From IBD via CNN Money:
Keeping it clean recently has translated to keeping the profits rolling in for many investors.
Those who put their money behind "clean" energy companies, which focus on renewable resources, saw the happy results all week.
Several factors were behind the rise. Last week, President Bush signed the Energy Independence and Security Act of 2007 into law. The bill mandates lowered fossil fuel use and quadrupled alternative biofuel use over the next 15 years.
Exchange traded funds that track clean energy (NASDAQ:CLNE) began to rise immediately after the bill became law. The largest and oldest, PowerShares WilderHill Clean Energy
(including an amazing chart of one of the funds)