World's Largest Ocean Thermal Power Plant Planned For China 112
cylonlover writes "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 10 MW pilot plant that will be built off the coast of southern China."
RTFA, only in the tropics (Score:4, Informative)
not like we can build this off the coast of Nantucket
Re:And anybody who complains about the unsightly v (Score:4, Informative)
It will likely be quite a distance off shore. And unlike a windmill, it doesn't have to be 300' high.
Re:RTFA, only in the tropics (Score:5, Informative)
In Stockholm, Sweden we have since many years been running the worlds largest heat pump facility, 225 MW. http://sv.wikipedia.org/wiki/Hammarbyverket [wikipedia.org].
It's using waste water from a nearby waste water treatment facility that serves a large fraction of the Stockholm metropolitan area of some 2M people.
Re:Do the waves matter? (Score:5, Informative)
Maybe I missed it but the picture gives me a vague impression that waves have something to do with it but I didn't see them mentioned? I suppose the water movement wouldn't be much use though.
No, it has nothing to do with waves. It uses the ocean's thermal gradient as a power source: because there is warm water on top, and cold on the bottom, we can use the difference to generate power (much like heat from a conventional power plant). Keep in mind it won't be very efficient, since the temperature difference is relatively low, but since you have quite a lot of seawater to utilize, efficiency isn't terribly important.
Re:Do the waves matter? (Score:5, Informative)
Water has a specific heat of 4.2 kJ/kg*C. If there's a 1 degree temperature differential, that's 4.2 MJ per ton. You have to go a bit deep to get to colder water, but by about 1km down it's around 4 C. So relative to tropical surface water, you're talking about a 25 degree difference, or an energy potential of 100 MJ per ton. Nearly 5 orders of magnitude more per ton than the kinetic energy in tidal currents.
The catch being that it's much more difficult to extract power from temperature differentials than it is from kinetic energy. If it were easy, every car engine would have a stirling engine alongside it to extract energy from the waste heat. But stirling engines generate so little power per mass of the engine that it's more efficient just to forgo the additional weight and dump the waste heat via a radiator.
Re:Do the waves matter? (Score:5, Informative)
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If there's a 1 degree temperature differential, that's 4.2 MJ per ton.
The catch being that it's much more difficult to extract power from temperature differentials than it is from kinetic energy. If it were easy, every car engine would have a stirling engine alongside it to extract energy from the waste heat. But stirling engines generate so little power per mass of the engine that it's more efficient just to forgo the additional weight and dump the waste heat via a radiator.
It's not just "more difficult", it's scientifically impossible to capture all of the power from temperature differentials. The maximum possible efficiency of such a heat engine is described by Carnot's Theorem [wikipedia.org] and is (1-Tc/Th) where Tc and Th are the absolute temperatures of the cold and hot reservoir. So if 100MJ of heat flows from a hot water reservoir into a cold water reservoir through a heat engine you can only capture a single digit percentage of that energy for the temperature differences under discussion
So taking a 25 degree heat difference as 275K cold water and 300K hot water then the optimum efficiency of the heat enginer is only 8.3%, and the actual efficiency will of course be less.