The Joint Center for Artificial Photosynthesis was established at Caltech and its partner institutions in 2010 with one main goal: to find a cost-effective way to produce fuels using only sunlight, water and carbon dioxide. The natural process of photosynthesis in plants accomplishes exactly the same thing. As a result, such a solar fuel generation system is generally described as an artificial leaf.
The so-called hydrogen economy is an idea that has been kicking around for quite a while. The notion is to use hydrogen as a primary energy carrier – a fuel, if you will – that will both power our cars and store the energy generated by renewable sources like solar power and wind farms. The hydrogen would then be transported if necessary to where it is needed and used to provide energy when it is needed.