DC Desalination - The idea

There are many corners of the world that have access to abundant seawater but where potable water is expensive. Some of those places are also affluent like the cities of Los Angeles and San Diego in California and several cities in the Middle East and southeast Asia. The key to this idea is to find a way of doing desalination that doesn’t require getting the salt water warmer than 80 degrees centigrade because data center processors have a much shorter lifespan above that temperature. That temperature rules out boiling the seawater as well as concentrating it over a series of flash boilers. Thankfully, there is a solution, and that is Multi-effect distillation (MED). Instead of just evaporating water and letting it go into the atmosphere, MED captures the pure water in the form of steam and condenses the drinking water back into its liquid form (while heating up more saltwater). Most MEDs are typically run below 70° C, so we don’t need to worry about overheating the processors. If you know some thermodynamics, MED may sound like magic. If you take room temperature salt water and boil it to get pure water steam, it requires a lot of energy and the heat source must be above 100° C. One of the keys to MED is that the final product that you want is room temperature drinking water, not steam. So, you can use the heat from the steam to heat more saltwater. Theoretically, the only energy lost is from the differential heat of vaporization between pure water and salt water and the pumping energy, which isn’t much compared to the heat of vaporization. It’s possible to be ten or more times more energy efficient than just boiling the salt water.