Philip Verleger has some interesting things to say on why we had a spike in oil prices last year and when it could possibly happen again.
Philip Verleger, February 19,2009 at UCSD 59min 25sec
While it is an hour long presentation I strongly suggest watching it if you are interested in the energy markets.
The gist of his talk is how environmental regulation changes regarding low sulpher diesel excacerbated energy prices in 2008. The upcoming cleaner requirements for low sulpher shipping fuel may possibly create a simliar situation by 2020.