A Technology Review article from 2002.
Known reserves of natural gas, which is composed mainly of the simple hydrocarbon methane, will last for about 50 years at today's consumption rate. Estimates of likely but as yet undiscovered gas resources extend that projection to about 200 years. But when the natural gas thought to lie buried deep under the ocean in methane hydrates is added in, the potential is mind-boggling. Hydrates, ice crystals that trap methane molecules, form below a depth of 300 meters as a result of methane-producing bacteria. Very little is known about how much gas is bottled up in these crystals or how to get it out, but best guesses are that the reserves could, even with natural-gas consumption rates doubling over the next several decades, last tens of thousands of years.
Using natural gas for transportation will drive up the cost of the conventional stuff. As usual, there are issues with methane clathrate, too... http://en.wikipedia....Methane_clathrate
Cheers,
Scott.
