Compressed natural gas gains momentum

  • 09-Oct-2012 02:17 EDT
CNG Tractor1.JPG

This Freightliner M2-112 tractor is powered by an 8.9-L Cummins ISL-G natural gas engine. The onboard storage for CNG is located in the cabinet to the rear of the cab.

Compressed natural gas (CNG) is getting lots of attention from the engineers developing new technologies for delivering and storing the natural gas, but others are also heavily immersed in advancing CNG-related innovations.

“Since 2009, we’ve been developing a deep knowledge base as its relates to natural gas usage, and we’ve been sharing our experiences with suppliers and OEMs,” said Scott Perry, Vice President of Supply Management for Ryder’s Fleet Management Solutions group.

Perry, who made the comment during 3M’s Transportation Summit at its Livonia, MI, facility on Oct. 2, noted that Ryder has one of the country’s largest CNG fleets. By the end of 2012, Ryder will have more than 300 commercial Class 5-8 vehicles using the alternative fuel.

Ryder’s experiences with CNG include dealing with an unwanted consequence of the fast-fill fueling process.

“The pressure transfer of fuel from the storage device through the compressor into the storage tanks onboard the vehicle creates heat. That heat in and of itself builds pressure within the tanks, and it essentially prevents a complete fill of the storage vessel by unnaturally exacerbating the temperature,” Perry explained to SAE Magazines.

Increasing the diameter of fuel delivery lines, designing the plumbing layout with gradual curves rather than 90° elbows, as well as other modifications helped to reduce the restrictive points that drive up the temperature. While those changes addressed certain issues, “there is still a significant area of opportunity from an efficiency standpoint,” according to Perry.

Recent CNG technology programs include the development of new onboard vehicle storage vessels. Chesapeake Energy and 3M announced in early 2012 a collaboration to design, manufacture, and market a range of CNG tanks. The first product, expected in January 2013, will be a new type 4 composite over-wrapped tank that uses nanoparticle-enhanced resin and other proprietary 3M materials. (See for more on this collaboration.)

Matt Hilton, Key Account Manager for 3M Advanced Composites, told SAE Magazines, “3M’s first tank to market will be a 21.5-in x 60-in tank, which is targeted at light-duty commercial fleet vehicles. Additional tanks will be launched in the spring of 2013 for medium- and heavy-duty vehicles.”

The CNG tanks that 3M has produced and refined for internal development purposes during the past three years will translate into production application geometries that, depending on the size, will be up to 20% lighter, will have 5-20% greater capacity, as well as being less costly on a per liter basis than conventional type 4 tanks.

According to Venchurs Vehicle Systems CEO Jeff Wyatt, a CNG tank represents “almost 40% of the material cost of all components needed for a CNG vehicle conversion.” Venchurs, a CNG vehicle conversion firm based in Adrian, MI, is a Ford QVM (Qualified Vehicle Modifier) for F-250 and F-350 Super Duty trucks with gaseous prep 6.2-L engines.

On the cost scale, CNG’s public retail price is considerably cheaper than gasoline or diesel fuel. Norman Herrera, Director of Market Development for Chesapeake Energy, noted that Oklahoma’s recent average CNG price at its 63 public CNG fueling stations was approximately $1.50 per gasoline gallon equivalent. There are more than 1100 CNG stations in the U.S., compared to the approximate 160,000 retail fueling stations selling gasoline across the country.

Ujjwal Kumar, General Manager–North American Products for GE Oil & Gas Turbomachinery, said, “We want to change the way America fuels one box at a time,” referring to the company’s CNG In A Box solution. The plug-and-play unit features GE’s patented bearing design in the compressor, which “allows peak gas output over a wide range of inlet temperature and pressure conditions,” according to Kumar.

Available in the marketplace since the spring of 2012, the turnkey fueling system uses several GE technologies, including a high-speed reciprocating compressor and a motor/starter. The standard configuration includes a Wayne fuel dispenser that provides 3600 psi (248 bar) of fill pressure on each side.

“We went from concept to being production-ready in less than one year,” said Kumar, who added that GE has more than 250 units on order. “Right now, we are delivering one unit every week,” he said.

Navistar will launch new commercial trucks in early 2013 that will be CNG-compatible, including the International LoadStar. The low cab forward truck is designed for the waste/refuse industry.

According to Scott Sutarik, Sales and Marketing Manager for Alternative Fuels at Navistar, “The LoadStar will be released as a natural gas option before it’s available as a diesel option. Right now, the market for refuse vehicles is about 25% natural gas.”

The CNG engine is a Cummins Westport ISL-G, while the diesel-powered versions are a 10-L, 11-L, and 13-L MaxxForce engine.

Navistar’s upcoming TranStar, a regional haul tractor, will launch in a 4x2 configuration and a 6x4 configuration. “We’ll offer both configurations in CNG with 75 diesel gallon equivalent,” said Sutarik.

Offering CNG-fueled trucks meets today’s market needs. Said Sutarik, “We see a growing demand for natural-gas powered vehicles moving forward.”

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