Re: [PEN-L] sequestration

[Eugene Coyle]

For electric power, the industry with the largest emissions, the process is very expensive and perhaps 15 years in the future before it is commercial on a limited scale. To sequester carbon emissions the first step is to build an IGCC plant -- that is, a plant that turns the coal into a gas, from which pollutants and carbon (legally, carbon is not yet a pollutant) can be stripped. The gas is then burned in a gas turbine power generator. That type of plant is not now beyond the experimental stage. And it is much more expensive than building a current state-of-the-art coal burning plant with the best available control technology (BACT). So carbon capture is the first step, prior to attempting to sequester it. Sequestration does seem feasible, under limited conditions, if the geographical requirements come together. To make this work, the power plant must be reasonably close to the coal fields, and then must also be proximate to a geological formation that will retain the carbon under pressure. The CO2 is pumped into, say, an old oil or gas field near or at the end of its producing life. If the fractured layer which held oil or gas is beneath an impermeable cap -- not unusual -- the carbon can be pumped down a bore and hopefully will remain there for a thousand years or so. The carbon pressurizes the old field and can lead to enhanced oil recovery. But of course it all depends on the absence of cracks or leaks. The oil industry has, for years, used CO2 injections to enhance oil recovery -- but without really worrying about eventual carbon leaks. I strongly disagree with Gar Lipow's view of where we are in the horror of global warming. Gar Lipow wrote: But by the time we phase out net CO2 equivalent emissions we will have a number of feedback cycles started - melted icecaps, reductions in the ability of the biosphere to absorb carbon and so forth. So we will probably need to do some sequestration in addition to reverse the damage we have done. No point in making the investment in deployment while we can still have less expensive reduction opportunities untouched - but we should invest in research. Because in the long term, we will need to replace (at a very high price) the services of the natural carbon sinks we have destroyed or reduced the effectiveness of. We are way beyond starting the feedback cycles -- they are NOT in the future, they are happening now. In today's (11/25/05) UK Guardian, under the headline "Sea Lever Rise Doubles in 150 Years," there is the following _expression_ of despair: According to Prof Miller, there is little chance of slowing the rising tide caused by global warming. "There's not much one can do about sea level rise. It's clear that even if we strictly obeyed the Kyoto accord, it's still going to continue to warm. Personally, I don't think we're going to affect CO2 emissions enough to make a difference, no matter what we do. The Bush administration should stop asking whether temperatures are globally rising and admit the scientific fact that they are, but then turn the question around politically and say: 'We can't really do anything about this on any kind of cost basis at all'," he said. So sequestration of CO2 at incremental power plants, beginning fifteen years from now, even if feasible and practical if expensive, is already much too late. Florida will be the size of Rhode Island in 100 years, and Rhode Island will be the size of Columbus, Ohio. Gene Coyle Les Schaffer wrote: Perelman, Michael wrote: The Wall St. Journal has an article about the prospects for burying C02. in water or soil? The idea always seemed like a non-starter to me. Does it really have any promise? and Gar Lipow wrote: And you can't be certain once you sequestered CO2 that it will stay sequestered. Science 9 September 2005: Vol. 309. no. 5741, pp. 1711 - 1713 DOI: 10.1126/science.1110700 Reports Rising Atmospheric CO2 Reduces Sequestration of Root-Derived Soil Carbon James Heath,1* Edward Ayres,1{dagger} Malcolm Possell,2 Richard D. Bardgett,1 Helaina I. J. Black,3 Helen Grant,4 Phil Ineson,5 Gerhard Kerstiens1 Forests have a key role as carbon sinks, which could potentially mitigate the continuing increase in atmospheric carbon dioxide concentration and associated climate change. We show that carbon dioxide enrichment, although causing short-term growth stimulation in a range of European tree species, also leads to an increase in soil microbial respiration and a marked decline in sequestration of root-derived carbon in the soil. These findings indicate that, should similar processes operate in forest ecosystems, the size of the annual terrestrial carbon sink may be substantially reduced, resulting in a positive feedback on the rate of increase in atmospheric carbon dioxide concentration. [snip] Nevertheless, this study clearly demonstrates that a mechanism exists that may drastically affect the potential for sequestration of new carbon in forest soils. Even small shifts in the carbon balance of forests could cause a large feedback on atmospheric CO2 concentration, given that the annual exchange of CO2 in the form of terrestrial photosynthesis and respiration is approximately 9 to 10 times as large as annual emissions from the burning of fossil fuels (3, 21). Our results suggest that the incorporation of root-derived carbon into stable, medium- or long-term forest soil carbon pools may be substantially reduced as atmospheric CO2 concentration exceeds 100 µmol mol^–1 above current ambient. This would have the potential to trigger a large positive feedback on the rate of increase in global atmospheric CO2 concentration and associated climate change. les schaffer