Surfs up, bills down
Before long, the ocean water in Hawaii could be used for more than just surfing. Several hotel owner in Waikiki are looking to use cold deep-sea water to power air conditioning. The cold water from the ocean would be pumped into a heat exchanger that would chill a closed container of fresh water. The fresh water would be used for the air conditioning and the sea water returned to the ocean. Hotels could potentially save 20% on their cooling costs.
http://www.staradvertiser.com/business/businessnews/20100809_The_cooling_wave.html