How does carbon sequestration work?

So, what's the problem?

The problem with carbon sequestration is the cost. But a paper by MIT economists Jeremy David and Howard Herzog concludes that, "with new developments, CO2 capture and sequestration can become a cost-effective mitigation pathway." In other words, wait a couple years for technology to catch up, and sequestration will not only be possible, but practical. Another report by the U.S. Department of Energy's Office of Fossil Energy details the costs in depth, showing that carbon capture and sequestration in geologic formations is possible from a coal power plant at only a 10 percent increase in the cost of energy, as long as the pipeline from plant to sequestration site is less than 50 miles (80 kilometers) long.