After 30 years, there has been a renewed interest by investors, the military in particular, in exploring the development of ocean thermal energy conversion. Hawaii is one of the hot spots. 

Even Forbes is taking notice:

Scientists have entertained the idea of OTEC since the 19th Century and Lockheed Martin created a working model during the 1970s energy crisis . But the budding market withered in the 1980s as fuel prices dropped. Now, with energy prices rising again, OTEC is back.