Energy and Changes in the Environment - Hydrogen and Fuel Cells: Advances in Transportation and Power - page 71

The Weyburn project began four years ago and has the backing of
international energy companies, the United States, European Union and
Canada, which have contributed $21 million.
In 1986, 1,700 people in West African Cameroon, suffocated when
a giant bubble of naturally occurring carbon dioxide erupted from Lake
Nyos and displaced the available oxygen in the immediate area.
Deep-well injection of the gas may force briny water to the surface,
potentially polluting streams and aquifers. Earthquakes have also been
reported in places where deep-well injection has occurred and carbon
dioxide can convert to an acid in groundwater. Carbon storage provides a
unique advantage, buried in an oil field, the gas boosts oil production by
forcing residual deposits to the surface. At Weyburn, oil production is up
50% since carbon dioxide injection began four years ago.
The Weyburn site was selected because, during 44 years of oil
exploration, Saskatchewan required oil companies to keep extensive
geological records. Core samples from 1,200 bore holes allowed an
extensive look at subsurface conditions and a way to track the movement
of oil and gases.
Carbon dioxide is injected almost a mile underground under a thick
rock layer. The buried carbon dioxide is tracked by checking vapors in wells
and groundwater testing. Seismic tests provide a picture of subsurface
conditions.
The site has hundreds of oil wells over a 70-square-mile area. Each
well shaft can act as a conduit to bleed carbon dioxide to the surface. Some
wells are being closed off while others are checked for traces of carbon
dioxide.
Computer models are being used to forecast how the site will perform
over several millenniums. One computer model showed that carbon
dioxide could migrate upward about 150 feet in 5,000 years although it
would still be far below the surface.
Every day, almost 5,000 tons of liquefied carbon dioxide arrives from
a plant near Beulah, N.D. This plant is operated by the Dakota Gasification
Co., which converts coal to natural gas. The liquid carbon dioxide passes
through a 220-mile-long pipeline before it is pumped underground in
Canada.
Separating the carbon dioxide is expensive since the scrubbing
process uses almost one-third of the energy produced by the power
plant. It costs about $30 a ton to separate carbon dioxide from industrial
exhaust, although the technology exists to cut this almost in half. One