Mon, Feb

Geologists Compress, Bury Carbon Dioxide Beneath Texas Oilfield in Experiment

Some Texas geologists believe the best way to get rid of the carbon dioxide produced by burning fossil fuels is to simply put it back where it came from.

Oct. 5—Some Texas geologists believe the best way to get rid of the carbon dioxide produced by burning fossil fuels is to simply put it back where it came from.

Monday, scientists began burying 3,000 tons of compressed carbon dioxide 1 mile beneath an old oil field near Dayton. If the plan works, most carbon dioxide — a greenhouse gas — could be captured from area smokestacks and stored harmlessly underground, not pumped into the atmosphere.

"We're going to test every aspect of this to determine whether it is safe," said lead researcher Susan Hovorka, with the University of Texas at Austin's Bureau of Economic Geology.

So-called carbon sequestration is not a new idea. Scientists have experimented with storing the gas on the ocean floor and thousands of feet below ground.

Norway has already buried nearly 70 million tons below the North Sea in the space where it had extracted fuels.

Annually, man-made sources of carbon dioxide emit 7 to 10 billion tons of the gas.

Capturing a major chunk of those emissions, and storing them deep below ground, could ease global warming problems, scientists say, while giving the world time to move away from fossil-fuel dependency.

The effort by UT geologists, in conjunction with scientists from other labs nationwide, is the first major attempt to determine whether the sandstone layer beneath the Texas and Louisiana coasts makes a good carbon dioxide reservoir.

For the next two weeks, trucks from Baytown and Louisiana will deliver compressed carbon dioxide to the site in Liberty County. Using a modified oil well, the researchers will pump the gas into sandstone deposits 5,050 feet below ground.

There the gas — so compressed it is almost a liquid — soaks into the sandstone and saltwater, like bubbles in Coca-Cola, Hovorka said.

Among the team's concerns is that too much pressure may cause the shale layer atop the sandstone to crack, or might even cause a small earthquake. But Hovorka said such problems can be solved by closely monitoring the pressure where the gas enters the ground.

As for leaks, the research team has calculated that just 1 percent of the gas will seep into the atmosphere after 300 years.

The group has chemically "tagged" the gas they are burying so they can measure if any returns to the surface in the coming weeks and months.

Seepage not a threatEven at relatively high concentrations, carbon dioxide is not harmful. After all, anyone who drinks a carbonated beverage inhales it.

And now the gas is simply being dumped into the atmosphere, so a little returning to the surface poses no danger, Hovorka said.

Environmentalists said the plan is worth pursuing.

"If it's something that can be done reliably and safely, then this is one way to mitigate against the impact of greenhouse gas emissions," said Ramon Alvarez, an atmospheric scientist in the Texas office of Environmental Defense.

Should burying the carbon dioxide below ground prove safe and reliable, the next hurdle will be cost, scientists say.

Removing carbon dioxide from fossil fuel fumes would be expensive, as would building the infrastructure to transport the gas below ground. But Hovorka said the price tag would not be exorbitant.

For pennies on the dollar more than current electric rates, she said, people could use fossil fuels with cleaner air and consciences.

Requirements of successful carbon sequestration:
—Reliability: Be effective and cost-competitive.
—Storage: Provide stable, long-term storage.
—Safety: Be environmentally benign.
Source: U.S. Department of Energy

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