That doesn't mean it's a bad idea but they are factors that add to the overall cost. 20$/kwh is very attractive of course. But that's also a number that e.g. CATL is chasing with sodium ion batteries. And they are going to be making those by the gwh/year from next month.
How many big cities are there on earth with that depth available nearby?
https://en.wikipedia.org/wiki/Project_Natick
Or it could help offshore wind farms provide a more stable/predictable output.
Almost the entire Mediterranean is >500m depth within just a few km of the shore, and that's half a billion people. All of the eastern seaboard of the North+South American continent is available at 100km distance (another 100-200mn people). Most of west Africa, all of Australia, and almost all of the western flank of the Pacific.
Maybe a quarter of all people live within 40-50km of a 500m deep sea. Definitely a large TAM.
[Company] has tested a small model of the reservoirs in wave tanks and off the coast of Reggio Calabria, Italy. It’s now deploying a pilot of the floating components in advance of a full demonstration plant. By 2026, it’s hoping to deploy several commercial projects at sites around the world.
At full size, the turbines would generate around 6 to 7 megawatts of electricity each, and there will be one for every 100 meters of pipe. Deeper sites would have more storage potential, and each commercial site would host multiple reservoirs. Sizable hopes to deliver energy storage for €20 per kilowatt-hour (about $23), about one-tenth what a grid-scale battery costs. —-
Testing in calm reservoire is different from potentially .wild offshore (ocean/sea)
What happens to 100-200 m long pipe in underwater waves when e.g. a hurricane or a storm comes?
The bigger issue with this idea is that it's a megastructure sitting in the ocean, and salt water turns everything it touches into shit. Oh, and there's very little energy storage potential from just a salt gradient. You need to move way more water, to get less energy, but your container costs are fixed.
Land-based pumped hydro has no shortage of engineering problems (and risks if, you know, you get a dam collapse), but this has colossal capex costs.
Nothing, to a rounding error. The effects of surface storms are only noticeable to ~2x wave amplitude.
There are plenty of other forces at work, especially tides, but storms will only affect the surface plant.
That’s an excellent question, but it is also similar to asking what will happen to wind turbines in a storm.
Maybe some will break. Maybe that’s an acceptable outcome. Probably they can be improved to reduce that risk
I don't think the Journalist who wrote the article understood the technical details, but from digging a little at their website I think what's going on is they're moving heavy brine up and down, all of it equalized with local pressure.
Despite them describing it as pumped hydro, I think its better framed as a cousin of the "chunk of concrete suspended over a mine shaft" style gravity battery. Replace the mineshaft with water and the concrete with salt.
On each of these kWh you'll have (hopefully) multiple orders of magnitude of charge cycles
Battery capacity and energy consumption are measured in the same unit.
https://www.renogy.com/blogs/buyers-guide/how-much-does-a-li...
Otherwise I love the fact that's simple. Simplicity scales. It's also salt water, so assuming they're not putting anything else than NaCl, it can break and it's no big deal
Mentions of efficiency are conspicuously absent from the article.
Another potential problem is marine ecology: pumping high-salt sea water to the top and releasing it en masse might lead to much larger fluctuations in salt concentration than what the ecosystem is used to.
That said, we need many different approaches to solve energy storage, and I hope to be wrong, and that they end up very successful.
The advantage I see for the salinity difference is that you can make them a lot larger than the pumped water ones. But is worth it, I'm skeptical.
foota•2h ago
robertlagrant•1h ago
The "at scale"s might be very different between "what would be enough to affect local weather" and "what would store all the excess electricity generated in non-peak hours".