Among the several clean coal technologies that DOE is developing there are as repowering technologies. The repowering technologies can be grouped into two categories. One is based on coal gasification as a means to convert coal into clean products to power gas turbines to generate electricity, and the other is based on coal combustion where coal is combusted to produce steam to power steam turbines to generate electricity. The concept of repowering is based on an idea where old and inefficient coal conversion technology is replaced with either of the above two types, while keeping most of the infrastructure in place. From an environmental standpoint, repowering concepts provide a future of sustained reduction in nationwide emissions of CO{sub 2}, SO{sub 2}, oxides of nitrogen, particulate matter, and solid waste. Currently, DOE has five coal gasification-based and five coal combustion-based projects in various stages of demonstration. Attempts are made in this paper to discuss some of the environmental attributes of these projects.