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Berkeley Scientists Find Better Way to Store NatGas For Transportation

University of California, Berkeley chemists who think a "metal-organic framework" (MOF) may be a method to simplify and increase the range of natural gas vehicles (NGV) published their findings online recently in advance of a report appearing in the journal Nature.

MOF, a porous and flexible material developed by a team led by chemistry professor Jeffrey Long, may allow compressed natural gas (CNG) fueling system manufacturers to pack more methane into tanks at lower pressures and temperatures, allowing for longer driving ranges and less hassle at the pump.

Long and his fellow researchers said MOFs undergo "a dramatic structural change" when they adsorb methane, rapidly changing from a nonporous to a highly porous material. MOF collapses when methane is extracted to run an NGV engine, for example.

One potential advantage is that MOF can be loaded with methane at relatively low (500-900 psi) pressures compared to typical CNG vehicles, which operate at 3,600 psi. In this regard, the Berkeley research tracks a pre-commercial product for NGV fueling being touted by Fremont, CA-based Cenergy Solutions.

A state-approved test of a vehicle was launched by Cenergy earlier this year, and other tests are coming (see Daily GPIApril 17). Cenergy hopes to be marketing the fueling system to fleets and consumer markets by the end of the year.

As with Cenergy's technology, the MOFs developed by the Berkeley researchers have a lot of internal surface area to adsorb gases -- "that is, for gas molecules to stick to the internal surfaces of the pores" -- and store them at high density. According to Long, that makes MOFs "one of the most promising materials" for adsorbed natural gas storage.

“This is a big advance, both in terms of capacity and thermal management,” Long said. “With these new flexible MOFs, you can get to capacities beyond what was thought possible with rigid MOFs.”

Elsewhere, a safety recall is underway for some 3,000 8.9-liter Cummins Westport ISL G NGV engines related to a turbocharger oil supply line, the National Highway Traffic Safety Administration (NHTSA) said. The concern is potential engine fires from possible oil leaks, according to NHTSA.

The affected engines were sold for use exclusively in Mack Trucks and Navistar vehicles, both as original equipment and as replacement equipment. The recall applies exclusively to Mack Trucks.

"If the turbocharger oil supply line oil leaks in the proximity of the engine exhaust manifold, there would be an increased risk of a fire," NHTSA said in its Oct. 20 recall notice. "Cummins will notify owners, and dealers will inspect for oil supply line interference or damage, eliminating the interference and replacing the oil supply line, as necessary, free of charge."

The federal agency said the recall is expected to begin Nov. 20. Owners may contact Cummins at (800) 343-7357. Cummins' number for the recall is C1673.

Separately, 50 Mack trucks are involved in a project by NGV Texas to be converted to operate on a dual-fuel CNG/diesel basis for Florida's Saddle Creek Transportation. The project will allow 70% diesel fuel displacement in the trucks' operations.

NGV Texas President Fury Zaidi called the project the first of its kind involving CNG. "Both NGV Texas and Saddle Creek are totally committed to the success of this project," Zaidi told Fleets & Fuels newsletter.

On the merger/acquisition front, Vancouver, BC-based Westport Innovations said it has satisfied the U.S. Hart-Scott-Rodino regulatory requirements to move ahead with its acquisition of Fuel Systems Solutions Inc. There is no other antitrust clearance required for the combination of the two NGV equipment manufacturers. Fuel Systems will be a wholly owned subsidiary of Westport.

Boston-based Xpress Natural Gas, a growing supplier of CNG to industrial customers in the Northeast, is expanding westerly and southerly. Xpress has its sights set on taking its "virtual pipeline" to Washington state and the company said it is also headed to Virginia (see Daily GPISept. 8). Xpress recently gained approval from the Port of Grays Harbor for a lease at Satsop Business Park in Elma, WA, for the site of its $3 million CNG supply facility. Separately, it is planning a $7.8 million CNG facility at Appomattox Center for Business and Commerce near Lynchburg, VA.

Meanwhile, CNG continues to expand into the heavy duty vehicle fleet markets with the Massachusetts Bay Transport Authority ordering 175 New Flyer Xcelsior XN40 CNG buses, and another 150 diesel-electric hybrid buses. In New York City, Manhattan Beer Distributors announced the acquisition of 35 CNG Volvo VNM 200 model tractor trucks to bring its fleet to 110 NGVs among a 500-vehicle fleet.

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