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World’s largest OTEC power plant planned for China


April 18, 2013

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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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.

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.

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

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

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.


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.


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.

Siegfried Gust

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?

Alastair Carnegie

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.


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.

Steve Jones

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.)

Tommy Maq

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.


if this thing really does save 100 million barrels of oil per year, i like it...


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?

Don Duncan

I get a bad feeling about this technology. Mother Nature keeps the temperature differential to maintain the Earth's temperatures. People are screaming about global warming pf the air, but now they want to warm the colder portions of the ocean? Also, what happens to the area downcurrent of the cold water exhaust? It sounds ocean-life-changing. You know, this concept seems about as good as sinking leaky pipes through our limited supplies of fresh water and pumping deadly toxins down there to frack the natural gas. These toxins can and will leak into our water supplies. Who ARE these people?


re; Tommy Maq

Get a larger diameter pipe.

re; Nairda

Building the tools to defend against aggression does not need to be atoned for as it is a good thing. Close economic and social inter-dependency does not restrain the evil from trying to steal that which is not theirs.

re; Don Duncan

The stability that the Wrights didn't use didn't affect stall and the wings that do resist stalls make emergency climbs less effective.


re; f8lee

Currents are wind and cold water sinking driven. Warming the deep water is more likely to speed up the currents by reducing the energy required to lift the water from the oceans depths.


odd why Hawaii would cancel that project, very Eco, right.

Stephen Russell

re; ljaques

The life in the cold water currents will probably benefit from the ever so slight increase in temp. assuming that the cold water is not discharged above it.


There are a great many ways to make electricity the thing that strikes me and concerns me a little is the author of this piece did not bother to find out why the project was cancelled in Hawaii . I will bet that the reason had something to do with the devastating consequence of screwing withe the temperature of the sea water to fish and marine mammals. From the comments posted you would hardly be blamed for thinking that global warming and rising sea levels were not the greatest threat to human life continuing on this planet. Personally I think the days of specialist thinkers is DEAD you are all smart enough to know more then one subject. There is nothing particularly new about thermal exchanges you can do it with all kinds of fluids and you don't have to mess with the ocean to do it. The ocean is not a toilet it is not something we can afford to abuse any more. One other thing being a dinosaur doesn't make Lockheed right about anything it just makes them hungry for their next trick.This a pretty stale saturday night effort.


"apparently cancelled". Is this another casualty of the sequester? I can't find any other article that corroborates this project's (the one in Hawaii) cancellation.

Leo Baldwin

So picture this. As far as the eye can see, all around the OTEC plant are wave energy harvesters. These would be used to supplement the net power and/or the desalinated water production of the OTEC plant. More importantly they would dissipate wave energy to minimize floating platform motion and damage.

Leo Baldwin

This is a waste of resources compared to what you could get with wave energy.


I would say that as soon as the environmentalists got really going in Hawaii the costs projected took them out of any chance at profitability. Just a guess, being the case that their costs were allowing the project to actually be matched to Hawaii in the first place. Now factor in the fact that America is looking at any way possible to expand our interaction with China on most fronts, it probably got a few nudges in that direction from the feds. Also, there is the fact of their long-term Senator having died recently. I'd say that the truth of why move to China is found somewhere in there.


It occurs to me that a deep water geothermal plant could work well.

The only source I could find said the Hawaii project was cancelled because the navy declared it nonviable. http://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion


re; b@man

Wave energy is not available all the time, OTEC is.


http://en.wikipedia.org/wiki/Enwave Not quite OTEC but an actual commercial use of deep cold water!


Gentlemen,this process described is a stirling cycle.The expander is a turbine instead of a piston engine.Same hot side and cold side process.

Jochen Demnitz

re; Jochen Demnitz

Rankine cycle and Stirling cycle both extract work by moving heat from point A to point B. In this case Stirling cycle should be significantly more efficient but the Rankine cycle turbines use off the shelf components.


Here is a question: Why don't they use pipes that are "free" of water and create convection with a gas that is sensitive in its volume for that temperature gradient (if one exists). I would think this would save a lot of the pumping inefficiency since as far as I know it takes a lot less energy to pump a gas than a liquid and natural convection would be enhanced? If this sounds stupid I apologize, I barely squeaked by thermodynamics and make a better computer engineer than a mechanical engineer.

Steven Anderson

re; Steven Anderson

Find a gas that expands when cooled and then we'll talk about pressure at depth.


Cut the bull and lets just get modular nuclear power sorted. The USA and the UK are already most of the way there with the technology used on their submarines and warships/aircraft carriers. And the new reactor design which use different fissile materials are almost stupid proof and the possibility of making weapons is with the spent fuel from these is nix.

I do like "power from the sunlight" renewable's such as ocean (wave or thermal differences) wind or straight out thermal and photovoltaic but we need power now whilst also really putting a dent in our carbon emissions. We need change NOW, not in 100 years which is how long it would take sunlight renewable's to make a difference...

Just saying...


ljaques, watch the documentary "Frack Nation"

OTEC has been the next big thing for a long time. The problem with it has been it has to be BIG to be practical. A 10 megawatt OTEC, from what I've read, is about the smallest that generates enough electricity to make it worth building.

Gregg Eshelman

I wished that Lockheed would share the information to the public about their research on the deep water pipe idea's. The tax payer's paid for it!

Mist Lift OTEC does NOT need any NEW technology to be developed. All that is needed is the knowledge to be shared about the deep water pipe and the ideas of how and what to make it of. Mist Lift OTEC is the only concept out there that is the most efficient, considering, that OTEC can be only 7% and the closed systems are only 2 to 3% efficient. But the fuel is FREE!!

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