Cleaner Burning Coal Technologies
October 2, 2002
Coal-fired power plants supply half of the electricity used in the United States but are responsible for 80 percent of the industries' emissions of carbon dioxide. Now that many older plants are nearing the end of their commercial lives, energy engineers are talking about replacing them with new plants utilizing "clean coal" technology.
However, clean coal means different things to different people. Ultimately, clean coal falls into three categories: 1) pre-combustion processing of coal, 2) combustion processes that burn coal more cleanly, and 3) post-combustion processes that scrub the exhausts.
Among the benefits of clean coal:
- A Denver-based company is processing dirty western coal into cleaner-burning coal with a 60 percent higher energy output.
- The most common method of cleaner coal is post-combustion scrubbing -- which is 95 percent effective at one-third of the cost of earlier technologies.
- A newer method, integrated gasification combined cycle (IGCC) power plants, are 20 percent to 33 percent more efficient than conventional power generation while having far fewer emission than is possible using scrubbers.
A handful of IGCC plants already exist around the world. In IGCC plants, coal is processed on-site into a gas, cleansed of pollutants and burned in a gas-fired turbine.
Proponents of clean coal have heralded its arrival before. What's different this time, they argue, is power producers themselves are investing in, funding and building commercial-scale facilities that burn coal.
Source: "Clean Coal's Uphill Haul," The Economist, September 21-27, 2002.
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