The US government is trying to bury something at its Teapot Dome oil field again. Not secret oil leases, as it did during an infamous scandal of the 1920s, but carbon dioxide -- lots of it.
In hopes of developing a process that could slow global warming, the Energy Department wants to inject the greenhouse gas underground into depleted oil reservoirs after converting it into a liquid form.
The Teapot Dome project, now in the planning stages, could be one of the world's largest test sites for the method. It would store carbon dioxide from a natural-gas processing plant more than 484km away beneath the 4000 hectare oil field in central Wyoming.
So-called carbon dioxide sequestration has been tested at smaller sites nationwide but never on such a large scale, said Vicki Stamp, a project manager for the Rocky Mountain Oilfield Testing Center, which manages Teapot Dome.
Used in enhanced oil recovery for decades, pumping carbon dioxide into underground reservoirs is being touted by the Bush administration as one of the most promising ways to counter the greenhouse effect.
"[Carbon dioxide] is the primary global greenhouse gas and it's growing rapidly," said Dag Nummedal, director of the University of Wyoming Institute for Energy Research.
"During the last four or five years the international consensus is that the most rational, economic and environmentally benign way of getting carbon dioxide out of the atmosphere is to store it underground.
"Right now, the best place to do this is in depleted oil and gas fields."
Teapot Dome -- named for a nearby rock formation -- is currently in its preliminary engineering and testing stages. Storage could begin by 2006 and last seven to 10 years, although Nummedal says managers "don't really know the upper limit yet."
Keep it sealed
When a reservoir is full, the pipeline is taken out and the hole sealed up. "The objective is to keep it sealed underground forever, hundreds or thousands of years," Nummedal said.
The site is projected to store at least 1.6 million tonnes of carbon dioxide a year when fully operational. It could eventually lead to large-scale testing in other Rocky Mountain states, the Ohio River Valley, Texas Gulf Coast, California and other areas, Nummedal said.
"The long-term plan is to encourage the growth of a new private sector sequestration industry," he said.
Talk of a national carbon dioxide testing center started early last year. But it wasn't until managers found a source of carbon dioxide later that summer that the idea became a reality.
Anadarko Petroleum Corp, which owns an adjacent oil field, is extending its existing carbon dioxide pipeline from a natural-gas processing plant in western Wyoming and has agreed to direct some of its 43 million cubic meters of carbon dioxide to the test site, Nummedal said.
The gas will then be pressurized and injected as a liquid into the reservoirs through a pipeline. It could stay underground for a very long time, since the reservoirs that would store the carbon dioxide held oil and methane gas for millions of years, said Susan Hovorka, a University of Texas researcher.
"That's not true of other mechanisms," she said.
"If you grow more [trees, which consume carbon dioxide] how do you assure it doesn't all go up in a forest fire or that another generation decides to go ahead and farm that area?"
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