Desalination without a membrane

People have wanted to turn sea water into drinking water for years. Unfortunately, it's not cheap.

The reverse osmosis process, which separates out salt with a membrane, costs about 50 cents per cubic meter of water. Reverse osmosis systems also have to be monitored so that the membrane doesn't get fouled or clogged. Last year, Ashkelon in Israel opened a $250 million plant that will ultimately churn out 100 million cubic meters of water annually.

Quos, a stealth company out of Chicago, has come up with a technique for removing the salt and other impurities without membranes, according to Vinod Khosla, whose firm, Khosla Ventures, has put money into Quos. The company, like some of the other companies Khosla Ventures has put money into, can in some ways still be looked at as a science experiment, he acknowledged. He wouldn't say much more about Quos, but with all of the money going into water, stay tuned. (We spoke to him briefly after a presentation at the ThinkGreen conference taking place in San Francisco.)

Khosla Ventures also put money into NanoH20, which grew out of a research project at UCLA. NanoH20 has developed a membrane that attracts water molecules and repels other types of molecules, thus speeding up the desalination process.

Quos isn't the only desalination company out there without membranes. Altela in New Mexico has come up with a shipping container-size device that simulates the evaporation-condensation cycle that you see in nature. The company, in other words, makes rain and removes impurities that way.

Other notes from Khosla:

--One of the reasons that grasses like Miscanthus make better sources for fuel feedstocks than plants like corn is the fact that they are perennials. Every year, the roots grow longer and deeper. "You only need a little water and fertilizer. That is why perennials are the key," he said.

--The biggest obstacle facing the solar thermal industry is transmission lines. Solar thermal plants need to be built in the desert, but the power has to be distributed to distant population centers. The Department of Energy is experimenting with ways to beef up the transmission grid. Solar thermal, which makes electricity by harvesting heat from the sun, can produce electricity for close to the same price as natural gas plants and will approach coal plants in the next few years, according to advocates.

--And of course the usual Vinod comments: biodiesel is not so hot, ethanol is going to be cheap, and photovoltaics can't do much to solve global warming.