Energy Biz - September/October 2008 - (Page 90) (Guest » technoloGy Frontier the Lure of Ultra-Supercritical ExPLORiNg THE FUTURE OF COAL-BURNiNg By WiLLiAM L. SigMON coal. iT’s The fuel people loVe to hate. Coal generates more than half of the electricity in the United States. It’s used in baseload generation supplying some of the nation’s least-expensive electricity. It’s the most plentiful fuel source in the United States, enough to last more than 200 years at today’s level of use. It’s one of America’s strategic energy advantages. But burning coal emits carbon dioxide, a greenhouse gas, into the atmosphere at a time when climate change is a significant issue. Rational people admit that coal must remain an important part of the nation’s fuel mix to avoid potentially devastating economic consequences. The same rational people express concern about climate change. It creates a difficult equation. Use less coal, but keep electricity affordable by not reducing the amount of electricity produced with coal. And reduce greenhouse gas emissions. With the United States needing new baseload generation to replace higher-emitting plants nearing retirement and to supply the continued growth in the nation’s demand for electricity, it’s an equation that requires an immediate solution. It requires new technologies. American Electric Power and others are advancing technologies to capture NewsFlash and store carbon dioxide south aFRiCan shiFt emitted from existing and South Africa is turning new coal-fired plants, but from coal generation to widespread implementation nuclear and renewable power, according to a of these technologies is up report by the Associated to a decade away. Press. Coal has generated Advanced coal-fueled about 90 percent of generating technologies South African electricity. Marthinus van provide a more immediate Schalkwyk, the solution for use in new environment minister, said, “We are saying to baseload generation today. business and society AEP is a vocal advocate of at large that we have to two such technologies. move away from dirty coal as a dominant One — integrated-gasifienergy source.” cation combined-cycle, or The cost of generating electricity IGCC — receives the most from coal in South Africa attention. Its precombustion is lower than most other areas of the world. chemical process, convertSeptember/October 2008 OpiniOn) ing coal into a synthetic gas while removing impurities, is a radical change from coal-fired generation in use today. In AEP’s view, IGCC is the best solution for new generation using the higher-BTU coals mined in the eastern United States. But ultra-supercritical pulverized coal technology represents an equally important advancement, especially for areas relying on lower-BTU coals from the Powder River Basin. AEP has received regulatory approval to build a 600-megawatt ultra-supercritical plant in Arkansas and, as of this writing, is waiting for the necessary environmental permit to begin construction. This will be the first ultra-supercritical power plant in the United States. An ultra-supercritical coal-fired plant consumes less coal than existing plants An ultra-supercritical coal-fired plant consumes less coal than existing plants to create the same amount of electricity, addressing the “less coal” half of the equation. By using less coal, the plant emits less carbon dioxide per kilowatt generated. That helps address the greenhouse gas half of the equation until carbon capture and storage systems are commercially available. Ultra-supercritical receives less attention than IGCC because, on the surface, it isn’t radically different from today’s generation. The plant pulverizes coal to fuel burners that turn water to steam that drives a turbine to create electricity. But below the surface, significant advancements make ultra-supercritical much more efficient than previous pulverized-coal technologies. The earliest coal-fired generation, characterized as sub-critical, burned coal to bring water to a boil and used the steam to create electricity. AEP changed that in 1957 when the world’s first supercritical unit — Philo Unit 6 in Ohio — began operation. Philo produced higher pressure and higher temperatures, 90 E n E rgyB i z http://www.energycentral.com
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.