The Seawater Greenhouse offers a low cost, sustainable solution to the problem of providing water for agriculture in arid, coastal regions. "The process uses seawater to cool and humidify the air that ventilates the greenhouse and sunlight to distill fresh water from seawater. This enables the year round cultivation of high value crops that would otherwise be difficult or impossible to grow in hot, arid regions The overall process is extremely energy efficient. 1kW of electricity expended on pumping will remove 500kW of heat. Water can be produced at low energy costs (<3kWh/m3)". Much better than building a nuclear power plant to run a traditional desal unit. See earlier TreeHugger post on an analogous, but far less promising looking project here .
Via: The Guardian .