Commercial fleets have been slow to add natural gas vehicles to their fleets globally due to the significant upfront purchase cost and relatively high cost of conversion, according to a new research report.

The market for vehicles powered by compressed natural gas or liquified natural gas remains in its infancy, according to "Commercial Natural Gas Vehicle Market 2014-2024" by data provider Visiongain.

The 126-page report predicts that global sales of natural gas vehicles should reach 1.1 million in 2014. The market still represents high potential for growth in the coming decade, especially in the heavy-duty trucking segment, according to the report.

Other segments such as work trucks, vans, buses and motor coaches could also see significant growth.

For the full report, click here.