... and something we might be able to fabricate, at least as a mock-up, in Physics and Renewable Energy classes.
A good way to teach the Laws of Gravity and Thermodynamics, and some small-scale mechanics and fabrication.
If you want to sponsor these guys to get to their beta test, the link is here.
(But it seems like they have the cash they need -- for now. I expect they will need more to scale up.)