Really neat idea. Being able to avoid having to amass gobs of any particular material is tempting. These can be made of anything that can survive compression, and boy do we have a lot of ways of making materials strong.<p>I feel like there's two complications. First, the things as probably super positively boyant, if there's 70 bar / 750m of depth around them & a vaccum inside. Keeping them down seems difficult. I don't think of concrete as super dense.<p>The second problem I see is that they tend to work well at certain depths (can store more power deeper, up to their design limits, where they burst). This causes a bunch of sub-problems. The ocean has a lot of big drop offs- off the FL & GA coast is the Blake Plateau, at 500m, but there's a huge cliff down to the 1500m that is the Hatteras Plain: there simply isn't 750m of depth one can mount onto.<p>The desire to pick good depths also complicates tying this system to wind power. I don't think wind power tends to be installed at such depth. This doesn't change the wind generator much, but it does mean that instead of being able to dump high-amp power from wind-mill to your storage, now the two are separated. And so you have to run lines to the storage, and more critically, the storage system needs a powerful bi-converter to both sink and source power with. I suppose some extra energy conversion isn't a huge factor, but this isn't the nice on-site elegant solution I at first thought it might be.<p>In spite of these constraints, this still sounds like a great idea, full of lots of potential. I love the idea of power storage via physical means, not chemical. This one feels like it perhaps scale to gargantuan sizes quite possibly.<p>Side note, I spent a while looking for bathymetry maps online. <a href="https://www.arcgis.com/home/webmap/viewer.html?webmap=5ae9e138a17842688b0b79283a4353f6" rel="nofollow">https://www.arcgis.com/home/webmap/viewer.html?webmap=5ae9e1...</a> was one of the only ones I found that had any readouts. Google Earth has a map but you have to read the scale, & the difference between 0m, 250m, and 500m is like a 2% shift in color value.
I do not understand, how must these tanks be "underwater"?
You can dig a deep hole anywhere and store energy by emptying and filling it with water.