Ocean thermal energy conversion

[25362]

Although the efficiency of an engine operating between, say, 25^oC (surface of tropical oceans) and 5^oC (hundreds of meters down) is just 7% (= 1 - 278 K/298 K) there are sufficiently large amounts of warm ocean water to consider exploiting this free energy of solar origin.

Can anyone enlighten us on the progress and practicality of OTEC ?

 

[epoisses]

Sorry for not responding to your question and going off-thread immediately, but wouldn't such forms of non CO2 producing energy use lead to some form of climate change as well? Changeing temperature patterns in the oceans doesn't sound completely innocent to me.

 

[25362]

Epoisses,

Your comment is appropriate, but can one tell what man-made heat engine doesn't somewhat, directly or indirectly, alter "natural" equilibrium ?

 

[KENAT]

http://www.google.com/search?hl=en&q=Ocean+thermal+energy+conversion&btnG=Google+Search

I only really looked at the first one. Involves heat exchangers etc.

I'm having crazy ideas like using a giant thermocouple or maybe something utilizing the differences in salinity &/or density (I'm guessing density differences would be too small).

 

[moltenmetal]

Here in Ontario they're not bothering to use the deep lake water from Lake Ontario to run a heat engine: they're using it to minimize the need for mechanical refrigeration for air conditioning for the big office towers and municipal buildings in downtown Toronto.

http://www.enwave.com

For a heat engine with a Carnot efficiency of only 7% max, you'd have to do it on an enormous scale to make it worthwhile. Even if the energy source is free, capital isn't.

 

[SnTMan]

moltenmetal pretty well sums it up, there have been proposals of one sort or another of varying formality for about as long as I can remember, but projects are huge scale, very capital intensive, probably payback is so long they never go anwhere. Look how long it takes to permit things we already know how to do.

Regards,

Mike

 

[GregLocock]

Here's a similar concept that's completely different.

http://en.wikipedia.org/wiki/Solar_updraft_tower

Looks at once vaguely feasible, rather expensive, and really quite intersting.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Schipperus]

How about another way of retracting power from the ocean??

http://en.wikipedia.org/wiki/Tidal_power

It's been done already.

IJsbrand

 

[0707]

Tidal power seems a good energy solution and it is already being used.

Suppose the pioneers on this technology were the Dutch

 

[0707]

For OTEC (Ocean Thermal Energy Conversion) go to

http://library.thinkquest.org/26366/text/alternative/otec.html

 

[Schipperus]

Actually, tidal power is no issue in The Netherlands. The height difference of the tides aren't high enough.

 

[LCruiser]

There are innumerable methods of converting solar energy (including ocean thermal, tides, etc.) to useable energy. As my dad, who was an engineer at LANL used to say, it's pretty easy to kick your feet up on a desk and figure out a theoretical way to do something. It's an entirely different thing to cost effectively make it happen. That's what engineers do. Make it happen.

 

[KENAT]

I seem to remember learning in school when I was about 14-15 that almost all the current major energy sources are based on solar energy if you go back far enough.

Geothermal and Nuclear are the 2 exceptions that spring immediately to mind. I guess burning sulfer and similar chemicals would be a problematic third.

 

[HVAC68]

The biggest drawback for OTEC is its huge initial investment.

HVAC68