We all know that the fuel required for renewable sources of energy are virtually limitless, hence the name. But what about the essential components that renewables like wind turbines and solar panels rely on to function? An article from The Economist (subscription required) highlights several production problems for the "clean-tech boom":

THESE should be heady times for Vestas, a Danish firm that makes more than a quarter of the world's wind turbines. The wind business is booming, and the company said last week that it had swung into profit in 2006, thanks to an 8% rise in revenue. But there is “significant unexploited production capacity”, Vestas says, due to shortages of high-quality turbine components. Other companies grumble about a lack of gearboxes and bearings.