As the leading contributor of greenhouse gas emissions, the electricity sector stands to be impacted by policies seeking to curtail emissions. Instead of increasing electricity from renewable resources or nuclear power facilities, an alternative approach to reducing emissions in the electric power sector is changing the dispatch order of fossil fuels. Important differences between fossil fuels, and in the technologies used to burn them, make it possible to substantially reduce emissions from the sector. On average, each gigawatt-year of electricity generation switched from coal to natural gas reduces CO2 emissions by 59 percent. As a result of significant investments in natural gas fired power plants in the United States between 1998 and 2005, there is an opportunity for electricity producers to take advantage of underutilized capacity. This is the first study to closely examine the new capital additions and analyze the technical potential for reductions in emissions. The analysis finds that 188 GW of capacity May be available to replace coal-fired baseload electricity generation. Utilizing this excess gas-fired capacity will reduce the sector's CO2 emissions by 23 to 42 percent and reduce overall U.S. CO2 emissions between 9 percent and 17 percent. (C) 2012 Elsevier Ltd. All rights reserved.