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Carbon sequestration takes center stage in the campaign against global warming

WASHINGTON - Between a resurgent Democratic Party in Congress and the remarkable Al Gore, global warming has acquired a new cachet in America that has brought a myriad of doctors to its doorstep, offering more or less credible cures for atmospheric carbon dioxide emissions that many believe are slow-roasting the climate.

Carbon sequestration took the stage May 1 before a House of Representatives subcommittee on energy and natural resources. And like a number of the latest hopes, such as the esteemed Stern Review out of England, with its impassioned commitment to turning market economics against global warming through so-called cap-and-trade carbon offset regimes that limit carbon production by spreading around the energy production penalties incurred by companies that comply with carbon reduction standards, close examination revealed reason to believe the court must still be considered out, if not on global warming then on the suite of leading responses. The cap-and-trade carbon offset approach seems reasonable enough, given that a vast tonnage of carbon dioxide invades the atmosphere through coal-powered production processes and fossil fuel consumption. But cap-and-trade schemes in particular carry a baggage of concern that they will most certainly damage developed-country economies without reducing carbon dioxide emissions worldwide, especially given the risible regulatory standards in monster carbon-emission nations such as China.

Carbon sequestration refers to the long-term purposeful isolation of carbon dioxide from the atmosphere, so that it can't affect climate. It depends on the fact that carbon dioxide stores for long periods in natural elements without releasing into the atmosphere. Loosely used, the term can refer to countless everyday objects that harbor carbons, from graphite pencil lead to a sheet of paper.

But in practice, the reference is usually to either terrestrial carbon sequestration or geologic carbon capture and sequestration.

Terrestrial carbon sequestration relies on new-growth forests to contain carbon dioxide, or CO2, through photosynthesis. Beloved by environmentalists and a candidate for mass appeal as these things go, terrestrial carbon sequestration is, however, no silver bullet against global warming. Testifying before the House subcommittee May 1, William H. Schlesinger, dean of the Nicholas School of the Environment and Earth Sciences at Duke University, firmly relegated terrestrial carbon sequestration to one place in a suite of approaches. In brief, short of growing Texas-sized new-tree plantations and preserving them against economic use, just about any widespread effort to sequester carbons in trees and biomass involves a competing release of carbons from other sources and processes - much as industrial-scale ethanol production, for instance, tends to transfer energy expenditure from oil to other resources with little overall energy savings.

That leaves geologic carbon capture and sequestration as ''the critical enabling technology that would reduce CO2 emissions significantly while also allowing coal to meet the world's pressing energy needs,'' according to Howard Herzog, principal research engineer at the Massachusetts Institute of Technology Laboratory for Energy and the Environment. With the proper equipage and regulation, power producers can capture carbons and inject them in pockets and seams beneath the earth's crust. The energy industry is getting to like it because enhanced oil recovery, as a leading geologic carbon capture and sequestration process is known, can prolong the productive life of oil fields and mitigate emissions. But it is entirely, at this time, a product of private sector commercial enterprise, Herzog said, ''with the science coming as an afterthought.''

Not only has social concern grown up as to the unintended consequences of impregnating the undercrust of the Earth with carbon dioxide for the long haul, but a patchwork market approach risks economic consequences that could mimic the setbacks visited on wind power in the United States by market failures at the turn of the century. Wind power will recover, but the widespread concern of the day is that global warming advances at such a pace that any major setback to geologic carbon capture and sequestration will be unforgiving.

''We do not need to demonstrate we can inject CO2 into the ground,'' Herzog said. ''We are already doing that. Instead, we need demonstrations with full monitoring, integrated where possible, to lay the groundwork for large-scale deployment.''