Sunday, January 11, 2009

Clean Coal Technology

It is easy to confuse the publicity with the reality. There is no clean coal plant today, but one could be built. Syngas made from coal would be far cleaner than simply burning coal, and there would be no fly-ash. (Actually there are a few plants --see this later post for clarification.)

I was annoyed to see "Exposing the Myth of Clean Coal Technology" on today. Bryan Walsh, the author, seemed to confuse the actual clean coal technology with putting scrubbers on a conventional plant.

Syngas made from coal, or coal gasification plants would make power as clean as we have a desire to make it. It would provide an easy way to separate carbon dioxide -- although someone has to solve the problem of where to put the enormous amounts of carbon dioxide involved. The diagram below, which is far too complex, shows the process. One can take any carbohydrate feedstock, bake it at high temperature without oxygen, and gasify it. One can burn the resulting gas like natural gas, or one can separate out the carbon dioxide first. One could also separate out all the hydrogen, and use it to make electricity in a fuel cell.

You can find more information on gasification on the DOE website. Although there is one gapping error on the site: they claim there are commercial plants, and there simply are not commercial plants for power production. There are some much smaller plants owned by Sasol in South Africa and some owned by Eastman Chemical in Tennessee. There were also power plants during World War II, and in South Africa during its embargos, but there is no production for power today.

The advantage of gasification of coal is that the carbon dioxide could be separated prior to burning the fuel. Once coal is gasified, it is a better fuel than natural gas.

There are many problems with coal gasification, but it is the real clean coal technology -- not putting scrubbers on a coal burning plant. The chief problem is a large-scale plant built so we can assess the technology. Someone needs to build the first one.