<http://schema.org/about>
"While sticking electrodes into tree trunks to harvest energy probably won't power your fridge, car, or household lights anytime soon, a recent piece in New Scientist reminds us how the very small amounts of energy that can"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/renewable-energy/is-tapping-trees-the-greenest-electricity-source-out-there.html>