Tuesday, July 14, 2009

The Second Law and carbon capture & sequestration

Letter in this morning's Oz:
KEVIN Rudd won kudos in Italy for his recent announcement of substantial funding for the Global Carbon Capture and Storage Institute ("World spotlight on Rudd at chaotic forum”, 11-12/7). But has he been adequately advised that, based on important scientific principles, its main objectives probably cannot be realised at an economic cost?

Lest Rudd soon be required by his advisers to defy gravity by walking on water, he should be aware that the technologies required for carbon capture and storage all involve processes profoundly at odds with the second law of thermodynamics. First, Boyle’s law and the associated formula for calculating pressure-volume work tell us that capturing, cooling and compressing carbon dioxide to the liquid form will need a significant proportion of the energy yielded by burning the coal in the first place.

Second, transporting the liquefied carbon dioxide at least three times heavier than the original coal used to generate it will add significantly to the energy cost—requiring even more fossil fuel. Finding suitable storage sites nearby to power stations for more than a small fraction of the total coal and oil we burn seems exceedingly unlikely.

Third, the ongoing cost of adequate monitoring and managing the containment of the geo-sequestered carbon dioxide, even for the next thousand years, could soon exceed the net value of the energy gained in the first place. Such concentrated storages of carbon dioxide will sooner or later demonstrate the dispersive power of the second law of increasing entropy when simple diffusion and other phenomena on a geological time scale such as earthquakes ultimately release the carbon dioxide to the atmosphere.

Finally, there is the doubtful morality of transferring the cost of dealing with such future catastrophes to succeeding generations, who will hardly thank us for our short-sighted and selfish solution in so fouling the earth’s mobile crust with a greenhouse gas.

Placing all our hopes in this flawed technology would be all the more tragic given the fact that that there are legitimate and sustainable alternatives, because nature has long provided biological carbon capture from the atmosphere using sunlight and water of extremely low cost compared to geo-sequestration. By using photosynthesis instead to capture carbon dioxide the second law would become entirely our ally.

Ivan Kennedy
Professor in Agricultural and Environmental
Chemistry, University of Sydney

Though I'm not sure if any of this would bother environmentalists. As I've detailed at length, their "solutions" to most problems relating to the use of fossil fuels and the like is to promote schemes that use more energy to create less, and at higher cost.

Posted via email from Garth's posterous

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