Driven by a combination of low-cost natural gas and sustained higher prices for gasoline and diesel, the market for NGVs is gaining traction in many regions. While these vehicles have been in service in certain countries for many decades, interest in NGVs has spread recently along with the surge in supply of low-cost natural gas.
"NGVs experienced a brief surge in popularity in the 1970s and early 1980s as a result of the 1973 oil embargo and the price shocks that followed," said Dave Hurst, principal research analyst with Navigant Research. "Today, growth in the market is being fueled less by negative external events and more by positive industry developments, such as increased vehicle availability, a stronger focus on the largest users of fuel in new regions, and a greater openness to alternative fuel vehicles on the part of motorists and fleet operators."
The number of NGVs on the road worldwide will increase steadily over the remainder of the decade, reaching 34.9 million by 2020, up from 18.2 million in 2013, according to Navigant Research.
Natural gas, which exists as a gas at ambient air temperature, must be compressed (CNG) or liquefied (LNG) in order to increase the volume of fuel the vehicle can carry and to improve the vehicle's range. CNG is compressed to 3,600 pounds per square inch. LNG occupies about 30 percent less space than CNG, but the gas must be super-cooled to -259°F (-160°C) before it liquefies. While more LNG fuel fits into the same amount of space as CNG, LNG tanks are larger, heavier, and more costly, limiting LNG to medium- and heavy-duty trucks and buses, according to Navigant.