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Study Details Methane Emissions in Heavy-Duty NGVs

A recent study by West Virginia University (WVU) researchers says tailpipe and engine crankcases are the most significant sources of pump-to-wheels (PTW) methane emissions in heavy-duty natural gas vehicles (NGV).

The study by the university's Center for Alternative Fuels, Engines and Emissions is the first project in the Environmental Defense Fund's (EDF) methane research series, which has 11 industry groups involved, including the American Gas Association (AGA), International Council on Clean Transportation, Cummins Westport, and various other energy companies and major fleet operators.

"The time to get ahead of this methane supply chain leakage problem is now," EDF said.

While tailpipes/crankcases account for roughly 30% and 39% of PTW emissions, respectively, fueling station methane emissions, according to the West Virginia study, were relatively low at about 12%. Researchers based the fueling station estimates on the assumption that liquefied natural gas (LNG) stations have sufficient sales volume to effectively manage boil off gases, or fuel lost as vapors, EDF said.

Trade group NGVAmerica President Matt Godlewski told NGI on Thursday that the study published by Environmental Science & Technology drew support from numerous gas industry players, including a number of his organization's members. Godlewski said the NGV industry is taking a "proactive approach to reducing methane emissions and the study provides a valuable baseline."

EDF and NGVAmerica appear to agree that the NGV sector -- using both LNG and compressed natural gas (CNG) -- needs to learn more about the amounts of methane emitted in the PTW chain. WVU's study said in its introduction that PTW methane emissions from the heavy-duty transportation sector "have climate change implications that are poorly documented."

EDF has  stressed that the study reaffirms that "adopting emission reduction technologies and practices to curb methane escaping during the production, transport and delivery of natural gas used in transportation is critical to unlock the full environmental potential of NGVs."

According to EDF, only 3% of the heavy-duty trucks in the United States run on natural gas, but the prospects are that market share could become as high as 50% during the next two decades as the industry and fleet operators focus on switching to LNG and CNG. The growth spurt assumes a return to relatively high oil and diesel prices.

In addition, the use of natural gas in utility vehicles and transit buses continues to grow, EDF said, with 11% of those vehicles now operating on natural gas.

Godlewski said the WVU findings "confirm that many of the technologies being deployed on the latest generation of NGV engines and refueling infrastructure are dramatically lowering emissions." Fueling infrastructure and stations contribute less than 20% of the methane emissions, according to the study, he said.

"NGVAmerica applauds the cooperative approach taken with this study and will incorporate its findings in the ongoing work of our technology/development committee that evaluates product enhancements and best practices," Godlewski said.

Separately, in Canada a second recent study already noted in the province of Ontario by governmental officials, has recommended that fleet operators "work closely with relevant government parties and industry stakeholders" early and often to ensure conversions are done correctly and in compliance with regulations the first time.

The study, "Natural Gas as an Alternative Fuel for Canadian Truck Fleets," said CNG fleet conversions are large projects "and as such, should be given the proper management and financial attention. Commissioned by the Ontario Trucking Association, the study concludes that CNG "has a strong future in Ontario, particularly with heavy-duty fleets.

Among the sections of the report is a summary of the differences between CNG and LNG as used in transportation, noting that while both are derived from natural gas, "they are handled and transported much differently, as well as exhibiting different energy characteristics."

In California, later in January, the California NGV Coalition is hosting a day long workshop, demonstration and ride/drive on the next generation of NGV trucks. It will focus on the new Cummins Westport 11.9-liter low nitrogen oxide engine. The program will be held at the Clean Energy Fuels Corp. station in the Port of Long Beach in Southern California.

Globally, LNG's immersion into the marine transportation sector continues in the new year with announcement of new LNG vessels in the Caribbean and Europe.

Korea-based Gas Entec has developed engineering services and a "total cargo handling equipment package" for a new barge that will be based in Jacksonville, FL, transporting LNG fuel to two container ships operating in the Caribbean. This project is for an LNG-fueled barge that was ordered by Clean Marine Energy two years ago.

In Europe, the maiden voyage of Gasum's Skangas' first LNG-powered high-speed ferry, Megastar, between Tallinn, Estonia and Helsinki, Finland, is to take place later this month. The 696-foot (212-meter) ferry is being completed at Finland's Meyer Turku Shipyard. The new ship will have a service speed of 27 knots.

Elsewhere, a signpost for the NGV sector can be found in San Diego where the city government has made the commitment to convert a fleet of 900 heavy- and medium-duty vehicles from diesel, but the new fuel won't be natural gas, it will be renewable diesel. And eventually, all of San Diego's municipal fleet of 1,125 diesel vehicles will be switched to renewable fuel.

The city of San Diego signed a deal with Soco Group for the initial phase of the conversion, including its fire department vehicles. City officials said the renewable diesel will cut greenhouse gas emissions nearly 80%.

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