<http://schema.org/about>
"The concept of the \"hydrogen economy\" was quite popular until people started to ask where all that hydrogen would come from. One possible path is using bacteria, another is solar energy: Penn State researchers have announced a proof-of-concept device"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/renewable-energy/water-photolysis-turning-the-suns-light-directly-into-hydrogen.html>