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On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

Alistair a couple of colleagues are very interested in salinity gradient solar ponds as a way to jackup the efficiency of these kinds of systems. You can google them and and get all kinds of hits. They can get the temperature differential up to close to 100 degrees as I understand it.

I am kind of a purest and believe there is more than enough heat in the oceans already causing us grief and that simply relocating the worst of it into the deep would solve most of our problems.

 

 

February 6, 2015    View Comment    

On The Defeat of Climate Denial

"The policy debate will now shift from a discussion of the existence of the problem to one focused on solutions."

Hopefully that will be the case. In that event the potentially least cost energy solution, with the highest rate of environmental return stands a reasonable chance.

February 4, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

Robert, most of my associates prefer ammonia as the energy carrier. I don't know which is the best way to go. My main interest is in coverting warming heat to productive use. It seems to me though the auto industry has made a committment to hydrogen, where I don't see the same for ammonia, so I would think that would be the way to go. No doubt avoiding electrolysis would be more efficient but the best OTEC sites are pretty remote.

February 1, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

Hops locally there is a company that does what they call geo exchange. It pretty much works as you describe for all kinds of heat sinks.

February 1, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

Hops I'm not sure about that. In the past when CO2 concentrations were near 400 ppm the temperatures at the poles were close to 15C warmer, while the global average was more like 5. That being the case it doesn't seem to me the poles are acting much like a radiator.

February 1, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

Hops the coefficient of thermal expansion of ocean water at 1000 meters depth and 4C is half what it is a the tropical surface.

Further those storms move heat from the tropics towards the poles where it melts the icecaps, which is of course where the real threat from sea level rise exists. If this heat is moved instead into the deep where it warms that water only a few fractions of a degree, I submit the threat of sea level rise is greatly reduced.

Levitus et al determined that over the period 1955-2010 that the oceans to a depth of 2000 meters had warmed by only .09C. But were this heat released to the lower 10 kilometers of the atmosphere it would be instantly warmed by 36C. I think therefore it is pretty clear this heat, which isn't radiating to space in any case because it is trapped by the greenhouse blanket is best relocated to the deep.

 

February 1, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

If hydrogen can be stored in 600 bar tanks in vehicles, it can be transported in ships. PNG ships transport gas at 250 bar. When produced by electrolyzers situated at a depth of 1000 meters hydrogen would arrive at the surface pressurized to 100 bar.

High-pressure electrolysis is the most efficient way to do the job.

Compressed or liquified isn't the only way hydrogen can be transported. The Japan-based classification society ClassNK, has granted Approval in Principle (AIP) to a new H2/CO2 FPSO (floating production, storage and offloading) design developed by Mitsubishi Heavy Industries (MHI) and Chiyoda Corporation. It uses a new organic chemical hydride method to convert hydrogen into highly stable methylcyclohexane (MCH), which can be stored in liquid form at an ambient temperature and pressure.

This is probably not the last word on this problem either, considering the effort being put forth by the auto industry to transition to hydrogen.

January 31, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

The question is where are you going to invest the next infrastructure dollar? Where it will continue to damage the planet or where it will make things better for your grandchildren.

 

January 30, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

Nathan with technologically-based energy sources as with commodities what matters is cost. I don't see that it matters much whether the energy comes from a domestic or imported source or what you use to power your transportation, The Saudis are demostrating that pretty clearly at the moment. Since it is clear we have to get off fossil fuels, the lowest cost energy will be the winner in that case as welll, Based on the data in the Muralidharan paper I think the case can legitimately be made that OTEC, in the right configuration, can be the lowest cost energy. And when you couple that with the benefit derived from moving ocean heat into the depths the case becomes even more compelling.  

January 30, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

The heat pipe design has never been tested because the pressure exerted on pipes containing condensing vapor at depths of 1000 meters (100 bar) has been assumed to be sufficiently high that the thicknesses of condenser tubing required to prevent crushing would hamper the transfer of heat to the heat sink and thus the ability of the system to produce energy. Carbon dioxide however changes phase from a liquid to a volume and back at relatively high pressures - about 50 bar - in the 4 to 30oC temperature range that would be involved with these systems. Using CO2 as a working fluid therefore reduces the thickness requirement for tubing and thus improves the thermodynamics as well as allows for scaling of plants to sizes that would be economically unrivaled.

As to sizes of the heat pipe they would be between 1 and 2 meters diameter for a 100MW plant as opposed to 10 meters for the cold water pipe design.

I have some conceptual drawings for this kind of system at http://www3.telus.net/gwmitigationmethod/100MWPlant.htm

January 30, 2015    View Comment    

On The Lowest Cost Renewable Energy Comes With a 2000 Percent Environmental Dividend

Those electrolyzers working at full capacity produce hydrogen for on demand use without the necessity for excess capacity available only to meet peak loads.

The EnergyIsland Group also produced the following map showing how the electricity needs of the planet can be met with near shore OTEC plants and HVDC grids.

 

January 29, 2015    View Comment