I found a large cavern under my lunar homestead. It is several hundred feet (a couple hundred meters) deep and fairly large. There is a large ice deposit at the bottom. I am able to warm it to temperatures that will keep water liquid through the day/night cycle.
Knowing that lunar day/night cycle is 29.5 Earth day I have half that time when I can collect solar energy, and half that time I will need to rely on stored energy.
On Earth water is used to power things, sometimes a river is dammed for hydroelectric power, in other cases Electrolysis is used to create fuels like Oxyhydrogen. Ultimately all these sources of power are rooted in solar energy.
I have some different options for storing the solar energy from the lunar day in water.
- I can use a pump to elevate the water to the top of the cavern. At night I let the water fall through a turbine and generate electricity.
- I can use Electrolysis and separate the H and the O then burn them to create heat make steam to turn a turbine and generate electricity.
There are several combinations and probably some options I have not considered.
Assume I need all my energy returned as electricity, not as mechanical energy (i.e. I am not using a water wheel to mechanically power my air purifier)
With current/modern technology circa 2020 how can I most efficiently store and recover solar energy in water on the moon?