A multi-state propane supplier is poised to introduce a dual-fuel system for Class 8 diesels that promises significant savings with a relatively modest investment in equipment and a payback in under two years.

Blossman Services, North Carolina, is waiting on final governmental approval for a “blended fuel” system that injects varying amounts of propane autogas to replace diesel fuel in heavy duty truck engines. The system has been certified by the federal Environmental Protection Agency for a 14-liter Detroit Diesel Series 60, said Jessie Johnson, vice president of marketing.

The engine has been running for six months in a road tractor hauling auto parts between Pennsylvania and upstate New York, he said. In Canada there already are 150 to 200 trucks running with the system because EPA certification is not needed there, Johnson said.

Next to be certified is Volvo’s D13, which several interested fleets are running, he said. Mack’s MP8 version of the 12.8-liter diesel is also likely to be certified.

The system is certified for retrofitting onto existing diesels with at least 185,000 miles, which EPA calls intermediate useful life under its maintenance requirements, said Brent Kiomall, Blossman’s applications engineer. All emissions equipment must be retained, but later testing might show that some could be modified or removed.

Certification for new engines might follow with cooperation from truck and engine builders, Johnson said. Blossman expects to begin selling the first retrofit systems in October. 

The system is from Prins, a Dutch company, obtained through BL Energie of Canada, Blossman’s partner in this venture, Johnson said.

Blossman Services is a subsidiary of Blossman Gas, with corporate headquarters in Ocean Springs, Miss., which sells propane and gas accessories in five southern and mid-Atlantic states. It has its own fleet of service and delivery trucks, some running on propane, others on diesel, and some on other makers’ propane fumigation systems.

A Blossman-BL Energie blended-fuel system injects no propane at idle or full load to protect the diesel from overheating, Kionall said. In other conditions the system displaces up to 40% of the diesel fuel, depending on speed and load as read from existing engine sensors. The engine reverts to all diesel fuel if propane runs out or its controls get certain critical fault codes.

Electronic controls meter propane into the intake manifold, unlike fumigation systems that introduce propane at the turbocharger in addition to diesel, and can achieve only 20 to 25% use. 

Cost for a Blossman-BL Energie system is “in the $15,000 range,” about half the cost of a natural gas dual-fuel conversion, Johnson said, “because our system is based on spark ignition technology and uses some of the same parts. And the tanks are significantly less expensive. Our tanks typically run $1,000 to $1,200 apiece vs. $10,000 for a natural gas tank.”

A truck whose diesel tank holds 100 usable gallons would carry 30 usable gallons of propane, he said. Propane is measured in gasoline-equivalent gallons.

Propane is stored in a saddle tank at 150 to 200 psi, and the system’s working pressure is 312 psi, the national standard for on-road autogas systems, he explained. Compressed natural gas stores at 3,600 psi liquefied NG is kept at super-cold temperatures, which is why those tanks are so expensive.

“We’re aiming for terminal-to-terminal operations, where we could set up a fueling station for the fleet,” Johnson said. A propane autogas station with a tank, pump-dispenser, and electronic metering and data recording would cost about $50,000, but less for a manual pump. That’s a small fraction of the cost of a compressed or liquefied NG station.

“We’re shooting for a system that’s reasonably priced with a reasonable payback using an American product – 98% of propane is produced in America,” Johnson said. “But there are operations where natural gas makes sense, such as for companies with landfills where they’re extracting methane gas. That’s free product.”

Propane autogas prices vary, but usually are comparable to those for compressed natural gas, or half to one-third less than for diesel fuel, according to other sources. Payback for a Blossman-BL Energie propane conversion would be 12 to 14 months for a tractor running 120,000 to 140,000 miles a year, Johnson estimated, and of course longer for lower-mileage operations.

“We expect a certificate of conformity from the EPA for the Detroit engine in the next couple of weeks,” he said, “then we’re ready to go to market.”