The summer class just covered gravitational potential energy (GPE) and it’s fun to think of ways that GPE is pragmatically useful. Hydroelectric power is in part a way to harness GPE by taking a mass of water that is higher up (behind a dam) and then, in a controlled way, releasing GPE by allowing the water through to lower elevations.
GPE is also being explored as a store of energy when wind and solar energy exceed demand. You see, wind and solar power often go beyond what people need at certain times during a day, and then they end up supplying too little at other times of day (i.e. solar doesn’t produce energy at night). One obvious approach is to develop battery technology that can soak up the excess energy production and then release it back to the energy grid when other power sources are undersupplying. The problem is that we don’t know how to make batteries dense and efficient enough to solve the problem, so people are exploring alternatives, one of which is to use the extra energy to lift very heavy weights high up in the air, which can then be lowered in a manner that causes a generator to turn, thus siphoning off (some of) the GPE back into electrical power. Here’s an article describing some recent work on this: