Will Plummeting Oil Prices Cause a Clean-Energy Meltdown?

Both John McCain and Barack Obama say America needs renewable energy—wind, solar, nuclear and "clean coal" as opposed to oil and natural gas. When the price of oil was rising, those alternative technologies were attracting needed investment. But oil now costs half what it did just a few weeks ago. Added to that, the credit crisis is drying up capital and green-energy projects that looked promising are being put on hold. What about energy independence and global warming? Does government have the resources to take up the slack? Are renewables really the answer to the world's energy problems?