There's an interesting article on the front page of the business section in today's New York Times (available online here) about the use of palm oil to generate power in the Netherlands. Ostensibly, biofuels like palm oil are much preferred to fossil fuels because they are carbon neutral: Plants absorb carbon dioxide when alive and release the same amount when they're used for fuel.
But it now seems that the demand for palm oil in Europe became so high that the production of it in Indonesia prompted the clearing of rainforests and other activities that actually increased overall worldwide CO2 emissions. Because of their production of palm oil, Indonesia is now the world's third leading contributer to atmospheric carbon dioxide. (The U.S. and China rank first and second.)
It's a good lesson in the necessity of analyzing the entire chain of energy production rather than just the apparent benefits at the end.