Ocean Thermal Energy Conversion, anyone?

[Dead_Parrot]

I've noticed in the latest (treeware) version of my local rag that there's a spat between China and Japan over the Okinotorishima Islands, and Japans plans to install an OTEC generator to win it.

Politics aside, I don't recall OTEC being mentioned in E/E: In fact, I'm pretty sure the only reference I've seen was in a sci-fi novel, but a bit of googling throws up a few trial schemes to test if it's useful...

The wiki is here, and has some interesting-looking links at the bottom for us ignoramuses who know nothing about it. Any thoughts or comments?

[LiberalEsto]

1. Sounds a lot like the way heat pumps work

except that heat pumps use air, not water. And ground source heat pumps use the temperature of the ground to generate heat.

[Dead_Parrot]

3. I think they're the other way around

Heatpumps move heat using electricity, whereas these generate electricty by moving heat. My brain is starting to implode under the thermodynamics of it all... :(

[TheBaldyMan]

2. is this the alternative energy source that uses the temp.

differential between the surface and deep oceant to drive a turbine? In that case its the same as geothermal but with a smaller end point difference in temperature. The idea was floated way back in the seventies but the high capital cost at the time meant there was no large scale prototype constructed to find out if this could extract an economic quantity of power.

IIRC the turbine used ammonia as the volatile gas/liquid used to propel the turbine.

[jwirr]

4. When I first started reading the magazine Ode there

was a small article about a tiny orb that could be placed in the current and it would produce energy even from small movements. This sounded interesting to me because I was living on the north shore of Lake Superior. I lost the article and have never been able to find it back. I think this would certainly be a good solution for communities near lake and rivers.

[skids]

5. That's more ocean kinetic.

There's a good diary at Kos about tidal systems: http://www.dailykos.com/storyonly/2005/11/11/71747/496

There are some links in the comments about wave kinetics as well.

OTEC though is an entirely diferent animal -- it moves hot and cold water around and grabs the energy by heating up the cold ocean water from below. I'm not sure how I feel about it. Heat (or removal of cold water) can constitute pollution for a deep ocean biosphere. The kinetics look more friendly at first blush than the OTEC systems.

[jwirr]

7. I agree with you about the dangers. Vine Delorean, a

Native American from the 70s, said that "God created the world perfect andman has tried ever since to change it." I think that anything that changes the natural balance of nature is playing with danger. The motion orb would at least use what is in the form it comes in. Thank you for the links.

[Dead_Parrot]

8. I'm a bit leery of tidal...

The best places to put tidal barrages tend to have lots of nice tidal wetlands behind them, which get screwed over when you start bottling the water for power.

I guess how much OTEC would screw up the oceans thermal gradient would depend on what currents run near by...

[phantom power]

6. I think there was a thread on this a while ago...

But anyway, here's a link to OTEC in Hawaii:
http://www.hawaii.gov/dbedt/ert/otec_hi.html