About two years ago, Raven Transport started switching its over-the-road tractor fleet to operate on liquefied natural gas. It expects to be running 100% on LNG by 2019.

Stephen Silverman, chief operating officer of the Jacksonville, Fla.-based truckload carrier, explains the transition was driven by three factors: addressing customers’ sustainability goals, contributing to U.S. energy independence, and lowering fuel costs for the 500-truck fleet.

“When we began buying LNG trucks in 2013,” he says, “we made the decision to go to LNG on day cabs as our first step. Then when [our customer] P&G included us in their sustainability program if we committed to LNG, it became a no-brainer.”

He points out that LNG power dovetails with Raven’s willingness to tailor its operations to the needs of customers. “Environmental stewardship and cost-effective logistics are central to the operating principles of our customers, which is why our investment in a natural gas fleet makes sense.”

In putting together its LNG truck fleet, Raven’s executives met with Clean Energy Fuels founder T. Boone Pickens. Silverman says they were impressed by his argument for the need to reduce the nation’s dependence on foreign oil by making more use of domestic natural gas.

The carrier was also intrigued by the potential per-gallon cost savings from running on LNG versus diesel. However, Silverman agrees that it’s difficult to quantify the effect on overall fuel costs today because of significantly lower oil and diesel prices. He also points out that it’s still “too early to tell about the impact on maintenance costs, since most of our historical maintenance costs escalate in the third and fourth years.”

The first order in the fall of 2013 was for day cabs, and earlier this year the fleet began to bring on LNG-fired sleeper trucks. Its natural-gas fleet now consists of 115 sleepers and 69 day cabs with 20 more on order. The fleet consists of Peterbilts powered by the Cummins Westport 12-liter engine, but Raven is looking at other tractor vendors as well.

The LNG day cabs can handle a 54,500-pound payload and have a range of around 670 miles, while the sleeper payload is 48,400 pounds and the range extends to just under 1,100 miles.

“The day cabs were purchased for our business partner MillerCoors and the sleepers with our long-term business partner P&G in mind, but we provide service with these trucks to other customers as well.”

About 98% of Raven’s LNG fueling is done at “truck-friendly” stations opened across the Southeast and in Texas, through a multi-year agreement the fleet signed with Clean Energy Fuels.