Hydrogen is an appealing energy source because: (1) it can be used in fuel cells (which have higher theoretical energy-conversion efficiency than traditional combustion devices); and (2) it produces no carbon dioxide emissions. Because hydrogen is an important industrial chemical, a limited production and distribution network already exists. To become a primary energy carrier, hydrogen must be produced safely and efficiently at scale using renewable energy feedstocks, not fossil fuels. For more information on specific research on hydrogen technology, click below.