The obstacles to greater market penetration by natural gas in transportation are well known. CNG and LNG (liquefied natural gas) require new infrastructure. Many more retail gas facilities would be needed to assure motorists of convenient access at service stations. CNG takes a separate dispenser and compressor, while LNG requires both a new pump and insulated storage. Where pipeline gas is unavailable, such as in parts of the northeast, additional investments in the local "gas grid" may also be necessary.
Vehicle conversion costs represent another significant barrier. Engine modifications and crash-resistant fuel tanks add significant costs for both new vehicles and retrofits. Even with gas priced well below gasoline or diesel fuel, the payback for these costs can be lengthy. That's one reason that gas has made greater strides in bus, truck and delivery fleets in the US than for personal cars, since the more intensive use of such vehicles substantially shortens the resulting payout periods. Countries with high gas-vehicle penetration typically have government policies and incentives in place to promote the use of gas by mitigating these obstacles.
Italy leads the EU in CNG vehicle adoption, with more than 11% of new passenger cars equipped for natural gas last year. That compares to 0.01% for the US in 2012, where only one CNG model, a Honda, was sold. The Italian government promotes natural gas use in vehicles both directly and indirectly. The country provides a subsidy of €700 ($945) to purchasers of CNG automobiles, while manufacturers like Fiat offer discounts to expand their market for CNG cars. Incentives were even larger a few years ago. The government also makes retail petroleum products extraordinarily expensive with high taxes. So even though Italy is a large net importer of natural gas, CNG is much cheaper than gasoline or diesel at the pump.
Fuel availability may also have something to do with the disparity in adoption rates. Despite having an 83% smaller overall vehicle population , Italy has over 40% more CNG or "Autogas" refueling stations than the entire US, at around 900. This is due in part to state-level incentives, with 50-70% of the cost of a new CNG filling station reimbursed by regions such as Liguria, Lombardy, and Piemonte.
In terms of market penetration, Pakistan, which is self-sufficient in gas, leads the world in natural gas vehicles, at 80%. That translates into over 2 million CNG vehicles, the result of a determined effort on the part of the government to reduce imports of petroleum by shifting to domestic fuels, with gas as its best option. This is a common theme in the non-oil-exporting developing world, where oil imports impose a large drag on national trade balances. CNG use in Iran is even higher than in Pakistan, as an unintended consequence of protracted international sanctions.
For the US, where oil production is increasing and oil imports declining, a shift to natural gas for transportation is likely to remain an opportunity, rather than a matter of necessity. The "NATGAS Act", a bill proposing incentives for CNG and LNG along the lines of the Italian model has languished in the US Congress for several years. It remains to be seen whether this will become a higher priority in the newly elected Congress, which has shown early signs of interest in breaking the recent logjam on energy legislation.
In the meantime, adoption of natural gas vehicles in the US will proceed based on market forces, supported by a small advantage in the way CNG cars are counted in manufacturers' fleets under the stringent federal fuel economy regulations issued last summer. That could lead to natural gas fueling 3% of US vehicles --mostly trucks--by 2020, based on the analysis of a partner at McKinsey & Co. Much like the case for energy efficiency investments, the available savings indicate a much larger potential, but funds for CNG/LNG transport must compete with other priorities.