According to a new report from Navigant Research, worldwide sales of natural gas trucks and buses will grow from 170,200 annually in 2013 to 398,400 by 2022.

The report, “Natural Gas Trucks and Buses,” analyzes the global market for buses and trucks that are in the medium duty (10,000 to 26,000 pounds) and heavy duty (26,000 pounds or more) gross vehicle weight classes. The study provides an analysis of related market issues and drivers, including refueling availability, competing alternative drive technology, total cost of ownership, vehicle availability, and government influence. Global market forecasts for vehicle sales, vehicles on the ground, and fuel used are broken out by segment, fuel type, and region and extend through 2022.

The report also examines the key technologies related to natural gas storage on vehicles, as well as the competitive landscape.

Driven by the lower cost of natural gas and the lower emissions from natural gas engines, compared to diesel fuel, operators of truck and bus fleets are increasingly shifting to natural gas vehicles.

New markets for natural gas vehicles, such as the U.S. and China, tend to focus on fleet markets, particularly trucks and buses, because they require fewer refueling stations and fuel has become the highest or second highest cost for fleets.

“Demand for natural gas trucks and buses remains uneven on a regional basis,” said Dave Hurst, principal research analyst with Navigant Research. “In North America, where natural gas costs remain low, the number of vehicles is outstripping the development of refueling stations. In Asia Pacific, China and other developing markets are looking to natural gas to help address environmental woes in large cities. As a result, the total number of natural gas trucks and buses on the road by 2022 is anticipated to reach nearly 4 million.”

On average, the price of compressed natural gas (CNG) is about 42% that of diesel, according to the report. Liquefied natural gas (LNG) tends to be a bit higher, but sees significantly more variability than CNG. Given the difference, the payback period for heavy duty trucks can be as short as 1.5 years in North America. The incremental costs are largely driven by storage tanks for the CNG or LNG, which account for between 53% and 76% of the total incremental costs.