surpluses. California and Hawaii are consistently reaching excess daytime energy production. If we really can store electricity in hydrogen $1/KWh, then we should be seeing hydrogen storage being built to profit off these intervals of negative energy prices. But we aren't. Is it because people fail to see this market opportunity? Or, maybe, it's because writing a white paper claiming an extremely cheap cost is not remotely the same thing as actually building an energy storage facility at said cost.

I agree, we should tighten screws to eliminate fossil fuels. But hydroelectricity is the only scalable form of grid storage we currently have, and that's limited to the right geography. Expecting some unproven technology to be a silver bullet for storage is extremely wishful thinking. We need to be honest about technologies like hydrogen, compressed air, flywheels, etc: These are experimental technologies that might operate cheaply at scale, but we have no real-world experience to back up these claims. I could just say "storage is irrelevant because fusion will deliver energy at $1/MWh" and while nobody can technically disprove it, since they can't see into the future, it's also dishonest to claim this as fact for the same reason.

[pfdietz]

Natural gas is really hard to displace here, and won't happen until it becomes and stays expensive. It may now be above that price level in Europe, but it has to stay there to enable the capital investment in large scale green hydrogen production.

[Manuel_D]

Yet the condition you claim will give rise to widespread adoption of energy storage already exist in Hawaii: fossil fuels have to be imported making it expensive, and daytime energy prices regularly go negative due to widespread solar adopt. These conditions have existed for years. Yet people aren't storing and reselling this energy. Why not? If hydrogen storage really costs only $1/KWh then a company can reclaim their investment cost in less than a week of operation, with an average price of $0.30/KWh in the state. It's basically free money.

The reality is that hydrogen storage costs nowhere near $1/KWh. People making predictions about what a technology will cost and actually building it are two totally different things.

[pfdietz]

That storage cost is in salt formations, a technology that is already widely used to store megatons of natural gas. A single salt formation in Delta, Utah could store enough hydrogen to supply the entire US average grid power for 30 hours (and efforts to exploit this formation for hydrogen storage are ongoing). Salt formations exist in ample supply in Germany and Europe, but there are none in Hawaii, which is entirely volcanic.

[Hypx_]

It's actually closer to $0.10/kWh, but we have to account for the cost of upgrades to the infrastructure.

[p_l]

Scaling is also hard... Turns out you need more than "trickle" overproduction to make reliable amounts of green hydrogen for energy storage.

[ephbit]

Hydrogen is relatively inconventient/difficult to handle except when transported via pipeline.

There appear to be no dense long range pipeline networks (for hydrogen) connecting multiple countries (yet).

Pipeline networks for natural gas aren't designed to safely transport pure (or high concentrations of) hydrogen, so over a certain concentration hydrogen would have to be converted into synthetic natural gas. The latter conversion appears to not yet be deployed at very large scales.

Seems to me that the reason why there is no large scale hydrogen generation yet (though there are medium-large/industrial scale projects now), is simply that until now large scale wasn't economically feasible. With hydrogen strategies and more pressure from a price on CO2 on their way we'll definitely see more of it soon.

[pfdietz]

For grid storage, hydrogen would not need to be transported at all (although the option to do so is there if it's favorable). It could be made above the storage caverns, pumped into them, then extracted and consumed there.

[FartyMcFarter]

> What would make sense is larger local stores of hydrogen, to be burned in combustion turbines during the rare wind outages.

Would this work when there's little wind for a week or more?

[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.

[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.

[xxpor]

We should probably prefer pumped hydro before stored h2.

[chess_buster]

Molten Salts powering the old coal plants in a closed system.

[pfdietz]

Hot sand looks even better (much higher storage temperature):

https://arpa-e.energy.gov/sites/default/files/2021-03/07%20D...