"We're borrowing money from China to buy oil from the Persian Gulf to burn it in ways that destroy the planet. Every bit of that's got to change," Al Gore.
Changing the energy paradigm is the way America can create the capital-intensive jobs it needs to maintain a high standard of living and the country is rich in the skills required.
Hundreds of millions of people around the world have recently been lifted from poverty, with billions hoping to follow. To give 10 billion people, as is the projected population by the year 2150, the level of energy prosperity America consumes, a couple of kilowatt-hours per person, an additional 60 TW of power would have to be generated around the planet.
The total annual world energy consumption in 2006 for all primary energy sources was 15.8TW yet as Mr. Gore points out, the climatic effects of producing this amount is already seriously damaging to the planet.
The reason is thermodynamics. Any time energy of low-entropy is used to do work it is converted into high-entropy heat energy, which heats up some part of the Earth. An example is nuclear energy which many consider sustainable yet has a thermal efficiency of only about 33 percent, so reactors produce twice as much heat as electricity.
The First law of thermodynamics dictates that, "the increase in the internal energy of a system is equal to the amount of energy added by heating the system minus the amount lost as a result of the work done by the system on its surroundings."
The secret is then to find available heat, preferably in abundance, which can be put to work to generate the energy required.
The greatest source of
terrestrial energy is the sun and its greatest terrestrial storehouse is the
ocean with the downside of this thermal buildup being thermal expansion of the
oceans, melting of polar icecaps and the potential for increasingly forceful
hurricanes.
A recent Nature
article, "Robust warming of the global upper ocean" points out that the
average amount of energy the ocean has absorbed over the period 1993 to 2008 is
enough to power nearly 500 100-watt light bulbs for each of the roughly 6.7
billion people on the planet. This amounts to 330 TW compared to the 15.8TW
used in 2006.
As Charles H. Greene Director,
Ocean Resources and Ecosystems Program, Department of Earth and Atmospheric
Sciences, Cornell University, and others recently noted in a paper, A
Very Inconvenient Truth, due to the ocean's thermal inertia this build up
of energy in the ocean makes atmospheric warming essentially irreversible for
the next thousand years even if we immediately stopped adding CO2 to the
atmosphere.
This accumulating ocean heat can to put to work producing electricity by means
of the ocean thermal energy conversion method or (OTEC).
An interesting parallel has been drawn by Robert Cohen, who headed the US federal ocean thermal energy program in the early 1970s, regarding the energy supply available from OTEC. "A temperature difference is analogous to a hydraulic head where each degree centigrade corresponds to 427 m of head. Thus, a temperature difference of 21C would correspond to having the water at a height of 8967 m if 100% conversion efficiency were attainable...Thus, a net 2.5% conversion efficiency would enable a height of 224 m to be attained... It is as if much of the world's ocean water were captured behind invisible "thermal dams" of significant heights."
There are currently three main drawbacks to this approach; cost, production of power remote from where it is needed and a perceived need to bring large volumes of deep, cold, water to the surface to condense vapors of the low boiling point fluid used in the heat engine.
To bring this remotely generated power to shore it can be converted by electrolysis to the energy currency hydrogen.
Besides lowering the oceans thermal inertia and thus its expansion, producing hydrogen in this manner reduces the velocity of sea level rise by converting a portion of its liquid volume to gas; only 1/9th of which, by weight, needs to be transport to where it is needed to be recombined with resident oxygen to produce both power and water.
Instead of costly, massive, cold water pipes to bring condensing cold water to the surface, the much smaller volume of vaporized ammonia should be pumped into the depths to be condensed thus overcoming a massive technical and environmental problem and lowering the cost of OTEC.
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