From: Spudboy100@aol.com
Date: Tue Sep 10 2002 - 06:14:42 MDT
http://news.bbc.co.uk/2/hi/in_depth/sci_tech/2002/leicester_2002/2248707.stm
UK geologists say efforts to bury the carbon dioxide byproduct from gas
exploration in the North Sea have been hugely successful. An experiment has
been running in the Sleipner Field since 1996, in which waste CO2 that comes
up with the extracted methane is separated off and then pumped back under
ground. It would normally be vented into the atmosphere. We believe it is
safe; it is certainly technically feasible and really has very little
environmental downside
Dr Andrew Chadwick
Dr Andrew Chadwick, from the British Geological Survey, says his work shows
the CO2 remains trapped in a giant bubble under a cap of shale and mudstone
almost a kilometre under the seabed. It has been suggested that carbon
sequestration, as it has become known, could be a practical tool that allows
humans to keep using fossil fuels without contributing to any global warming
effect. It could become normal practice not just for oil and gas companies
but electricity generation companies as well. It is possible that power
stations could collect their CO2 for storage and burial.
'Technically feasible' "If we wish to stabilise atmospheric concentrations of
CO2 at present levels, we will have to reduce emissions to zero in the next
50 years," Dr Chadwick told the BBC. "And carbon sequestration is probably
one of the most powerful techniques we have in that time for reducing those
emissions. "We believe it is safe; it is certainly technically feasible and
really has very little environmental downside." The experiment, run under the
direction of the Norwegian Statoil company, uses established technology to
separate out the 9% CO2 "impurity" in the methane. This is then sent back
down, in the form of a fluid that is just lighter than water, into an
800-metre-deep layer of porous sandstone. So far, Statoil has returned five
million tones of CO2 to the sub-surface rocks in this way.
Expensive option Seismic imaging conducted by Dr Chadwick shows the plume of
CO2 is behaving normally and is not leaking. In the last two years, it has
reached the top of the reservoir. The bubble has a lateral extent of about
1.7 kilometres. Separating CO2 from methane in a gas field is relatively
straightforward. The great prize would be to find an inexpensive and
practical technique for scrubbing the emissions from power stations. "There
are major cost implications," Dr Chadwick said. "The overall efficiency of a
modern gas-fired power station would be substantially reduced. "Also, you'd
have to find suitable locations to store the carbon. There are plenty of
locations in the North Sea - the obvious locations are exhausted oil and gas
fields which have proven ceiling capacity where we know gas cannot easily
escape from."
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