I have looked at Matt Simmons theory of "Peak Oil", and can see that it has a lot of merit. There have been several books written on this subject, both for and against.
I personally do think that we have already reached 'peak oil', and that reserves will run out, and probably sooner than even Matt Simmons believed.
This is why I support wholeheartedly a change to renewable and sustainable energy sources. Matt Simmons was a pioneer of this idea and a promoter of research into renewable energy.