The answer is likely going to have to be hydrogen, but there's a pretty difficult catch with hydrogen: it makes zero sense to invest in any hydrogen electricity storage infrastructure until the grid is already like 80+% renewable.
There's simply no sense in turning electricity into hydrogen so that it could be used in 6 months (losing 50+% of the energy along the way as heat!) when you could just sell that electricity right now, or stick it in a battery so you can use it 6 hours from now.
There will be an economic case for hydrogen energy storage in Europe in 10 years, but unfortunately the technology is basically sitting at a standstill right now with no attention and no investment because it's not needed yet.
Syngas makes a lot more sense than hydrogen, in the short term. But what really makes sense in the longer term is massively scaled Carnot batteries. Slightly less efficient than batteries, but really cheap to build (it's a combination of resistive heating and old-fashioned thermal power station technology) overbuilding renewables is cheap, and you can charge your Carnot battery [almost] all year long.
I think there's a lot of question marks hanging over a lot of these things. I don't want to sound more confident in hydrogen than I actually am, and I don't want to sound more dismissive of syngas and other long term storage options than I really am. I'm really just not sure at the end of the day.
Another option that I think is under-discussed is just seasonal storage of biogas. Germany currently derives around 10% of total electricity production on any given day from the burning of biogas. If we could replace all of that daily usage with renewables + batteries, then we could potentially just save up all that biogas in reservoirs and burn it during periods of low renewable output. No new technology, and very minor new infrastructure needed.
It's hopeless to scale biogas production up to a point where it provides for the whole grid, but it might just be enough to deal with week-to-month scale renewable shortfalls.
even in 10y h2 is economically unviable. Check out Norway/Sweden, they got tons of ren. Are they some _cheap_ H2 generation meccas? There are some chances for other synth fuels but H2 is just a pipedream
Norway and Sweden have tones of renewable energy, but relatively little intermittent energy. If the economics of H2 ever work, it'll only ever work in a grid that's driven by intermittent energy sources (wind and solar).
A hydro-driven grid does not need storage. Hell, if you have enough hydro, it can even be your storage. Not all of Europe has the geography to be able to cover their needs with just hydro.
H2 economics work if you have constant oversupply. If your electrolyzer works only 50% of the time and storing is expensive, transporting is expensive and roundtrip efficiency is abysmal, it'll still cost a ton. Higher chances to use just cheaper gas generation because even LNG is cheaper than H2 saga.
H2 economics don't work at all, and H2 is largely a fig-leaf for the fossil fuel industry.
If you were to have an environment in which H2 would actually make economic sense, non-H2 storage and distribution systems would be even cheaper, and they can be added incrementally rather than needing a big bang, preventing investing in H2 from taking off in the first place.
Not a constant oversupply because then you'd never need the hydrogen in the first place. H2 economics (if they ever work) will work in a place where there's a seasonal gradient in energy production that's over too long a time horizon for batteries.
Per lazard, currently, merely 25% green H2 peakers would provide power for as expensive as worst nuclear project in US- Vogtle. So a mere 1/4 mix is as bad as a terribly mismanaged construction project. H2 economics for electricity are non existent. It will be used fo other sectors maybe, like fertilizers
Look, I don't really want to be in the position of defending H2 here as I'm not particularly confident or optimistic about it, but I'm not really currently seeing a better alternative for seasonal energy shifting.
If Germany was willing to build new nuclear power plants I'd be potentially in favour, but it's not going to to happen, so H2 will likely be the way, and it won't be cheap.
That said, I also invite you to go look at cost estimates for batteries from just 5 years ago and compare them to today, or solar / wind cost estimates from 15 years ago. Those technologies have experienced significant reductions in cost due to scale and industrial learning.
IMO the biggest problem with H2 is that similar sorts of learning / scaling processes simply won't even start until the grid evolves to a point where the seasonal demand shifting is actually required, but by then it's essentially too late. And there's not really any hope of governments kickstarting the learning process with artificial demand because people will make all sorts convincing arguments for why it's a stupid waste.
So I guess we'll see what happens. Perhaps stuff like fertilizer and steel will help the technology matures before the grid needs it, or perhaps battery technology will surprise us again, or someone will figure out how to make flow batteries work or whatever. I'm not particularly confident in any of these technologies, but we'll just have to wait and see what happens I guess.
Something *does* need to be done about storage though, even with all the complementary wind-solar and giant Lithium or Sodium battery installations, and all the HVDC you could want.
There's simply no sense in turning electricity into hydrogen so that it could be used in 6 months (losing 50+% of the energy along the way as heat!) when you could just sell that electricity right now, or stick it in a battery so you can use it 6 hours from now.
There will be an economic case for hydrogen energy storage in Europe in 10 years, but unfortunately the technology is basically sitting at a standstill right now with no attention and no investment because it's not needed yet.