From: Mike Lorrey (mlorrey@datamann.com)
Date: Thu Apr 11 2002 - 16:53:07 MDT
http://www.lanl.gov/worldview/news/releases/archive/02-028.shtml
LOS ALAMOS, N.M., April 9, 2002 -- Researchers at the U.S. Department of
Energy's Los Alamos National Laboratory are studying a simple, cost
effective method for extracting carbon dioxide directly from the air
which
could allow sustained use of fossil fuels while avoiding potential
global
climate change.
The method would allow researchers to harvest carbon dioxide from the
air,
reducing buildup of the so-called "greenhouse gas" in the atmosphere and
allowing it to be converted into fuel. A Los Alamos-led research team
today
presented the topic at the 223rd annual meeting of the American Chemical
Society in Orlando, Fla.
"Fossil fuel supplies are plentiful, and what will limit the usage of
fossil
fuels is the potential climatic and ecosystem changes you may see as a
result of rising CO2 levels in the atmosphere," said Los Alamos
researcher
Manvendra Dubey. "If you can capture atmospheric carbon dioxide, then
you
limit the environmental impact of fossil fuels and you can continue to
use
them. We have come up with a way to capture and sequester the carbon
dioxide
that we are putting in the atmosphere. Our approach is particularly well
suited to capturing CO2 from numerous small sources such as automobiles
that
are largely being ignored."
While many scientists are working on capturing or sequestering carbon,
Dubey
and his colleagues' method differs because it works on a dilute stream
of
CO2 in the atmosphere as opposed to capturing more concentrated forms
found
in power plant exhausts. The method uses ordinary air with its average
carbon dioxide concentration of about 370 parts per million.
It utilizes the wind and natural atmospheric mixing to transport CO2 to
a
removal site, and it is the only means available to capture CO2
generated
from transportation sources and small, dispersed sources that account
for
nearly half of all carbon dioxide emissions.
The air is passed over an extraction agent, for example a solution of
quicklime, the active agent in some cement. As the air passes over the
extraction structure, the carbon dioxide in the air reacts with the
quicklime and becomes converted to calcium carbonate (limestone), a
solid
that forms and falls to the bottom of the extractor.
The calcium carbonate is then heated to yield pure carbon dioxide and
quicklime, which is recycled back into the extractor. The purified and
liberated carbon dioxide can then be sequestered as a gas by direct
injection into the ground or it could be reacted with minerals to form a
solid. Carbon dioxide gas also can be sold commercially to the
petrochemical
industry, which uses large quantities of it to extract fossil fuels. Of
course, because the process uses existing air, it does not need to be
located near any particular elevated source of carbon dioxide. It
captures
carbon dioxide from all sources by harnessing wind as a no-cost
transportation vector.
"The carbon dioxide comes to the facility on its own," Dubey said. "And
because treated air is discharged, the overall concentration of carbon
dioxide in the atmosphere gradually decreases over time. Using this
method
on a large enough scale, it may be possible to return atmospheric carbon
dioxide levels to pre-Industrial-Age concentrations. Given the
possibility
our climate system can change abruptly, this possibility is very
exciting."
Cost of the entire process is equivalent to about 20 cents per gallon of
gasoline a nominal cost when one considers the recent price
fluctuations
at gasoline pumps across the nation, Dubey said.
A typical extraction facility that could extract all current carbon
dioxide
emissions would require only an area of one square yard per person in
the
developed world. A facility of sufficient size could be located in arid
regions, since discharged air that is deficient in carbon dioxide could
have
consequences on nearby plant life.
Large expanses of desert would not be affected by the CO2 deficit
however,
and could provide the wide-open spaces necessary both for the facility
and
to allow the discharged air to become well mixed with the atmosphere
again.
The next step for Dubey and his colleagues is to use intense computer
models
to optimize the configuration of the extractor as well as design
alternative
chemicals for extraction.
Dubey's research colleagues include Hans Ziock, Scott Elliott and
William S.
Smith of Los Alamos; Klaus Lackner, formerly of Los Alamos and now also
at
Columbia University; and Pat Grimes of Grimes Associates of Scotch
Plains,
N.J.
Los Alamos National Laboratory is operated by the University of
California
for the National Nuclear Security Administration (NNSA) of the U.S.
Department of Energy and works in partnership with NNSA's Sandia and
Lawrence Livermore national laboratories to support NNSA in its mission.
Los Alamos enhances global security by ensuring the safety and
reliability
of the U.S. nuclear stockpile, developing technologies to reduce threats
from weapons of mass destruction, and solving problems related to
energy,
environment, infrastructure, health and national security concerns.
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