""At the heart of each island is an ocean thermal energy conversion plant which can create electricity from sea water where the difference between the temperature of the surface water and the deep is 20C or more. The warm sea water is pressurised to transform it into vapour which drives a turbine. The vapour is condensed against a surface cooled by water from the deep, to produce desalinated water. The energy from this technology, which was originally invented in 1881 by a French engineer, would be supplemented by wind turbines and a "power tower" which captures energy from the sun by using mirrors to focus solar rays on a central "furnace".""

http://www.nextenergynews.com/news1/next-energy-news1.10c.html