Geoscience Reference
In-Depth Information
incentives to do so. Nevertheless, the post-combustion capture process
includes proven technologies that are commercially available today.
Pre-Combustion Capture
This process separates CO
2
from the fuel by combining the fuel with air
and/or steam to produce hydrogen for combustion and a separate CO
2
stream
that could be stored. The most common technologies today use steam
reforming, in which steam is employed to extract hydrogen from natural gas.
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Oxy-Fuel Combustion Capture
This process uses oxygen instead of air for combustion and produces a
flue gas that is mostly CO
2
and water, which are easily separable, after which
the CO
2
can be compressed, transported, and stored. The U.S. Department of
Energy's (DOE) flagship CCS demonstration project, FutureGen, plans to
retrofit an existing power unit with an oxy-fuel combustion unit.
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CO
2
T
RANSPORT
Pipelines are the most common method for transporting CO
2
in the United
States. Currently, approximately 4,100 miles of pipeline transport CO
2
in the
United States, predominately to oil and gas fields, where it is used for EOR.
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Transporting CO
2
in pipelines is similar to transporting petroleum products
like natural gas and oil; it requires attention to design, monitoring for leaks,
and protection against overpressure, especially in populated areas.
10
Using ships may be feasible when CO
2
must be transported over large
distances or overseas. Ships transport CO
2
today, but at a small scale because
of limited demand. Liquefied natural gas, propane, and butane are routinely
shipped by marine tankers on a large scale worldwide. Rail cars and trucks can
also transport CO
2
, but this mode would probably be uneconomical for large-
scale CCS operations.
Costs for pipeline transport vary, depending on construction, operation
and maintenance, and other factors, including right-of-way costs, regulatory
fees, and more. The quantity and distance transported will mostly determine
costs, which will also depend on whether the pipeline is onshore or offshore,
