About ten miles north of where I live in northern Colorado, a smokestack rises 500 feet in the air alongside a stair-step series of buildings. On a summer day, nothing appears to be coming from the smokestack, as though it is a ghostly relic; in the winter, a white plume rises. On closer approach, a lake teeming with ducks, geese, pelicans, and other waterfowl sits in the foreground. A herd of American bison roam on over 4,000 acres of grasslands surrounding the smokestack. This apparently benign plant called Rawhide Energy Station is actually a 280 MWe coal-fired power plant that provides about one-quarter of the electricity for four nearby communities—Fort Collins, Loveland, Longmont, and Estes Park. It is a public utility owned by the four communities and is near state-of-the-art for a coal-fired power plant, being one of the most efficient in the western United States and among the top ten in lowest emissions. I drove up to the Rawhide Energy Station and called on an intercom box to the security station to identify myself so the guard could open the security gate for me to enter. After driving across the edge of the lake, the armed guard then directed me to the visitor center. I met Jon Little, the knowledgeable and friendly tour guide, and a group of bicyclists from a local environmentally conscious brewery who were taking the tour also. We put on headphones with a radio set and a hard hat for the tour. The first and largest building houses the boiler and the generators. Th e coal arrives by train in five- to six-inch lumps, which are broken down into one-inch lumps before being fed by conveyor to grinders that convert it into a powder finer than facial powder. This powder is then mixed with air and blown into the 16-story. boiler from four directions, where it burns efficiently at a hellish temperature of 2,800˚F.
Use of MCDM techniques in environmentally conscious manufacturing and product recovery: State of the art
