wondering about desalinization of seawater....?

Question

at what temperature does ocean water turn to water vapor and clouds?.... I'm guessing it's quite a bit below boiling, as seems to be necessary in a 'still' to get the steam to become 'fresh' water..... so.... could we kill a couple of these birds by something like this?.... running salt water thru black pipes to warm up in the sunlight, maybe in the same place as the solar collectors for elec power?, then out to holding ponds with plastic over them for the condensate to collect and run off....moved by pumps powered by windmill turbines? seems like this would work good in the desert... hot days, cool nights for the condenseate to work?.... of course, we'd have to pump it from sea to desert, right?... same windmills?....

I'm prob pretty far out, but there's gotta be a way for us to get that water made useful to those who need it!!... got any other ideas out there?....

thanks, you two, for indulging me and my outlandish ideers.... I'm glad someone else is tossing ideas around, tho.... this seems like one of the most important problems just now.. I hope it's soon solved...

Answer 1

That is one idea. I´ve been thinking about a glass structure. Maybe a hybrid. A half pipe, black in the bottom to absorb sunlight and covered with glass to let light in and trap the heat. If its airtight you can use a compressor to suck the humidity out while lowering the pressure in the structure which makes it easier for more water to evaporate. The vapor sucked out is compressed into a tank until it becomes liquid again. This also raises the temperature quite alot. You use fresh, cold seawater to cool it down in a heat exchanger. Now the freshly produced freshwater should be cool enough to be pipe-lined to where it is needed. The seawater that got heated in the exchanger is pumped into the beginning of the pipe. This way to will have utilized the heat contained in the evaporated water. Watervapor <=> water + heat.
The compressors and the various pumps will consume electricity. Those can be powered by photovoltaics. Conserving as much energy as possible is key to making the thing realistic. Oh, and there are alot of places where ocean meet desert. Northafrica, Arabian peninsula, Australia, Golfo de California (Mexico), Namibia, Chile. Pumping seawater to the desalinization plant may not be the best idea. Where would you put the brine? The saltwater leftover? Some might be turned into salt but it would be better to pump it back into the ocean I think.

Answer 2

Water can evaporate at temperatures less than 100 degrees C. Only some of the molecules need enough energy to escape and become a gas. The temperature of water is actually the average kinetic energy and there are molecules that have more or less than this amount.

Water could just be left to sit and evaporate onto the plastic. However, it would take a very long time to get sufficient amounts of pure water so it is boiled to vaporize faster. Boiling the water takes a lot of energy. In the desert, solar panels could be used to get it and heat up the water faster.