Environment

World’s largest OTEC power plant planned for China

World’s largest OTEC power pla...
Lockheed Martin and Reignwood Group plan to develop a 10 MW prototype OTEC pilot plant off the coast of southern China
Lockheed Martin and Reignwood Group plan to develop a 10 MW prototype OTEC pilot plant off the coast of southern China
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Tropical regions are considered the only viable locations for OTEC plants due to the greater temperature differential between the shallow and deep water
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Tropical regions are considered the only viable locations for OTEC plants due to the greater temperature differential between the shallow and deep water
A closed-cycle OTEC system
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A closed-cycle OTEC system
OTEC plants are located off-shore
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OTEC plants are located off-shore
Lockheed Martin and Reignwood Group plan to develop a 10 MW prototype OTEC pilot plant off the coast of southern China
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Lockheed Martin and Reignwood Group plan to develop a 10 MW prototype OTEC pilot plant off the coast of southern China
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Lockheed Martin has been getting its feet wet in the renewable energy game for some time. In the 1970s it helped build the world’s first successful floating Ocean Thermal Energy Conversion (OTEC) system that generated net power, and in 2009 it was awarded a contract to develop an OTEC pilot plant in Hawaii. That project has apparently been canceled but the company has now shifted its OTEC sights westward by teaming up with Hong Kong-based Reignwood Group to co-develop a pilot plant that will be built off the coast of southern China.

OTEC uses the natural difference in temperatures between the cool deep water and warm surface water to produce electricity. There are different cycle types of OTEC systems, but the prototype plant is likely to be a closed-cycle system. This sees warm surface seawater pumped through a heat exchanger to vaporize a fluid with a low boiling point, such as ammonia. This expanding vapor is used to drive a turbine to generate electricity with cold seawater then used to condense the vapor so it can be recycled through the system.

A closed-cycle OTEC system
A closed-cycle OTEC system

Tropical regions are considered the only viable locations for OTEC plants due to the greater temperature differential between the shallow and deep water. Unlike wind and solar power, OTEC can produce electricity around the clock, 365 days a year to supply base load power. OTEC plants also produce cold water as a by-product that can be used for air conditioning and refrigeration at locations near the plant.

Despite such advantages, and even though demonstration plants were constructed as far back as the 1880s, there are still no large-scale commercial OTEC plants in operation. This is largely due to the costs associated with locating and maintaining the facility off shore and drawing the cold water from the ocean depths. But the time may finally be right.

With the shelving of the Hawaii OTEC pilot plant, the 10 MW prototype offshore plant will be the largest planned OTEC project to date. Like the Hawaii project, which was also to be a 10 MW facility, the China OTEC plant is designed to pave the way for higher capacity plants ranging from 10 to 100 MW.

OTEC plants are located off-shore
OTEC plants are located off-shore

The plant is to be built off the coast of southern China to supply 100 percent of the power needed for a large-scale green resort community being developed by Reignwood Group. The new resort is planned as Reignwood’s first net-zero community, with the company also currently developing two large-scale low-carbon resorts and others planned for key locations in China.

Lockheed Martin and Reignwood will begin concept design of the sea-based prototype plant this year with construction due to begin next year. Once it is up and running, the two companies plan to use the knowledge and experience gained over the course of the project to improve the design of additional commercial-scale plants.

The companies claim each 100 MW OTEC facility could produce the same amount of energy in a year as 1.3 million barrels of oil and decrease carbon emissions by half a million tons. Assuming oil trading at near US$100 a barrel, they estimate fuel savings from one plant could exceed $130 million a year.

The video below from Lockheed Martin describes the OTEC process.

Update: We heard back from Makai Ocean Engineering, which was involved in the 10 MW pilot plant project planned for Hawaii. While the company believes a 100 MW plant would still be viable for Hawaii and would provide power at a lower rate than is currently available from existing sources, a 5 to 10 MW pilot plant would be a necessary stepping stone to validate the main OTEC systems and give a better idea of the cost projections for a larger-scale commercial plant. Unfortunately, current cost estimates suggested that a 5 to 10 MW plant wouldn't be cost effective at the time so the U.S. Navy was unwilling to invest the money required to finance the project.

Sources: Lockheed Martin, Reignwood Group, Makai Ocean Engineering

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30 comments
Nairda
Good to see LM slowly making an effort to atone for decades of building war machines. We are slowly moving from the age of technology to the age of Integrity, Wars will no longer be viable due to our close economic and social inter-dependency. Smart players will see this and diversify core business.
Slowburn
I can't believe that boiling a fluid with a low point to drive a turbine and the re condensing it is more efficient than using a Stirling Cycle engine. Air temperature is often a little higher than the water temperature and the simplest, cheapest passive solar thermal collectors will add a significant amount of energy to the system. I don't thing that building and maintaining a deep water structure is really cheaper than building the additional miles of insulated pipe to bring the cold water to shore, even with the difficulty of winding it in through a breakwater. especially if you can add industrial waste heat to the equation.
Siegfried Gust
Slowburn, my thoughts exactly. Coupling this to a high heat output industrial operation and pumping in the cold water would seem to make far more sense. The temperature differential would be far higher, allowing for far more power output.
Alastair Carnegie
A Calorie is 4.184 Joules. A Watt is one Joule per Second, and a Calorie is the amount of heat needed to raise one cc. of water one degree centigrade. A cubic Hectare, 100 meters cubed. is a million tonnes. and a tonne is a million grams. or ccs of pure water. This gives the 'available' energy from a cubic hectare as, 4,184,000,000,000 Joules. per degree centigrade temperature change. This translates to 1.162 Gigawatt hours per cubic hectare per degree centigrade....of 'available energy'. Reality dictates that with low temperature difference the coefficient of performance is also very low. But this is less important with free energy! Volume is what counts! Penn State University have done substantial research on Thermo-Acoustic effects, eg. Benn & Jerry Thermo-Acoustic Refrigeration, as well as the reverse effect. Ear-piercing noise! from a thermal source. Just a thought, OTEC Thermo-Acoustic Power hypothetically could be very simple to construct. Just a long tube and bucket-brigade honey-comb heat exchange baffle. Hmmm?
Arahant
I have to believe that Lockheed martin has looked at alternatives and is going with the choice that makes the most sense, they have a team, many teams of people who have spent their entire lives to that point studying and practicing the field of science specific to this sort of thing, and they are the best out there because lockheed makes so much money. I have to believe they know more then people on the internet, who may be smart and have common sense ideas but the idea that a better solution would be simple and off the top of your head is just egotistical i think. No offense to anyone, i'm no expert either and i probably know less then others who have commented before me about this specifically, but i prefer to give people the benefit of a doubt when they're in a position worthy of that.
Steve Jones
I'm not sure but I suspect the heat source (warm seawater) and heat sink (cold seawater) are a significant distance apart and that's why it's not possible to build a physical heat engine linking the two.
Tommy Maq
They tried an offshore 'pipe' system in LA years ago and found that it was cheaper to pipe the cold water directly into the heat exchangers in the buildings that wanted the AC (which is a major source of demand for electricity there.) The temperature differences make long pipes very inefficient for energy conversion; most OTECs operate on temp differentials of just 40 degrees, and the friction in the main cold pipe uses about 30% of the available energy; extending that pipe by a factor of two would essentially destroy the advantage. I do find it strange that everyone keeps designing sea-bed anchored plants, instead of floating, which could then go wherever the thermocline is best. @ Araphant; The Wright brothers invented the motorized airplane at a time when all the major industrial players were seeking exactly that kind of thing, and failing. Unlike the 'smart guys' who thought they knew all the answers, or that the science was settled, or that money would make it happen, Orville and Wilbur went back to first principles, did straight science (with their own home-made wind tunnel) on a shoestring, and succeeded. Don't write off the amateurs so glibly; they frequently have the freedom to explore that the 'big money' doesn't, and that can make all the difference, as the Wrights proved so dramatically. (And if you are worried about credentials; I've got a degree in astrophysics and have been studying OTEC since I first read Marshall Savage's great book "The Millennial Project" in 1998. If I had an extra $400,000, I'd float my own design approximately tomorrow.)
f8lee
Hmm - in 100 years when these types of devices dot the oceans will there be concerns about reducing the temperature gradient in the ocean leading to changes in the gulf stream and other similar sub-surface flows? Of course, by then the glacier melts could reduce the ocean's salinity by ehough to make those changes anyway, so maybe it's moot.
billybob1851
if this thing really does save 100 million barrels of oil per year, i like it...
Don Duncan
Tommy: If only the Wrights had listened to the Frenchman that gave them a model of his self-stableizing craft. Instead, they assumed the stability should be supplied by the pilot. Subsequently, they warehoused the superior design that solved their most pressing problem. Three years later, a storm blew down the shed and destroyed it. Their narrow focus delayed success and resulted in the fixed wing being accepted over the rocking wing (control wing) design. The result was a century of unnecessary deaths do to stalls. I would like to know why the OTEC plant was moved. Was it the unfriendly business atmosphere in Hawaii?