Oceans cover more than 70 percent of the Earth’s surface, which potentially makes them the world’s largest solar-energy collector and energy-storage system. According to the National Renewable Energy Lab, if less than one-tenth of 1 percent of this energy could be converted into electricity, it could supply more than 20 times the total electricity used in the United States in a single day.

That is why the U.S. Department of Energy recently selected Lockheed Martin to receive two grants totaling $1 million to advance ocean thermal-energy conversion (OTEC) technology. The grants support an effort to produce an economically viable, utility-scale renewable-energy source using the temperature difference of warm surface water and deeper colder water.

This is not a new concept. In 1930, Georges Claude built an experimental OTEC system in Cuba that produced 22 kilowatts using a low-pressure turbine. In 1993, an experimental plant in Hawaii produced 50,000 watts, breaking the record of 40,000 watts set by a Japanese system in 1982.

Bringing the technology up to utility-scale is the challenge. Under the first grant, Lockheed Martin will develop a tool to estimate the amount of energy that can be extracted from the ocean’s thermal layers. The geographic information will be used to identify regions of the world most suitable for OTEC as well as seawater-based air conditioning (SWAC). SWAC uses cold seawater near coastlines to supply air conditioner coolant and can significantly reduce electric loads during high summer demand periods. It is a proven technology currently in small-scale use in Hawaii; Bora Bora; Stockholm, Sweden; and Ottawa.
This mapping will provide critical information to policy-makers, the energy industry and the public about regional OTEC and SWAC feasibility.