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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    

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

Bas, you do not bring warmer, ligher water down to 1000 meters. A heat pipe works by boiling a working fluid, which creates a region of high pressure, causing the vapor to flow to a region of lower pressure where the vapor is condensing; releasing the latent heat of condensation into the 4°C water at depth, This heat movement takes place in a matter of seconds whereas it is estimated it takes as long as 350 years for heat at the oceans surface to diffuse to 1000 meters due to the bouyancy effect you describe.

The placement of a turbine in the vapor stream permits the production of power.

Sorry for the link, I believe it works now.

If I have failed to adequately describe this approach then clearly that is on me.

January 29, 2015    View Comment    

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

They are no further from their markets than Middle East oil is from theirs. The power would be converted to an energy carrier for transport as described in the paper.

January 29, 2015    View Comment    

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

The ultimate cost remains to be proven but the data from which it is derived is referenced in the paper as coming from Encana. The savings and environmental benefit are significant enough that the approach warrants investigation.

January 29, 2015    View Comment    

On 'Hottest Year' Story Obscures Bigger News: Ocean Warming Now Off The Charts

Scientists have long suspected that extra ocean heat uptake has slowed the rise of global average temperatures,"

Just as climate change is anthropogenic, ocean heat uptake can be induced by human enterprise, using heat pipes that utilize the phase changes of a working fluids to move trapped surface heat into the abyss in accordance with the 2nd law of thermodynamics that dictates also that such movements, through a heat engine, produce work. Researchers from the University of Hawaii have estimated the oceans have the potential to produce 14 terawatts of energy with ocean thermal energy conversion and due to the low thermodynamic efficiency of the process approximately 20 times more heat is moved from the surface to the deep in that process therefore virtually all of the heat the oceans have been accumulating as a result of global warming – estimated by NOAA in 2010 to be about 330 terawatts/year – can safely be sequester or converted to useful energy.

Not only does this approach slow the rise of global average temperatures, it is demonstrably the cheapest way to produce carbon-free energy.

The following table from the MIT masters thesis of Shylesh Muralidharan shows the high capacity factor of OTEC as well as its competitive levelized capital cost with respect to other technologies. (Although not shown in this table the paper points to a study that shows a deep water condenser architecture - the design that moves heat the deepest - can bring down the installed capital cost of a 100 MW plant ship from 4000 $/kw to 2650 $/kw.)


 
The thesis also shows that doubling plant size leads to a cost/kW reduction of OTEC plants by approximately 22%.

Using CO2 as a working fluid for the deep water condenser design allows for plants of gigawatt capacity.

Extrapolating for a 1 GW plant of the deep water condenser design, it would cost $86*2650/4000*78/100*(1-(.22*(200/800))) or 42 $/MWh for the lowest levelized capital cost for all energy sources but for combined cycle natural gas and would be the cheapest of all renewables.

It is this capacity to scale to low cost combined with the environmental dividends inherent in the production of energy from this source that makes it transformational as well as vital to the sustainability of the planet.

 

January 28, 2015    View Comment