Natural gas and diesel dual-fuel engines: Do the numbers add up?

Updated Jan 8, 2014
The engine used in CCJ’s test drive was a 1996 model Detroit Diesel Series 60 engine that retrofitted with a natural gas system that allows the engine to burn both diesel and natural gas.The engine used in CCJ’s test drive was a 1996 model Detroit Diesel Series 60 engine that retrofitted with a natural gas system that allows the engine to burn both diesel and natural gas.

Note: This is Part 2 of a two-part series on dual-fuel engines, which are glider kit trucks powered with a diesel engine that has been refurbished and equipped with an APG/WheelTime retrofit natural gas system. Click here to see Part 1 about the test drive and more about the equipment.

Do the numbers add up?

I was impressed enough with the dual-fuel glider concept to ask a couple of AGP customers to talk about their experiences at the CCJ Fall Symposium last November in Scottsdale, AZ.

Part 1: Dual-Fuel test drive: A new way into the natural gas game?

First up was Brian Orr, president with Stewart Logistics, a FedEx Ground contractor out of Atlanta, GA. Orr said he was attracted to natural gas a couple of years ago due to its low price and his belief that he could use it to add $1 per gallon burned by his fleet to his bottom line.

Looking at acquisition costs, Orr calculated he could buy a new, diesel tractor for his runs for approximately $128,000. A similarly spec’d new natural gas tractor would cost between $180,000 and $200,000. But a retrofitted glider kit could be had for $110,000. Based on those calculations, Orr opted to try a glider kit built by Fitzgerald and took ownership of his first vehicle in October of 2013.

Video log: Fueling, driving natural gas glider kit

Today, Orr is running Series 60-powered dual-fuel two glider kits five days per week on a dedicated route between Atlanta and Meridian, MS. The trucks burn the diesel gallon equivalent (DGE) of 71 gallons a day. Orr typically buys the fuel for about 96 cents a gallon cheaper than diesel.

The result, he says, has been a 65 percent displacement of diesel fuel burned for cost savings of $68.16 a day per truck. “This works out to $340.80 in fuel cost savings a week,” Orr notes. “Or a total of $17,721.60 in yearly fuel cost savings per truck.”

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Mike Pope is president and CEO of Pope Transport, out of Racine, WI. Pope is a disarming, mid-Western farmer’s son who has a passion for data and hard numbers. Both he and Orr were pleasantly surprised upon comparing notes in Scottsdale to discover that the numbers both fleets were seeing were essentially identical. Pope differs slightly from Orr in that he initially opted to retrofit his existing (older) diesel trucks with the dual fuel natural gas system. Although he says he will be purchasing new glider kits with the system in the future.

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Pope’s first run with a natural gas retrofit truck in July 2013 – with himself behind the wheel – was from Sturtevant, WI to Gary, IN. Using a conventional diesel truck, Pope expected to see an average of 5.62 miles per gallon on that 210 mile trip. But, with an initial 50 percent displacement of diesel fuel used, that average (for diesel only) jumped to 12.35 miles per gallon. Pope calculated that his total fuel cost per mile – for both natural gas and diesel – was 54 cents a gallon: a savings of 17 cents per mile over his diesel trucks.

The Freightliner Cascadia driven in CCJ’s drive test.The Freightliner Cascadia driven in CCJ’s drive test.

Today, Pope has expanded his fleet of dual fuel gliders and completed no less than 16 separate fuel tests with the trucks to get a handle on his costs and savings. His fleet today includes 8 dual fuel trucks; 2 trucks have 450 horsepower Mercedes-Benz MB 400 engines. Six trucks are running 500 horsepower Detroit Series 60 engines. All told, Pope says, he’s invested $210,000 in retrofitting his trucks with payback coming in 14 to 16 months at fuel savings between 10 and 20 cents per mile.

Looking ahead, Pope says he fully expects to overhaul and convert his remaining trucks to the dual fuel natural gas system between 700,000 and 900,000 miles. His long-term, projected fleet savings numbers once the entire fleet is converted (based on his current fuel test numbers) indicate fuel cost savings for 25 trucks running 50,000 miles a week $10,000 per week or $500,000 per year. And those numbers don’t factor in other potential cost savings, Pope adds. As a farmer, he already has a natural gas line running to his farm to dry his corn harvest. By adding his own fueling equipment for his trucks, Pope calculates he can further extend his fuel cost savings as much as $822,500 per year.

For both Orr and Pope, the natural gas numbers are adding up nicely in the real world. “I got into this business to make money,” Orr says. “For the life of me, I don’t understand why everyone isn’t trying this. Because the numbers work.”

It’s a sentiment Pope agrees with. “Today, we once again have the opportunity to control our costs and make a profit,” he says. “For me, trucking just got fun again!”