Geoscience Reference
In-Depth Information
mitigation option is overwhelming compared to the amount of CO
2
used
for EOR.
According to the U.S. Department of Energy (DOE), the United
States has the potential to store billions of tons of CO
2
underground and
keep the gas trapped there indefinitely. Capturing and storing the
equivalent of decades or even centuries of CO
2
emissions from power
plants (at current levels of emissions) suggests that CCS has the potential
to reduce U.S. greenhouse gas emissions substantially while allowing the
continued use of fossil fuels.
An integrated CCS system would include three main steps: (1)
capturing and separating CO
2
from other gases; (2) purifying,
compressing, and transporting the captured CO
2
to the sequestration site;
and (3) injecting the CO
2
in subsurface geological reservoirs or storing it
in the oceans. Deploying CCS technology on a commercial scale would
be a vast undertaking.
The CCS process, although simple in concept, would require
significant investments of capital and of time.
Capital investment would be required for the technology to capture
CO
2
and for the pipeline network to transport the captured CO
2
to the
disposal site.
Time would be required to assess the potential CO
2
storage reservoir,
inject the captured CO
2
, and monitor the injected plume to ensure against
leaks to the atmosphere or to underground sources of drinking water,
potentially for years or decades until injection activities cease and the
injected plume stabilizes.
Three main types of geological formations in the United States are
being considered for storing large amounts of CO
2
: oil and gas reservoirs,
deep saline reservoirs, and unmineable coal seams. The deep ocean also
has a huge potential to store carbon; however, direct injection of CO
2
into
the deep ocean is controversial, and environmental concerns have
forestalled planned experiments in the open ocean. Mineral
carbonation—reacting minerals with a stream of concentrated CO
2
to
form a solid carbonate—is well understood, but it is still an experimental
process for storing large quantities of CO
2
.
Large-scale CCS injection experiments are only beginning in the
United States to test how different types of reservoirs perform during CO
2
injection of a million tons of CO
2
or more. Results from the experiments
will undoubtedly be crucial to future permitting and site approval
regulations.
Acceptance by the general public of large-scale deployment of CCS
may be a significant challenge. Some of the large-scale injection tests
could garner information about public acceptance, as citizens become
familiar with the concept, process, and results of CO
2
injection tests in
their local communities.
