There is a lot said about "peak oil," that is, the imminent exhaustion of oil in the world. But, there are trillions of barrels of heavy oil in the ground. The problem is to get that oil out of the ground economically. The environmentalists oppose any attempts to produce the heavy oil. They want a sudden end to the use of fossil fuel rather than a more or less graceful transition over the next century or so. Here is an article about an in situ technique for converting the heavy oil to a lighter grade and extracting it for a rteasonable price. It appears that this price may be low enough to keep the various green technologies from being able to compete economically with fossil fuels in the forseeable future. Here is the article:

http://nextbigfuture.com/2008/09/petrobanks-capri-thai-processes-for.html