Comment Re:The grid needs storage - not battery storage (Score 2) 334
I rather like this one, a thermal storage solution.
Note that they don't tell you what the efficiency or capacity are. As you store more power, they lose more energy. Fairly worthless. It also incorporates a special and expensive engine. Fail, fail.
Putting air into and out of bladders under deep water is a very simple method,
No, no it isn't. First, air-based storage is always horribly lossy due to loss of the thermal energy; your above example tries to solve this with technology and argon, but it is thus complex and runs at high pressures and will be prone to failure. Second, the bladders will have to be replaced regularly, because under deep water is not a comfortable environment for them.
as is moving water up and down hills.
The efficiency is not great, but it's a lot better than anything based on compressing gases.
Then there are flywheels and fixed volume compressed air storage.
Well, compressed air storage is still stupid, but flywheels are cool, and applicable ones have been around for at least a decade, see Beacon Power. So yay, we found the viable alternative to used batteries! That took a really long time.
The truth is that used batteries are an excellent way to add more storage capacity, since they're just lying around anyway.