By SHARON BEGLEY
Science May Discover the Hair
Of the Dog for Pollution Binge
Junk-food junkies have Tums. Hung-over party animals have cold compresses. Even shopaholics have the returns desk.
Because it seems to be human nature to indulge to your heart's content and expect to undo the damage the morning after, it may be inevitable that scientists and policy makers are wondering if the same approach might extricate civilization from the threat of global warming.
Ever since fossil fuels (coal, oil and natural gas) began powering industrial economies about 150 years ago, their combustion has been raising atmospheric levels of carbon dioxide (CO2), the invisible so-called greenhouse gas that traps heat and threatens to change climate for the worse.
The nations of the world aren't exactly racing to put a brake on carbon emissions. Even under the 1997 Kyoto Treaty -- ratified by 111 nations, but not the U.S. or enough of the other major polluters to put it into effect yet --atmospheric levels of CO2 could at least double from preindustrial levels by the end of this century.
"Kyoto does almost nothing to the big picture," says Eileen Claussen, president of the Pew Center on Global Climate Change. "To stabilize the atmosphere, you'd have to cut emissions by more than 60% from levels today."
That realization has led to an idea variously considered brilliant or nutty: If we can't kick the fossil-fuel habit, which today provides 85% of the world's commercial energy, let's suck up the CO2 that results.
Called carbon sequestration or storage, the idea dates at least to 1977, when a scientist came up with a scheme to inject CO2 into the Strait of Gibraltar. Apart from the intriguing image of turning the seas into giant vats of salty seltzer (CO2 provides the "carbonated" in carbonated drinks), this proposal has little to recommend it. Dissolving vast quantities of CO2 into the oceans could fatally change their chemistry.
A more viable option is under way in the oil fields of Texas. There, operators practice "underground injection" to coax out the last little bit of Texas crude: CO2 goes in, oil comes out. The wells are sequestering about 20 million tons of CO2 a year. Globally, oil and gas fields have the capacity to store as much as 300 billion tons, half the CO2 we would emit in the 21st century if emissions held at current levels, estimates physicist David Keith of Carnegie Mellon University, Pittsburgh.
Porous rock beneath oceans and continents could hold more than 10 times as much. Already, Statoil, of Norway, injects a million tons of CO2 annually into such "saline aquifers" beneath the North Sea. (Norway taxes CO2 emissions from off-shore oil production.) But that may turn out to be more temporary standing than permanent parking. The CO2 could increase pressures in the aquifer enough to widen fissures and escape.
To stabilize the atmosphere, the CO2 would have to stay put for centuries or more. So while engineers figure out whether leakage from geological storage would be a problem, they are also looking at another, probably more expensive, possibility. Reacting CO2 with crushed serpentine or olivine rocks would form carbonates or bicarbonates, solids that endure for millennia, says Klaus Lackner of Columbia University, New York.
Retrofitting power plants so their CO2 is captured before it wafts out the smokestack would be hugely expensive. It would be cheaper to retire old plants and replace them with models whose carbon is easily captured. But that requires a signal from policy makers or markets that they are serious about stabilizing CO2 in the atmosphere.
Capturing CO2 from cars, trucks, ships and planes is trickier. Trapping it on board is impractical: CO2 weighs three times what gasoline does. Instead, researchers are exploring whether the CO2 could be sucked out of the atmosphere. One possibility, says Prof. Lackner, is to blow air into enclosures housing chemicals that absorb CO2.
That is also the plan of last resort if CO2 levels produce a climate as stormy, overheated and drought-plagued as some models predict. "If the political will were there," says Prof. Lackner, "carbon sequestration could start tomorrow and be phased in over a few decades."
Sequestration has begun to gain appeal because CO2 is in no hurry to leave the atmosphere. An average molecule of the gas stays there for a century; CO2 belched out by Model Ts still circle the planet. Keeping CO2 at its current levels for this century will require slashing emissions by more than 60%. Some industry groups become apoplectic even at the notion of holding emissions constant, so that is a tall order politically.
"Carbon sequestration is attractive because it's one of the only options that offers the possibility of deep cuts in CO2, not just working at the edges as fuel switching and energy efficiency do," says geologist Sally Benson of Lawrence Berkeley National Laboratory in Berkeley, Calif.
Sequestration would let the world burn its massive reserves of coal, buying time until clean, affordable alternatives are ready. That makes some environmentalists wary of the idea, because it lessens pressure to move toward renewable energy. In fact, carbon sequestration on a large scale is at least a decade away, but because it could add 25 cents to the price of a gallon of gasoline, and a few cents to a kilowatt-hour of electricity, it could level the playing field, pricewise, for nonfossil fuels.