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Rocky Mountain Institute
Managing Director
Business Strategy for Clean Energy


Stephen is a member of the senior leadership team at Rocky Mountain Institute (RMI) where he uses his expertise in energy efficiency, solar PV, electricity, buildings and industry operations to help catalyze business led transformations to sustainable energy systems. He is currently focused on three areas: Island economy energy transitions, Community scale solar, and Africa energy transitions. He also led the teams that supported the retrofit of the Empire Building that reduced energy us by 40% with a 3.5 year payback; developed and deployed an 5-nines data center that uses 80% less energy than industry average; provided the analytical underpinnings of “Reinventing Fire”, and that helped develop the comprehensive energy plan for the state of Connecticut.

Prior to RMI, Stephen was a senior leader at McKinsey & Co. where he focused on the Sustainability and Operations Practices. The sustainability work included a range of heavy industrial energy efficiency and energy productivity action plans including a 15% reduction of energy intensity at an integrated steel mill, and development of the design principles for a heavy industry process (iron ore pelletization) that will generate energy rather than consume it. His nine years of operations experience underpins the sustainability work and includes purchasing, lean manufacturing and product development across a diverse range of sector ranging from remote power generation, heavy industry and military and civilian aircraft to hospital operating theaters, automotive and insurance.

Stephen has also been a senior advisor to the U.S. Air Force where he helped develop a strategy to reduce infrastructure energy use by 30% in 10 years and increase the use of renewables to >20%. He has also worked directly with base commanders on specific energy productivity and efficiency opportunities including a far-flung outpost in the Aleutian Islands, Germany and across the continental U.S.

Stephen holds a BA in Chemistry from Dartmouth College, a Ph.D. in physical chemistry from U.C. Berkeley, and postdoctoral experience at the Mayo Clinic and the California Institute of Technology. He has taught operations at Wharton and chemistry at two U.S. colleges. He lives in a super-efficient, off-grid home in New Hampshire that he built with his wife, Marion Cass. It uses 1/10 th the electricity and 25% of the thermal energy of standard U.S. home.