Clean coal is a term used to describe a process called ‘coal gasification’ and it’s totally different from the coal burning plants of your parents and grandparents generation. The clean coal advertisements and the excitement from the private industry, government agencies and the U.S. Air Force is for coal gasification. Currently, there are only seven clean coal plants in the U.S. employing coal gasification technology.
Coal gasification is very different from the old process called ‘pulverized coal’ that has been used at coal power projects for decades. The pulverized coal process burns pulverized coal in a large furnace. The process creates smoke and the hazardous substances are contained in the smoke. Many people incorrectly show pictures of pulverized coal plants spewing smoke when writing about coal gasification plants. It’s difficult and expensive to remove the hazardous substances from the smoke created by pulverized coal plants, because you only have one shot at it before it goes up the stack and into the atmosphere. With the pulverized coal process, the heat from burning the coal is used to generate steam and power steam turbines to generate electricity.
Coal gasification is much different. The coal gasification process operates in a closed system of equipment and piping and at a much higher temperature. The coal is gasified instead of burned which means that it is converted to a gas stream. The gas stream is called synthetic gas (syngas), because it’s man-made from the coal. The syngas is never released up a smoke stack. Instead, it’s processed in a closed system of piping and equipment the way a refinery processes crude oil. The syngas can be cleaned of hazardous substances within the closed loop system. This means there is little or no danger of the uncleaned (raw) syngas escaping to the atmosphere the way smoke can go up a smoke stack.
The syngas can be processed (cleaned) to remove particulates, mercury, sulfur, CO2 and other hazardous substances. After cleaning, the syngas can be used power gas turbines to produce electricity. In addition, the syngas can be processed further to convert it to many useful chemicals like ammonia for fertilizer or hydrogen to be used for refineries to remove sulfur from crude oil products. The syngas can also be further processed further to produce ultra-clean diesel fuel, jet fuel and gasoline.
There are many benefits of using the clean coal process in the United States. The United States has the largest coal reserves of any country in the world including China. The syngas can be used to generate electricity, produce fertilizer, hydrogen removing sulfur from gasoline and diesel fuel, CO2 to be used for improving crude oil production and to produce ultra-clean diesel, jet fuel and gasoline.
