April 22, 2013 10:34 am
If all goes to plan, a new deal inked by two of the world’s biggest companies could give rise to a sustainability advocate’s paradise: a resort near the South China Sea that gets all of its power from the heat of the water nearby through a new type of renewable energy.
The deal, says a news release issued by Lockheed Martin, will see the defense giant partner with the Reignwood Group—a massive company that does everything from selling Red Bull in China to operate hotels and golf courses, managing properties and operating a private aircraft service—to develop the first commercial plant for a new type of renewable energy generation system known as ocean thermal energy conversion (OTEC).
Ocean thermal energy conversion draws on the natural temperature gradient that forms in tropical oceans worldwide. The surface of the ocean, heated by the Sun, is much warmer than the water deeper down. OTEC plants use the warm surface water to boil a liquid with a really low boiling point in a low-pressure container to form steam. This steam then drives a turbine, generating electricity. Colder water from deeper down is pulled up in a pipe, and by having this cold water pass by the pipe containing the steam, the steam is condensed back into a liquid. The liquid flows around, is heated by the warm surface water, and turns into steam once more—on and on, generating electricity from the temperature gradient in the ocean.
The idea for ocean thermal energy conversaion has been around for a really, really long time. “The concept of deriving energy from ocean thermal gradients was a French idea, suggested in 1881 by Jacques d’Arsonval, and French engineers have been active in developing the requisite technology,” says Marine Energy Times.
While Lockheed has been working on this for four decades, one of the first in-depth discussions of the concept came from Nikola Tesla, who at the age of 75 outlined how such a plant might be built in the December 1931 issue of Everyday Science and Mechanics journal. Tesla spent considerable time devising a way to improve the efficiencies of such a power plant, but he determined that it was too great an engineering challenge at the time. “I have studied this plan of power production from all angles and have devised apparatus for bringing down all losses to what I might call the irreducible minimum and still I find the performance too small to enable successful competition with the present methods,” he wrote, though still expressing hope that new methods would eventually make it possible to economically tap the thermal energy in oceans.
So the idea is old, but recent technological developments have driven ocean thermal energy conversion into the realm of possibility. Interestingly, some of the most troubling issues facing OTEC were solved by the oil industry, says the Marine Energy Times:
Ocean thermal is the only remaining vast, untapped source of renewable energy, and is now ripe for commercialization. The near market-readiness of this technology is largely attributable to the remarkable ocean-engineering innovations and successful experience of the offshore oil industry during the past thirty years in developing, investing in, and introducing mammoth floating platforms. That achievement has inadvertently satisfied ocean thermal’s key operational requirement, for a large, stable, reliable ocean platform capable of operating in storms, hurricanes and typhoons.
Consequently, adaptations of those offshore-ocean-platform designs can be spun-off to supply the proven ocean-engineering framework on which to mount the specialized ocean thermal plant and plantship heat exchangers, turbomachinery, cold water pipe (CWP) system, and other components and subsystems.Those offshore engineering achievements have greatly reduced the real and perceived risks of investing in ocean thermal plants.
Lockheed Martin has been working on the technology behind OTEC, too, and the deal with the Reignwood Group will see them build a test plant. If they manage to pull it off, the work could open the door to increased investment in this new form of renewable energy.
According to Green Tech Media, there are some potential environmental issues to look out for: if the cold water brought up from depth is pumped out into the surface waters, you could trigger a huge algae bloom that is really bad for the local ecosystem. But, if you release the cold water further down, around 70 meters depth, you should be able to avoid this dilemma. Having a small-scale test plant will give researchers a way to learn about any other unforeseen issues before moves are made to implement this new type of renewable energy on a larger scale.
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