I agree with AP, fossil fuel is definitely going to be replaced by other alternatives in long run. However, future projections of petroleum production are always not true. Several people just use the total proven reserve in the world today and divide that number by the production rate. I don't konw why they overlook petroleum resources which are yet to convert into reserves. Many believe that we are in peak oil and petroleum will last only for 25-30 more years.

THE OIL RESERVE FALLACY
Proven reserves are not a measure of future supply

To begin with, one of the most revealing speeches about world oil reserves went unremarked in 2006. The head of the world's largest oil company, Saudi Aramco, said:

“We are looking at more than four and a half trillion barrels of potentially recoverable oil. That number translates into 140 years of oil at current rates of consumption, or to put it anther way, the world has only consumed about 18 percent of its conventional oil potential. That fact alone should discredit the argument that peak oil is imminent and put our minds at ease concerning future petrol supplies.”  

http://www.runet.edu/~wkovarik/oil/

US is certianly not in favor of hydro-electricity rather it can switch to natural gas as Washington is looking for cleaner energy. China, however, seems to be interested in developing more hydropower. Considered as the cleanest energy for long time hydroelectricity has also gained some environmental criticism. Some of these seem merely hypothetical, however, some have real impacts.

Hydropower Doesn't Count as Clean Energy

http://www.alternet.org/environment/64445/