Capping Carbon ; Looking for Ways to Contain the Gases from Fossil Fuels

Article excerpt

Over vast stretches of geologic time, earth has evolved ways to swap its treasure trove of carbon among various "accounts": the atmosphere, oceans, land surfaces - and even hoarded deep beneath its crust.

Yet since the dawn of the Industrial Revolution, humans have fueled their economies by drawing coal, oil, and natural gas from under the planet's mattress and burning them - boosting the rate at which carbon dioxide builds in the atmosphere and warms it.

Now, scientists and engineers are looking for ways to reverse the process and take carbon dioxide from fossil fuels out of atmospheric circulation. Ideas range from "fertilizing" vast patches of the ocean's surface so CO2-gobbling algae will grow faster to pumping the gas into underground rock formations or deep beneath the ocean.

The questions they hope to answer: Will these work? Will these remedies be cost-effective? And will they do more environmental harm than good?

"There is nothing wonderful about carbon sequestration," acknowledges Robert Socolow, a Princeton University engineering professor who specializes in environmental technology. But in battling climate change "there is no winner-take-all option. We'll need a mix of energy systems indefinitely at least through the 21st century."

This mix includes three broad paths toward reducing what a growing number of scientists see as humanity's impact on climate: using energy more efficiently; using energy sources that don't emit large quantities of carbon dioxide; and using fossil fuels, but keeping their carbon out of the atmosphere.

Of the three, sequestration represents "the new kid on the block," says Howard Herzog, a researcher at the Massachusetts Institute of Technology's Energy Laboratory and co-author, along with Dr. Socolow, of a 1999 US Department of Energy report on sequestration research.

The notion of sequestering or managing carbon from fossil fuels raises eyebrows among some environmental groups.

"The general problem we have is that this is an excuse to keep using fossil fuels," says Kert Davies, with the Greenpeace USA climate campaign.

In some cases, he acknowledges, separating carbon could be beneficial - for example, separating carbon from natural gas to leave hydrogen as a fuel, then pumping the carbon back underground as CO2. This could help provide a transition from a carbon economy to a hydrogen economy.

In other cases, he continues, carbon management "only derails us from our main course of action, shifting to a fossil-fuel-free world."

Yet to others, the argument for stripping carbon from fuels or from smokestack emissions is compelling.

David Wallace, who focuses on energy research and development at the International Energy Agency in Paris, notes that the carbon- reduction task the world faces is enormous. To "stabilize CO2 concentrations at twice their pre-industrial levels by the end of this century, developed countries will have to reduce their emissions to around half of the 1990 levels, or even lower," he concludes.

Storing carbon dioxide from power plants alone, he continues, could provide large and fast reductions on CO2 emissions and ease the transition from fossil fuels to alternative sources of energy.

Indeed, some economists note that for countries such as India and China, coal may be the most easily obtained and cheapest fuel available for decades to come. Sequestration technologies may be one way to minimize these nations' CO2 emissions.

Particularly since 1997, when a protocol for taking the first steps toward cutting CO2 emissions emerged from a United Nations conference in Kyoto, government and private funding for sequestration research has grown.

The US Department of Energy, for example, has put $15 million into sequestration research during the past two fiscal years and will spend another $18. …