Robert H. Williams is a Senior Research Scientist at the Princeton Environmental Institute (PEI), Princeton University, where he heads the Energy Systems Analysis Group and the Carbon Capture Group.

While Assistant Professor of Physics at the University of Michigan, 1970-1972, he shifted his research from basic physics to energy systems analysis. In 1972 he became Chief Scientist with the Ford Foundation's Energy Policy Project. He has been at Princeton University since 1975. His energy systems research has included energy end-use efficiency, industrial cogeneration, renewable energy, nuclear energy, synthetic fuels in a carbon-constrained world, and fossil-renewable energy synergisms.

Williams got a B.S. from Yale University (1962) and a Ph.D. from the University of California, Berkeley (1967), both in physics.

Williams received the Leo Szilard Award for Physics in the Public Interest (American Physical Society, 1988), the Sadi Carnot Award for energy efficiency contributions (US Department of Energy, 1991), a MacArthur Prize (1993), and the Palladium Medal (National Audubon Society, 1995). Williams was also a co-recipient of the Volvo Environment Prize in 2000.

He is a Lead Author of the Fossil Energy Knowledge Module of the ongoing Global Energy Assessment. From 1993 to 2002 he served as an international member of the Working Group on Energy of the China Council for International Cooperation on Environment and Development.