Not scalable for passenger cars at the number driven today.
Before you count out CNG..India started a program to convert all their buses and cabs to CNG. The infrastructure is mostly there. You install gas compressors at gas stations to compress natural gas into cylinders to fill the vehicles. We already have the gas pipelines. The tanks are bigger, which is not much of problem for commercial vehicles and taxis..and if the carmakers go on it they could solve the design issue of where to put the tanks in passenger cars.
We should eliminate the use of natural gas for epg and convert all that to nuclear while shifting natural gas to heating and vehicles. We have lots of natural gas in NA..with more reserves every day.
One of my Auto Gnomes told me what the added price is for off the assembly line, but that is not for here. Yes it is more. But down in AU their gasoline this summer was $4.80 American and their Gaseous fuel was 80 cents a gallon. Suplant Direct Injectors with Gaseous Direct Injectors, for even higher compression ratios or more turbo-boost for downsized engines with a nice kick.
All we need is Congress and Obongo to get off their @$$ and make it a reality.
As someone who has been reseaching this fuel for cars for over 2 years, Sarah Palin was right when she said Natural Gas is the fuel of the future...
Not without trading oil imports for natural gas imports.
Or a vast drilling program after the ejection of many politicians.
It would take a couple decades, and would be better as a split between oil and gas.
For trucks why not use steam? The only failing is you have to build up a head of steam and that takes 20 minutes. BUT Long Haul Truckers would not have a problem with this and the savings would be dramatic. There is that exploding thing and scalding to death thing (Listen to the Wreck of the old 97).