An Ocean Thermal Energy Conversion (OTEC) pilot plant off the coast of Hawaii’s Big Island is now a step closer to reality. The U.S. Naval Facilities Engineering Command (NFEC) has just awarded Lockheed Martin a US$4.4 million contract modification to develop critical system components and designs for the plant – this amount is in addition to the $8.1 million contract the NFEC issued in 2009, as well as two grants totaling $1 million that Lockheed Martin received from the U.S. Department of Energy in 2008 and this March. Hopefully, this means the streets of Kona may someday be lit by electricity obtained from the temperature difference between warm and cold sea water.

OTEC centers around a closed system, which the sea water heats and cools. Here’s how it works...

Warm, sun-heated water from the top layer of the ocean passes through a heat exchanger, which causes a “carrier liquid” with a low boiling point (such as ammonia) to turn to steam. This steam travels up a pipe to a turbine, where it generates electricity. The steam then condenses back to liquid and travels down to another heat exchanger, this one cooling the liquid with cold seawater from lower depths. From there, a pump brings it back up to the first heat exchanger, and the system continues on ad infinitum.

The system is reportedly completely non-polluting, and is capable of providing power to warm-climate seaside communities 24 hours a day.

Lockheed Martin’s involvement with the field of OTEC dates back to the 70s, when it built a prototype plant that ran for three months.

The Hawaii pilot plant is expected to have a 10 megawatt capacity, and be operational by 2012 or 2013. It is hoped that its success will lead to commercial-sized plants generating 100 MW or better, by 2015. According to Lockheed Martin, such a plant could meet the electrical needs of a small city.

All images courtesy Lockheed Martin