After seeing how Thailand has fully incorporated natural gas into their transportation system, It seems that the United States, with it's large natural gas resources could also easily switch a lot of our transportation system over to natural gas. This NY Times article is a good description of the current situation.
http://mobile.nytimes.com/2013/10/30/automobiles/natural-gas-waits-for-its-moment.html
http://mobile.nytimes.com/2013/10/30/automobiles/natural-gas-waits-for-its-moment.html
