You have salt water. You heat up the water. Water evaporates off the top, condenses somewhere, the condensed water is clean drinkable fresh water. The stuff that's left is brine, which is essentially a waste product.

The engineering question is how much water do you use? You could use a thick later, like a swimming pool. But that takes a lot of energy to heat up. You could use a thin layer, like an inch thick across a parking lot. This takes less heat energy, but a lot of energy to clear out the brine, and a lot of salt will build up that you will need to periodically need to clean out.

This thingie does the best of both worlds. It is a thin layer at the top. Thin is good, because it takes less energy to heat. The layer between them is insulated, so you don't lose heat energy to the pool of water below it. There are channels between them that transports water upwards and salt downward via convection.

The thin layer at the top heats and evaporates quickly. The salt is transported fairly rapidly past the insulated boundary and into the large pool below. The large pool supplies more water through the same boundary.

The large pool can be slowly mixed with the ocean.

I'm kinda blown away by this. What a shockingly ingeniously simple and effective mechanism. It's like when I learned that the guts of a normal coffee machine that makes coffee machines do coffee machine things is just a heater, a hose, and a one way ball valve, and literally nothing else.

I hope it works and I hope it scales. We could be done with California's drought problem in a decade.

Clean water evaporates from the top like a traditional system.

This innovation simply helps prevent the water where the evaporation is occurring from getting too salty over time.