World's Largest Ocean Thermal Power Plant Planned For China

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."

Comments

Could OTEC help w/ algae biofuel?

[ebno-10db]

Could OTEC help produce algae for biofuel?

AFAIK nutrients are a serious constraint on the large scale use of algae for biofuel. For pilot plants you can always dump in fertilizer, but on a large scale it might be different, due to the energy required to make that fertilizer and the fact that there is a limited supply of phosphates. Even sewage has its problems, as there is a limited supply (though some contribute much more than others) and it may be better used for agricultural fertilizer (humanure). However, deep ocean water often contains lots of nutrients because dead plankton tend to sink. That's why you get lots of phytoplankton (green water) in parts of the ocean where there are upwellings. Could the deep water that's brought to the surface for OTEC be used to fertilize algae grown for biofuel?

OTEC is just a funding vessel for other technology

[sonoronos]

OTEC isn't a serious contender for green energy. It sounds good because it seems to combine romantic elements of green energy: limitless sea water, temperature gradients with huge thermal sinking ability, minimal environmental impact, etc. The truth of the matter is that OTEC has serious fundamental limitations, the worst of which is the fact that economically viable energy output requires enormous amounts of water flow - beyond what is capable with modern technology. Pulling an ultra-high flow water column from deep enough in the ocean to create a good thermal differential from surface water requires enormous pipes, which current materials technology can't deliver - because the tensile strength of even the strongest materials would buckle under the weight of the pipes themselves. Heat exchanges have to be very efficient, and sea life/creatures easily clog up the internals of the heat exchangers, so conformal coatings have to be developed to allow good thermal transfer while preventing the accumulation of bio. Finally, it just can't compete with simple proven solutions like hydro-electric. Look at any company that bids on OTEC and you'll see that the real funding vessels are in conformal coatings, materials technology, and pump technology, among other things. I don't forsee anyone building a viable OTEC plant for the purpose of commercial energy production anytime soon.

Re:And anybody who complains about the unsightly v

[ShanghaiBill]

This system requires deep water. The deeper the better. Think over a mile deep.

Seawater at that depth is rich in nutrients. Ocean thermal plants could be combined with aquaculture to make them more cost effective. After the water is drawn up and warmed in the heat exchanger, it is released at the surface. The nutrients result in a plankton bloom that can be eaten by fish, shrimp, oysters, etc.

I remember when the US used to do this stuff

[GodfatherofSoul]

Back before we became a bunch of short-sighted corporatists who laugh at anything that doesn't turn a profit in one quarter.

Re:I remember when the US used to do this stuff

[dbIII]

The US gave up on that sort of stuff some time between 1970 and 1985. It became easiler to sit back and let the money roll in, or businesses were handed over to idiot sons, or any of a million other things that meant most US innovation happened in Silicon Valley carried out by people that had only recently arrived in the USA.

Re:And anybody who complains about the unsightly v

[ebno-10db]

Because China has such a stellar environmental record.

No, and I can give you a mile long list of serious complaints about the Chinese government, in terms of both their domestic and foreign affairs. But give the devil his due. At least they're trying something here. You know, kind of like the United States once had the guts to do?

Re:OTEC is just a funding vessel for other technol

[Firethorn]

because the tensile strength of even the strongest materials would buckle under the weight of the pipes themselves.

Couldn't this be handled by ballasting the pipes along their length to maintain neutral buoyancy?

But yeah, there's lots and lots of problems to solve with this.

I'm reminded of a show involving an aquatic zoo that mostly works off of piped in seawater - they have an enormous crew that's devoted to simply cleaning and maintaining the involved piping, because of the bio accumulation. One method they use is an iron 'pig' that they send through using high pressure to scrape off the collected masses inside the pipes. The forces involved are so much that the 'pigs' don't last long.