World Oil Outlook - Opec

88
a key question concerns the extent to which the captive road transport sector, may
also develop into a significant market for natural gas use.
Natural gas is already present in the road transportation sector, but only marginally.
Today, half of all natural gas vehicles registered globally can be found in three
countries: Pakistan, Iran and Argentina. This is due to a large advantage in pricing,
constraints in gasoline supply, and the availability of a substantial network of
natural gas fuel stations, for instance in Pakistan about 40% of cars are powered by
natural gas.
In the US, heavy, long-haul trucks in particular, have recently become the focus
for natural gas. Fuel contributes to about 37% of a truck’s total 13 operating costs
and from this perspective a switch to natural gas could become attractive for truck
owners, given the low natural gas price in the US compared to diesel. A few truck
operators have already switched to natural gas, but due to a lack of available public
natural gas stations they are maintaining their own private refuelling network.
Proposed US legislation suggests additional US$ tax incentives for the purchase of
new and the conversion of older trucks to natural gas. 14 Extra incentives may be
provided for enhancing the fuelling infrastructure in order to assure public availability
of natural gas.
Vehicles powered by natural gas have been around for some time; the technology
is mature and reliable, natural gas in the US is cheap and for new vehicles most
safety concerns have been resolved. In addition, the price premium to be paid for
new factory built natural gas cars has narrowed to about 10%, compared to diesel
powered sister models. Natural gas engines for road vehicles are built on conventional
four-stroke spark ignition architecture, similar to petrol engines, but with a
higher compression ratio. They can be operated by compressed natural gas (CNG)
or LNG, or petrol. Many CNG vehicles are equipped with an additional small tank
for gasoline: in case they run out of natural gas a seamless switch to petrol is possible,
enhancing range and flexibility. Although, in gasoline mode some sacrifices in
efficiencies and performance have to be accepted. In contrast to retrofits, new natural
gas vehicles with dedicated, turbocharged engines offer competitive efficiencies
and driving performance. Fewer emissions, and reduced oil change intervals add to
the basket of benefits.
Unfortunately, the energy density of retail CNG compares to only 20% of conventional
liquid fuels. This effectively requires tanks five times larger than needed
for traditional fuels. Consumers, especially commercial operators do not appreciate
such bulky tanks because it increases weight, and reduces the effective payload
and cargo space. LNG offers a ‘half way’ out of this dilemma, by freezing the gas