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On OTEC Can Be a Big Global Climate Influence

The beer sounds great Cliff. The discussion is thought provoking and necessary.

I see what you are getting at but wonder if the interception of wind and wave etc is as effective at dissipating ocean heat as direct conversion to work.

e.g. Much of the surface heat of the ocean is dissipated through evaporation. Atmospheric water is a strong greenhouse gas as SAKURAI points out in the patent application referred to above. Trenberth has also calculated that for every 1C rise in ocean themperature the atmosphere gains an additional 7 percent water vapour and this makes for more intense storms.

OTEC would cool the surface thus reducing both effects. Wind and waves would have some effect but not to the same extent. e.g. Wind is intermittent.  The global gross wave resource is about 3.7 TW as opposed to 14-30 TW for OTEC plus the heat relocation factor. 


September 6, 2013    View Comment    

On OTEC Can Be a Big Global Climate Influence

Robert, with the heat pipe design, cold water is not discharged at the surface. The boiled working fluid descends into the deep where the latent heat of condensation is dissipated into the cold water heat sink at 1000 meters.

As to clouds you might want to read the patent application of Toshihiko SAKURAI;  SEA  SURFACE COOLING SYSTEM UTILIZING OTEC.  

He is so concerned with the potential for thermal runaway due to the warming of the sea surface, he proposes using OTEC for no other purpose than pumping cold deep water up to cool it off.

The patent states, "As the sea surface temperature rises due to the progression of global warming, which has been caused or primarily led by a greenhouse effect by an increase in CO.sub.2, the temperature of air above the sea surface also rises, causing an increase in the density of water vapor in the air above the sea surface. Accordingly, the greenhouse effect is intensified by the increased density of water vapor, causing a further rise in the temperature of the sea surface and the air above. As a result, the density of water vapor in the air above the sea increases more, further intensifying the greenhouse effect. This is so called positive feedback process of the greenhouse effect generated by water vapor."

September 6, 2013    View Comment    

On OTEC Can Be a Big Global Climate Influence

NASA study says we are adding as much as 330 terrawatts of heat to the oceans every year.

If you produced 16 TW of OTEC power, which would require the movement of 320 TWh to the  cold reservoir you would convert or move all of this to the region of low thermal expansion.

Not that I advocate this because it would affect the Thermohaline and degrade the oceans potential to produce power. That is why I believe in the counter-current heat transfer system, which enables the maximum production and thus conversion of heat to work.

I fail to see how wind, hydro, wave or the others have a cooling effect on the ocean let alone a sea level benefit.

September 5, 2013    View Comment    

On OTEC Can Be a Big Global Climate Influence

Work is dumped into the atmosphere in the form of heat with the production and use of any energy.

With OTEC you derive a climate benefit from the production the extent of which remains to be seen.

In view of the research cited it could be significant.

September 5, 2013    View Comment    

On OTEC Can Be a Big Global Climate Influence

If you use a heat pipe design that is exactly what you are doing. The warm surface heat is taken up by the latent heat of evaporization of the working fluid and is dispatched to the deep as the vapor is condensed.

With conventional OTEC it is more a case of the cold water being warmed near the surface.

September 5, 2013    View Comment    

On OTEC Can Be a Big Global Climate Influence

Cliff, I have looked at this reference before. What I see when the salinity is constant at 35 ‰ is:

Pressure 0 decibars temperature 25C coefficient 297 e x 10 6

Pressure 2000 decibars temperature 5C coefficient 157 e x 10 6

Which is precisely my point.

I also do not try to diminish the impact of thermal expansion, which is why I think moving heat to where the coefficient is half that of the surface has a big impact on sea level rise.

I do think though it is fair to say the big mulit meter rise will come from melting ice.

The third cause of SLR is aquifer pumping which Pohkrel et al claim produced about 40 percent of what we have seen to date. Moving water from regions of excess - ie in Canada - to where it is being pumped out, the US Southwest, would therefor be a benefit, which would be doubled if some of the excess was reinjected into depleted aquifers.

There are downsides to massive OTEC and I have worked on minimizing these but this is true of all energy production and in the case of OTEC I believe there are unique and overriding benefits.


September 5, 2013    View Comment    

On OTEC Can Be a Big Global Climate Influence

Cliff, the Levitus et al study says, "We have estimated an increase of 241022 J representing a volume mean warming of 0.09 C of the 0 –  2000 m layer of the World Ocean. If this heat were instantly transferred to the lower 10 km of the global atmosphere it would result in a volume mean warming of this atmospheric layer by approximately 36 C (65 F). This transfer of course will not happen; earth’s climate system simply does not work like this. But this computation does provide a perspective on the amount of heating that the earth system has undergone since 1955.

The point is, I think, the oceans can and have absorbed a tremendous amount of heat in the last 58 years with a very small increase in temperature and therefore thermal expansion.

Trenberth, in conjunction with Kosaka & Xie note, the movement of this heat to deeper waters has brought about what has been called a global warming hiatus over the past 15 years.

The main image for this post is a representation of a classic Carnot heat engine which converts heat to work as it moves from a hot reservoir to a cold one through the engine. (the first law of thermodynamics)

This is also a schematic for OTEC which too converts surface heat to work.

AGW is mainly caused by radiative forcing due to greenhouse gas emissions. OTEC is zero emission energy and therefore would allow for the natural lowering of CO2 concentrations in the atmosphere. As they decline so too will the accumulation of heat in the oceans and that which has accumulated can be converted to work by the process.

Sea level rise is the main problem. Converting heat to work lowers thermal expansion.

The following diagram was posted by Péter Berényi in response to a SkepticalScience post, Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data – comment 53.


It clearly shows the thermal coefficient of expansion of ocean water at 1000 (dbar) – 1000 meters, which is the depth of the cold water heat sink for an OTEC plant – is half what it is at the surface.

Contrary to your assertion, “The redistribution of the local temperatures using OTEC will not ameliorate sea-level rise,” I submit moving surface heat to a depth of 1000 meters would do precisely that. Furthermore the main driver for sea level rise in the future will be polar melting. Tropical storms are the principal mover of heat towards the poles. OTEC would sap the source of energy of these storms thus lessening their severity and would slow down the migration of heat towards the poles.

Berényi said in his comment, “It is not easy to find a realistic heat redistribution pattern that does not increase sea level while sucking in more heat from above.”

OTEC operates 24/7 whereas the oceans are warmed only during the day and first stopping and then diminishing greenhouse gas concentrations would lessen surface warming.

As to where atmospheric heat is being absorbed, I think the first graphic in this article makes pretty clear where this is happening, mostly near the equator.  Further the Levitus study would seem to infer that if the oceans had not absorbed so much heat since 1955 the atmosphere would be considerably warmer.

The shifting of heat to greater depths with a commensurate lowering of the rate of increase of atmospheric warming, seems to me, to be the whole point of the Kosaka & Xie study?

September 5, 2013    View Comment    

On Thoughts on Carbon Capture and Storage Coming from the European Parliament

David, perhaps converting ocean surface heat to work and sequestering even more in the deep is a better answer. Over the last 15 years the latter has reduced the measured rate of atmospheric warming by over 40 percent. The former could produce twice the current primary energy output even as it put global warming on permanent hiatus.

It is disappointing Shell has no interest in such a solution.

September 4, 2013    View Comment    

On Energy Innovation: US Could Tap Into 1400 Terawatt Hours Of Clean Ocean Power

The military has long been a driver of technological innovation.

Calls have been made for all services to evolve to sustainable energy due to the high cost and hazard of getting fuel to the battlefield.

The best option for the Navy is to derive its fuel from its own environment with water as the only by-product of that fuel’s consumption.

OTEC can provide electricity, hydrogen, ammonia or methanol for this purpose.

Hydrogen was used in one of Germany’s first aircraft turbine engines in the 30s, the Russians proposed a liquid hydrogen version of the Tu-160V bomber and the US Navy broke its own endurance record by keeping a fuel cell powered drone in the air over 48 hours by using a cryogenic tank for the liquefied hydrogen fuel. The German Navy also has an operational hydrogen fuel cell powered submarine.

Massive adoption of OTEC which has the potential of 262,800 terawatt hours of clean ocean power would provide the world's navies with a new mission, protecting the vital energy infrastructure.

August 31, 2013    View Comment    

On Energy From Oil or Energy From Water?

Cliff, I subscribe to the Roger Pielke Jr., Richard Smalley school that suggests we will need more energy in the future. All non-renwables produce heat as a byproduct of energy production. To produce Smalley's 60TW from fission or fusion you would produce 120TW of waste heat most of which would end up back in the ocean. OTEC would convert 60TWh to 60TWe and thus instead of adding 330 TWh to the oceans each year as a NOAA study suggests is the recent case you now are adding 270TWh. With fission or fusion that would be adding 450TWh so I submit OTEC is a significant improvement and I don't see wind or solar doing that much for the ocean heat problem.

With regards the surface cooling. This is pretty much what has been going on the last decade or so in the Pacific as the heat has gone into the deep. As most point out however this heat won't stay there it will return through convection and when it does global warming will resume and perhaps accelerate. Best I think to convert this heat to work?

August 30, 2013    View Comment    

On Energy From Oil or Energy From Water?

Robert the oceans are warming in any case - they are accumulating over 90 percent of the heat attributed to global warming. OTEC converts heat to work in accordance with the First Law of Thermodynamics thus it is the only way you can get this heat out. It also however moves about 25 times as much heat as work produced to the deep water. It would therefore sap the surface heat that drives tropical storms that move tropical heat to the poles causing the melting of icecaps and permafrost which again is a significant methane problem. The counter-current heat transfer system I propose limits the amount of heat dumped to the depths, which in turn maximizes the amount of power you can get out of the ocean. Again this is the only way you get the heat out of the ocean. OTEC is zero emissions energy and thus provides the opportunity to roll back global warming, hopefully in time to prevent the methane burp or slow emissions from below the East Siberian Sea projected by Cambridge and Rotterdam researchers over the next 30 years which would cause $60 trillion in damage.

August 30, 2013    View Comment    

On On Energy Subsidies and Externalities

The facts about energy subsidization: “On a post-tax basis which also factors in the negative externalities from energy consumption subsidies are $1.9 trillion (2½ percent of global GDP or 8 percent of total government revenues).the International Monetary Fund,

The top three subsidizers across the world, in absolute terms, are the United States ($502 billion), China ($279 billion), and Russia ($116 billion).

The market couldn't be much more distorted.

August 28, 2013    View Comment