With coal-fired electricity from the Rockies states waiting in the wings for Californians, even in a coal-friendly state such as Wyoming, environmental restrictions may limit just how much coal generation is built. However, state officials remain unclear on how much federal pollution limitations may curb development. The apparent limits on coal-fired generation stem from federal and state clean-air rules that restrict how many pollutants can be released into the atmosphere and degrade the quality of so-called Class 1 areas. Jim Martin, executive director of Western Resource Advocates, based in Boulder, Colorado, said the 1992 amendments to the Clean Air Act created three classes of air quality. Most of the country falls into Class 2 areas, where air quality and visibility are about average. Class 1 areas, however, are considered pristine. Where air quality in most parts of the country has to be at or slightly above ?ambient? quality, Class 1 areas can tolerate little if any degradation in quality. That can limit the extent of industrial uses upwind of Class 1 areas, in the so-called airshed zones. Class 1 areas generally are found in national parks and in many national forests across the West. The National Park Service raised concerns about a coal plant near Gillette, Wyoming?Black Hills Energy?s 500 MW Wygen No. 2?and its potential effect on visibility downwind at the Class 1 Wind Cave National Park and Badlands National Park in South Dakota. Wyoming air-quality officials approved the plant, but the National Park Service appealed the decision. That appeal is still pending, according to a spokesperson. ?In Wyoming, Montana, Utah, New Mexico, Arizona, and Colorado, it?s hard to build a plant that would not violate? clean-air standards, Martin said. In Wyoming in particular, officials with the state Department of Environmental Quality (DEQ) are beginning to worry about bumping into emissions ceilings. As a result, it may be difficult to obtain permits to build coal-fired power plants in places that are upwind of Class 1 areas. Late last month, for example, Black Hills decided to scale back the size of Wygen No. 2, set for development near its Wyodak coal mine in northeastern Wyoming. Originally permitted to build a 500 MW plant, the Rapid City, South Dakota?based company now says it may build no more than 100 MW. Initial plans called for the Wygen No. 2 station to export some of that power to California. But developers cited the lack of available transmission lines and unfavorable market conditions, rather than pollution concerns, as leading it to shelve 400 MW for now. The 100 MW it plans to build will serve local load growth. The company did not return phone calls seeking comment. Just how much new coal-fired generation can be built in Wyoming remains to be seen. John Corra, director of the DEQ, disputed local news reports suggesting that 500 MW would consume available airshed tolerance in northeastern Wyoming. ?I don?t think 500 MW is the limit,? he said. Corra said he did not believe it would be productive for his agency to ?go through a big exercise? to determine how much capacity could be added before upper limits were reached. ?There?s some ceiling, but nobody knows what it is just yet.? Colorado-based Two Elk Generation Partners reportedly has an emissions permit in hand for a 310 MW coal-fired plant in the area. And Basin Electric Cooperative has said it plans to build 250 MW in the region, perhaps even considering integrated gasification combined-cycle (IGCC) technology, which would lower emissions considerably. Corra said the 500 MW Wygen No. 2 station was the cleanest coal-fired plant his agency had ever permitted. The Powder River Basin, source of an enormous amount of low-sulfur coal that is burned in dozens of power plants as far east as Georgia, has ?an accumulating set of air-quality issues,? Martin said. Corra said the Powder River Basin has a ?significant amount? of environmental monitoring equipment in place given the area?s coal mining and natural gas production. <b>Sempra?s New Idaho Coal Plant Not Meant for CA<\/b> Sempra Generation selected a site in Jerome County, Idaho, for a $1 billion, 600 MW power plant that would market electricity to the Pacific Northwest, Idaho, and Nevada?but not to California. The company is going before the county?s planning and zoning commission later this month to ask for permission to build a meteorological tower on the site, where it will gather weather information and air-quality data prior to holding community meetings. The company could begin filing for permits next year, said Art Larson, a company spokesperson. Sempra Generation favored the site in part because groundwater is nearby for thermal cooling. The site is also within several miles of an electrical substation, offering transmission access. Larson said the plant would burn low-sulfur coal from the Powder River Basin in Montana and Wyoming and could buy additional coal from mines in Utah. Larson said that would help make the plant ?88 percent cleaner? than coal plants built 20 years ago. If the company secures the necessary permits, work on the plant could begin in late 2007 and could create 1,000 construction jobs. The generating station could enter service in 2011 or 2012. A number of environmental groups appear ready to oppose the plant.