Robert Williams is a senior research scientist, emeritus, for the Andlinger Center for Energy and the Environment at Princeton University. His wide-ranging energy systems research has included energy end-use efficiency, industrial cogeneration, renewable energy (especially biomass, wind, photovoltaic), nuclear energy, synthetic fuels and systems, carbon dioxide capture and storage, energy in developing countries, and energy policy. An adviser to agencies, businesses and governments worldwide, Williams was one of 30 climate scientists and energy experts who co-authored a study on early actions for carbon mitigation. He is a fellow of the American Physical Society.