MIT researchers have overcome a major barrier to store solar power for use when the sun doesn’t shine. The new process will allow the sun’s energy to be used to split water into hydrogen and oxygen gases. Later, the oxygen and hydrogen may be recombined inside a fuel cell, creating carbon-free electricity day or night. The developers, Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and Matthew Kanan, a postdoctoral fellow in Nocera’s laboratory are describing the work in the July 31 issue of Science. More engineering work needs to be done to integrate the new scientific discovery into existing photovoltaic systems, but Nocera hopes that within 10 years, for instance, homeowners will be able to power their homes in daylight through solar cells, while using excess solar energy to produce hydrogen and oxygen to power their own household fuel cell. James Barber, the Ernst Chain Professor of Biochemistry at Imperial College London, who was not involved in this research, called the discovery by Nocera and Kanan a “giant leap” toward generating carbon-free energy on a massive scale.