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  Clean Coal Technology
Electric co-ops and others are investing in fuel for the future

John S. Mead Director of the Southern Illinois University
Coal Research Center.

Coal has been at the center of technology development in America for the better part of two centuries. It fueled a manufacturing and transportation revolution in the 19th century and provided the power to help electrify the 20th century. In the future we will need coal to make clean electricity, plus the essential fuels and materials now produced from petroleum and natural gas. Advanced technology, clean coal technology, is making such a future a reality.

For the most part our connection to coal is through wires that deliver electric power. The power plants that turn coal into electricity have been transformed over the past century, but the basic process has really not changed. Heat produced from the combustion of coal turns water into steam and the steam runs an engine that turns an electric generator. By the 1960s this simple concept had evolved into the giant central generating stations that we see today in Illinois and across the country. These conventional power plant designs are among the most proven and reliable industrial systems ever built; however, by the 1970s a dramatic new demand was placed on this tried and true design: air pollution control.

The first and still most common clean coal technologies are systems that clean up the flue gasses (the exhaust) from conventional coal fired electric power plants. Several pollutants have been regulated since the early 1970s, including: particulates, sulfur dioxide and nitrogen oxides. Sulfur dioxide removal systems (known as flue gas desulfurization or scrubbers) have always been the best known and most controversial technologies because of their high cost and because power plant owners could sometimes avoid their use by switching to lower sulfur content coals.

An excellent example of flue gas desulfurization, nitrogen oxides and particulate controls at work in Illinois is at Southern Illinois Power Cooperative’s Lake of Egypt station. The ultimate conventional power plant with flue gas cleanup may someday be the Prairie State Energy Campus now in planning and permitting. This project will bring together all of the latest developments in the evolution of conventional power plants, plus flue gas cleanup.

As flue gas cleanup was being introduced to the power industry in the 1970s, a different approach was being developed: Fluidized Bed Combustion (FBC). FBC combines the desulfurization step with the combustion process. Like the operation of a combine in harvesting, the FBC system does multiple operations in a single device. This clean coal technology offers excellent sulfur dioxide reduction in a somewhat simpler, smaller package. These plants can also accommodate a wide range of solid fuels, making them attractive for fuel mixtures of coal and biomass. The latest coal fired power plant in Illinois is an FBC unit that is also located at Southern Illinois Power Cooperative’s Lake of Egypt station.

A process known as gasification is emerging as an exciting alternative to both combustion systems and as a way of extracting valuable synthetic fuels and materials from coal. Gasification is a technique that uses heat and pressure in a controlled system to break coal down into a variety of chemicals that can then be processed into a wide variety of products.

Primitive gasifiers were used to make town gas in past generations. Today coal gasification offers a highly efficient way to remove essentially all pollutants.

A gasification plant can be designed to make fuels and other products that we now produce from petroleum or natural gas. Gasification is efficient and flexible, but it has another capability that may be of enormous importance: we may be able to produce a carbon free fuel (hydrogen) and keep the carbon from the coal out of the atmosphere. This will be a great leap in clean coal technology and could be part of a global strategy to address climate change issues. The FutureGen project will demonstrate just such a technology, along with the control of virtually all other pollutants.

 

More Information

John S. Mead, Director of the Southern Illinois University Carbondale Coal Research Center.
The Center facilitates coal and related energy and environmental R&D across many campus departments and programs.