<http://schema.org/about>
"Anti-renewable energy people often claim that it takes a lot of energy to make wind turbines so they aren't as clean as they seem. Let's look at the facts."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/renewable-energy/energy-paypack-2-megawatt-wind-turbine-lasts-over-20-years-5-8-months.html>