It's a phrase that is commonly used to describe a stubborn reluctance to seriously explore alternatives. There are many arguments, mostly economic, as to why this should be, but mostly it's due to the fact that there is too much money being made from oil.
One of the ironies of the recent oil spill was in watching the president of a Lousiana Parrish talking about how Obama's moratorium on deep water drilling would decimate the local economy. This said in the same breath with how the Obama Administration would help those fisherman whose livelihoods have been compromised.