Daniel Nocera, a scientist at MIT, led a project group that successfully developed the first practical leaf. You won't notice it when you see it, as it is an advanced solar cell with the size of a poker card that mimics photosynthesis - the process that converts sunlight and water to energy.
According to Nocera, the device would require about a gallon of water and exposure to bright sunlight to supply a household in a developing country with one day of electricity. The energy is created by splitting water into hydrogen and oxygen. The hydrogen and oxygen gases would be stored in a fuel cell, which would be used as a power source.
"A practical artificial leaf has been one of the Holy Grails of science for decades," said Nocera. "We believe we have done it. The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station," he said. "One can envision villages in India and Africa not long from now purchasing an affordable basic power system based on this technology."