Ocean thermal power is a dream that’s been in the works for seven decades but has yet to take off as a viable energy option. However, the Navy and Lockheed Martin are putting greater efforts into making it a reality, reports EE News (sub req’d).
EE News: The basics are well-accepted. With 23 million square miles of surface area — 70 per cent of the Earth — the ocean is the world’s biggest sunbather. The amount of heat it absorbs each day is equal to burning hundreds of billions of oil barrels. Tapping into even one-tenth of a per cent of that energy, the National Renewable Energy Laboratory says, would yield 20 times as much electricity as the United States uses in a day.
Engineers have two main ways to mine this resource. In the first, hot surface water is pumped from the ocean and used to heat a working fluid that boils at low temperatures. As the vapor expands, it pushes a turbine to generate electricity. Then exposing the vapor to cold deep-ocean water turns it back into fluid, ready to be boiled again.
The second way is called “open-cycle,” and it can make more than electricity. Warm, salty water is piped into a vacuum, where it becomes water vapor and turns a turbine, generating power. When it meets cold ocean water, it becomes fluid again — but since the salt was lost during boiling, the process has a side-product of fresh water.
Unlike solar or wind, ocean power can provide a better, more consistent flow of electricity. Ocean power can only be used in certain areas though: 20 degrees north or south of the equator. As a result, Lockheed Martin is exploring using the technology off the coast of Hawaii.
If properly harnessed, the technology could provide enough electricty for all of Hawaii and Naval vessels could use the powering sytem for their barges.
All this adds up well for Lockheed Martin, which is actively seeking new ways to use wave power. Earlier this year, the company announced plans to team up with Ocean Power Technologies to develop a project off the coast of Oregon or California.