The Future of Energy Storage

Lithium-ion won't work for a lot of things. It would be too expensive. Now you've got a problem to solve. What do you do? Look at everything under the sun that might be able to do it. The one that really jumped out at us was thermal energy storage. We're going to spend the whole rest of the time on thermal energy storage, but you rattled off a bunch of other energy storage technologies that are in use in various places or people are trying.