I want to comment on this link which was in the Feb 04 news brief.
See this link to full article

This is very bad news. Many organisms (especially marine) are very sensitive to the ph of the environment. Dissolved CO2 (through simple chemistry) becomes carbonic acid. Many scientists feel the oceans have been acting as a 'sink' by absorbing a large percentage of the CO2 (billions of tonnes per year) being released. This apparently is having the effect of flipping the ph of the oceans from slighly alkaline to acidic.

I want to consider a worse case scenario - a large scale collapse of the base of the ocean's food chain - plankton. My understanding is these small organisms are responsible for 60-70 % of photosynthetic processes on Earth. What would be the consequences of their death?

Forget the effects on the oceans food chain for the time being (they would no doubt be catastrophic). Our atmosphere would not be 20% oxygen if it weren't for photosynthesis. If all photo-synthesis were to cease on Earth, oxygen levels would decline as those reactive O2 molecules get bound up. My question is how long would it take O2 levels to drop (assuming a major hit to photosynthesis) before they declined to the point where people would have trouble getting enough oxygen from the air just breathing? Can anyone think of anything which might accelerate the loss of O2?

Currently, plants are a sink for CO2 - they use it for photosynthesis, and this is helping to slow the CO2 rise. So, losing a big chunk of the photosynthetic community would accelrate the rise of CO2 (and the loss of O2) - but how much? Seems to be nothing but very bad new lately

Wow...
we are just about to f*ck ourselves with a splintered wooden broom.
George Carlin said it best...

Wow. It's ecologically friendly, it generates enormous power and it's available anywhere with access to deep ocean water. And guess what! The guy behind it isn't even a kook.
link And here I was worried about peak oil for nothing. And another thing, this thing produces so much power that it could actually make the Hydrogen economy work.

[edited by MQ}

I don't think it would make the hydrogen economy work. Hydrogen is too difficult to transport for the uses envisioned and OTEC would not be cheap. What it does do however is provide the potential for tropical island/ developing nation electricity self sufficiency in addition to a potential added source of vital marine protien, fresh water, air conditioning etc. These are all extremely valuable and promising applications.

link This looks like a press release. I want hard numbers That's the only way science really gets done.

Ahh.. another heat pump..

And ecologically friendly? One wont hurt, but build thousands of these around coast and you will ruin marine life there (by changing ocean temperature)

http://www.poemsinc.org/FAQOTEC.html

Very low energy efficiency.



They are still trying to have positive EROEI



Even after reading the article you posted, I asked myself some hard question :
(1) What's the initial amount of conventional fuels to start the pumps working?
(2) What's the energy used to pump, say, 3000 tons of cold sea water?
(3) What's the energy generated by the steam turbines after getting BOTH the (equal amt?) HOT sea water and that 3000 tons of cold sea water?
(4) What's (3) minus (2)?

If (4) is still negative, it is not self-sustainable.

{Post copied from deleted duplicate thread by MQ}

From the article:



Infinite energy, perfect health, and lots of grapes.

Now I ask you, what more could anyone want?

Hmm he managed to Wrangle up 75+ Mil in funding. I wonder if I can get his investors list.

If they'll drink this swill, I've got a Lunar Uranium Mining Project, I'd like to pitch to them

OTEC has been under development for some time. The plant near Kona hasn't achieved sustained net energy production. A great deal of energy is used directly in just pumping the seawater up into the system If you look at the details at OTEC you'll notice the requirements of siting and their maximum net power production achieved.

The breakthrough--financially--for OTEC was the horticultural one. The irrigation system/heat exchange and good crop production was what finally allowed them to break even. Notice the Saipan plan relies on the financial "subsidy" from the ancillary benefits (and the emphasis in the article on pineapple and grape production), and the plan doesn't state they can solely rely on OTEC power to run the complex.

It's thermodynamically interesting and possibly an appropriate local energy source if the remaining technical challenges are worked out.

And there's an excellent nude beach near the Kona OTEC site if you want to go visit one day

From the reports that I have read (3) - (2) is a positive number. It has been proven experimentally several times with net power being produced. It is estimated that about 25% of the produced energy of a recent design would be used to run the plant, pump etc. (Uehara cycle) The great unknown is the net energy after embedded energy in steel, titanium, cold water pipe etc. is considered.

Andy,

Lemme re-read the article once again. But you're right. Sparaxis's link had a few more OTEC links (need pdf) which could be worth reading further for more concrete figures. However, I must say the initial page has a little disheartening portion



Could I digress a little? I guess the major challenge is the perpetual upkeep of the pumps drawing water up. Wasn't there a similar thread somewhere which initially talked about the use of pumps to draw water from deep within ground for warming in the winter, cooling in the summer?

I just hope that whatever alt tech is used in the hopes of replacing fossil fuels succeed, and FAST. OTEC seems quite interesting -- attempting to solve both energy and food at the same. Still I worry most about the stage whereby an OTEC plant is (energy-only) self-sufficient -- can the energy be transformed for maintaining and/or building/jumpstarting more plants? [1] Cutting steel, making the pipes, pushing it 1000km/3000ft underwater, making the parts for replacements. Granted fossils may not disappear overnight....but still....gawd, at present current events it had hell better be fast in solving [1]

I wonder what the EROEI on buring pineapples and grapes is?

Seriously though, when you consider that anhydrous ammonia fertilizer comes from natural gas the EROEI on OTEC + horticultural has to take into account the displaced natural gas (if any.)

Edited to add this:

http://www.fortwayne.com/mld/journalgaz ... 733929.htm

Why burn that? Grow Palms, rapevine, ect... for oil.

I remember in my geography classes in the late 80s that OTEC was one of those promising up and coming energy sources. 15 years later it still appears to be up and coming. Just like fusion
Just like oil shale oil

Now unlike those other two, I do think there are some possibilities for this technology. Like other renewables, implementation will be limited to a few areas and small sizes. Just like Licho said, environmentally benign in small doses. No one apparently seems to be concerned what the effect of artificially modifying ocean temperature would be. It was the same with hydro. Small projects had almost no environmental impacts. Nobody would argue that the construction of the Aswam or Three Gorges dam were benign to the environment, even if the power generated was pollution free.

From what I read about these projects, the best efficiencies are found in tropical seas where the temperature variations are the greatest. Heaven forbid we start plopping OTEC units down willy-nilly and wind up dislodging methane hydrate deposits. Plus OTEC has no use if you are not situated near deep ocean waters.