28-01-04
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 CO2 from a natural gas
processing plant more than 300 miles away beneath the 10,000-acre 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 Centre, 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 CO2 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
7 to 10 years, although Nummedal says managers "don't really know the upper
limit yet." 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 mm tpy of carbon dioxide 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 CO2 testing centre 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, which owns an adjacent oil field, is
extending its existing CO2 pipeline from a natural gas processing plant in
western Wyoming and has agreed to direct some of its 125 mm cf of CO2 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 CO2 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?" Burial can also rid the Earth of a large volume of carbon dioxide in
a relatively short amount of time, Hovorka said.
"We've got almost all the carbon dioxide emitted in the atmosphere coming
from fossil fuels," she said. "There's space equivalent in acreage to
put all that carbon dioxide back underground."
If the project pans out, officials hope to capture CO2 from the nation's power
plants, oil and gas refineries and other manufacturing facilities "because
that is the CO2 today that is leaking into the atmosphere without any controls
on it," Nummedal said. One possibility is capturing the gas with scrubbers
similar to those attached to smokestacks that remove nitrous oxide and other
gases, he said.
The storage process -- particularly compressing the CO2 -- is expensive. Some
estimates put it as high as $ 100 per ton, though Nummedal and others said they
don't yet have cost estimates for Teapot Dome. Even if it is a success, the
Teapot Dome project could have little impact by itself.
"Globally we are releasing 7 bn tons of carbon per year," Nummedal
said. "The amount we will be putting away here will be in the hundreds of
thousands of tons."
But he added: "If we look at all the suitable, depleted oil and gas
reservoirs in the world, and we were able to fill all of them up, we would be
able to store the total global emissions over the next 100 years."
Some environmentalists worry about gas bubbling through cracks in the Earth
or leaking into aquifers that supply drinking water.
"We very clearly need some field demonstrations of a storage system to make
sure (we) don't have any surprises," said David Hawkins, director of the
Natural Resources Defence Council's Climate Centre in Washington, DC Nummedal
and others stress they're testing Teapot Dome reservoirs for those concerns.
"The early steps of this cooperative venture show the classic markings of a
win-win proposition for American consumers," Energy Secretary Spencer
Abraham said.
Source: The Associated Press