Summary: Coal provides about one quarter of the nation's energy needs, but emissions from coal combustion have contributed to air pollution, including acid rain. Under a program to provide more advanced, efficient, and environmentally acceptable coal utilization technologies, the Department of Energy (DOE) funds up to 50 percent of the costs of industry-sponsored projects to demonstrate commercial-scale applications of innovative clean coal technologies. As of September 1991, about half of the 32 ongoing funded projects were progressing on schedule and within cost estimates. Equipment failures, additional equipment requirements, and problems in scheduling tests were contributing factors to projects that were behind schedule or over budget. GAO believes that DOE's selection of some projects, while meeting selection criteria, may not be the most effective use of federal funds. For example, some projects are demonstrating technologies that might have been commercialized without federal assistance. GAO also identifies projects with potentially limited applications and projects that have proven economically unviable. GAO questions whether DOE has done all that it could to ensure that its investment is adequately protected. For example, DOE continued to fund some projects that it knew were experiencing financing problems and that were eventually withdrawn from the program; DOE has since improved controls over project costs.