In general, from my own efforts to try to understand the answer to that question, pumped hydro storage is probably the most promising but it'll only work in places that have the geography for it. There are a couple of excellent examples in Scotland, https://en.wikipedia.org/wiki/Cruachan_Power_Station is one. The trick is that there's a 400m drop; lots of places won't have the geography to get that much head.
In Germany? So far it has been mostly magical thinking. It has almost infinite capacity
Realistically, long-term hydrogen storage is the only technology that is even remotely feasible. There are several demonstrator projects ongoing right now. I'm personally not too optimistic about them.
Germany has been the biggest exporter of electricity in the world in 8 of the last 10 years. Germany also has one of the most reliable grids in the world in terms of system interruptions - as measured by SAIDI - with less than 15 minutes of interruption per customer year - significantly more reliable than France for example. They've managed to keep the lights on after going completely cold turkey on Russian gas in the space of less than a year - a remarkable feat which has been given no credit by most German energy policy critics who have been confidently predicting energy Armageddon in such a scenario.
Not to say that there are no grounds for criticizing German policy but most of the criticism seems to be politically motivated rather than based on specific failures of the policy.
Secondly, why hydrogen? It's a potent greenhouse gas - GWP100 of 12 or 13 times that of CO2. Yes it's less potent than methane but it's far "leakier" and more difficult to contain than methane as well as being more dangerous and difficult to handle. It cannot be combusted in air (most are suggesting mixing it with methane) in a domestic setting because of the 10 times as much NOx caused by the higher burning temperature. While all the infrastructure for methane/natural gas already exists including long term (seasonal) storage facilities, I see no compelling reason to spend 100s of billions to build all this new infrastructure to use a different warming gas for energy storage and transport.
To be honest it's a minor issue in the grand scheme of things - keeping natural gas around to cover the last 10% of electricity generation is no big deal as the world rushes to electrify the other activities which currently release large amounts of CO2. The focus should be on getting to that 80-90% carbon-free electricity and the electrification of as much as is possible of pollution sources like domestic heating/cooking, transport and heavy industry.
> Germany has been the biggest exporter of electricity in the world in 8 of the last 10 years.
Sure. The good old coal power plants and natgas turbines are extremely reliable and capable.
As for Germany being an exporter, Sweden and Norway both have recently declined to expand their interconnects with Germany. They don't want their local markets to be swamped by cheap low-quality power during the summer, and then squeezed during the winter when German renewables are greatly diminished.
> Not to say that there are no grounds for criticizing German policy but most of the criticism seems to be politically motivated rather than based on specific failures of the policy.
The specific failure of the policy is simple. Germany's power is DIRTY. And it's not getting any better.
> Secondly, why hydrogen?
Because there are no alternatives. Power-to-methane is going to be about 3-4 times more expensive than pure hydrogen. And again, this is not my personal preference, but the official policy of the German state.
> To be honest it's a minor issue in the grand scheme of things - keeping natural gas around to cover the last 10% of electricity
It won't be 10%, more likely 30% once Germany switches to electric heating and EVs. This switch right now is being held back by horribly high energy cost.
It’s difficult to respond to someone who claims that “Sweden and Norway both have recently declined to expand their interconnects with Germany. They don't want their local markets to be swamped by cheap low-quality power during the summer,”
Elections carrying electricity do not have the quality of being “cheap” or “low quality”. If you’re convinced that there is some measurable difference between an electron produced by a hydro-power turbine and one from a coal plant, then I don’t think we have any basis for further discussion.
> Elections carrying electricity do not have the quality of being “cheap” or “low quality”.
They do. Because electrons, that are forced to move by the wind, cease moving when there's no wind. And this happens for weeks at a time in winter in Germany.
There's a fix for that: capacity markets. In essence, if you can guarantee that your source of electrons will always be available, you get paid for that. Europe has pledged to "do something" about that EU-wide by 2028.
