Among the most enduring challenges for scientists and engineers interested in catalysis is the development of clean energy conversion processes. Much of the research reported in the first 100 volumes of Catalysis Today has been devoted to this subject; e.g., synthesis of clean fuels, catalytic combustion, natural gas utilization, and control of emissions from stationary and mobile sources, for example. There is a clear relationship between energy use and our standard of living, creating an ever increasing demand for affordable energy. At the same lime, environmental considerations require that this energy be generated and used with minimal impact on our surroundings. There are essentially three approaches to the use of fossil fuels to meet this challenge: (1) Lower emission technologies: more usable Btu/lb emission; (2) Higher efficiency: more usable Btu/Btu fuel; (3) "Renewable" energy: usable Btu without consuming nonrenewable fossil fuel. Catalysis can and will play a central role in each of these approaches. (c) 2004 Elsevier B.V. All rights reserved.