h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

"Carbon dioxide can (in theory) be removed either pre or post combustion..."

Just how do you remove the CO2 before you burn the carbon? Until you have combusted the carbon, there's no CO2 to remove.

To remove Carbon Dioxide pre-combustion you have to gasify the coal. Coal Gasification was used in the 20th and 19th Centuries to produce Town Gas, which in Britain was replaced by Natural Gas after reserves were found under the North Sea.

In a power station the Coal would be gasified by heating it in a low oxygen atmosphere to release Carbon Monoxide, steam can then be used to turn this into Carbon Dioxide and Hydrogen. These can be separated - possibly through using chemical scrubbers or other means - and the Carbon Dioxide Sequestered whilst the Hydrogen is burnt in a Gas Turbine.

One of the drawbacks of this method is the Hydrogen burning Gas turbine which I don't believe has yet been developed. Perhaps advances in fuel cells will encourage this method of Carbon Capture.