Reuters: Investors in clean energy are like motorists stuck at broken traffic lights. The public policy light is green, but the price and credit lights are deep red. Investment in wind, wave and solar power should be booming after the European Union adopted an ambitious goal last year to draw 20 percent of its energy from renewable sources by 2020 to help fight global warming, and President Barack Obama made green power a central plank of his government’s policy. But the credit crunch, …