When Bison Transport's big rigs pull into the Shell Flying J truck stop north of Calgary these days, some of them refuel not at the regular diesel pumps but at a liquefied natural-gas terminal.
The LNG station – the first of its kind in Canada – opened in March with Winnipeg-based Bison Transport Inc. as its main customer. The station is one of a growing number of initiatives across North America that could herald a new era for natural gas as a motor-vehicle fuel, especially for trucks and buses.
Across the country, the City of Hamilton is nearing a decision to buy a new fleet of compressed natural gas (CNG) buses.
Hamilton Street Railway, the city's public transit system, will present a report to city council within the next few months setting out the case for CNG-powered buses, says Mike Kirkopoulos, a city spokesman. If the council approves, an order is likely to be placed next year.
Gas has two advantages that have recently revived efforts to promote it as a rival to gasoline and diesel.
One is a glut in supply as the technology known as hydraulic fracturing, or fracking, unlocks vast shale rock deposits across a wide swath of the United States and Canada. Natural-gas prices have tumbled since the mid-2000s and are expected to remain stable for years, if not decades, to come.
Mike Omotoso, senior manager of global powertrain at LMC Automotive, a Michigan-based consultancy, estimates that in the United States natural gas costs $1-$2 a gallon less than gasoline, depending on the location and time of year.
Concern about climate change has also given gas a competitive edge. While it produces less energy than the equivalent amount of gasoline, it burns more cleanly, thus putting less carbon dioxide and other greenhouse gases into the air. Hamilton switched part of its bus fleet to CNG in the 1980s, but lacklustre vehicle performance and lack of funding to upgrade from early-generation engine technology, among other challenges, gradually eroded CNG's competitiveness.
"The cost to operate a CNG-powered vehicle then became significantly more expensive than a diesel-powered bus," Mr. Kirkopoulos said.
The pendulum is now swinging in the opposite direction, as tightening exhaust emission standards for diesel engines have pushed up maintenance costs for the city's diesel buses.
The latest campaign to promote LNG and CNG as alternatives to gasoline and diesel has so far centred on commercial vehicles. A brief spurt of interest in natural gas as a fuel for cars – especially taxis – during the 1980s and 1990s petered out as motorists chafed at the paucity of refuelling stations and the cost of converting to natural gas.
"We've certainly learned the hard way," says Alicia Milner, president of the Canadian Natural Gas Vehicle Alliance. "We've got to be a lot more strategic and focus on the niches where natural gas really does well."
The only factory-built car on the market now that is powered entirely by natural gas is a version of the Honda Civic. Only about 2,000 a year are sold in North America. Mr. Omotoso forecasts little, if any, increase for the foreseeable future.
One problem is that natural gas has been pushed out of the limelight by electric cars. "Building an infrastructure of natural-gas pumps across the country would be a large undertaking, and both the federal government and state governments have really pushed electric vehicles," Mr. Omotoso says.
Even so, the gas lobby is not giving up on light vehicles. Two U.S. groups, America's Natural Gas Alliance and the American Gas Association, rolled out six dual-fuel demonstration cars in June, proclaiming natural gas as the "abundant, clean and American" fuel.
Kathryn Clay, executive director of the Drive Natural Gas Initiative, a joint venture between ANGA and the AGA, said at the unveiling: "We believe consumers deserve more choices in the vehicles they drive and the fuel they use to power their vehicles."
The six vehicles – a BMW X3, Chrysler 300, Ford Mustang GT, GMC Acadia, Honda CRV and Hyundai Sonata – were bought from dealerships as regular gasoline-only models, and then converted to run on natural gas as well.
While the market for commercial vehicles shows more promise, it is still in its infancy. About 50 gas-powered models are on the market and Ms. Milner estimates that just under 10,000 vehicles are now on the road in Canada.
"For the average consumer doing 10-12,000 miles a year and with no infrastructure, [natural gas] doesn't make sense," Mr. Omotoso says. "But if you have 50 or 100 or more trucks and if those trucks do a lot of miles, it makes sense."
The list of commercial-vehicle customers is gradually growing. Vedder Transport Group of Abbotsford, B.C., and Quebec-based Groupe Robert Inc. are among others that have joined Bison by adding natural-gas fuelled rigs to their fleets. Garbage haulers seeking to burnish their "green" image are among the biggest customers. A school board in B.C.'s central Okanagan Valley has converted about a dozen buses to natural gas.
Even so, the numbers remain modest. Bison's fleet of 15 tractor-trailers, used between Calgary and Edmonton, amounts to only one-fifth of the number used on that route and a fraction of the company's 1,250-unit fleet.
Both Shell and Bison acknowledge that the new Calgary refuelling station is an experiment. "We're creating a new market, we recognize that takes time," says David Williams, a Shell Canada spokesman.
Trevor Fridfinnson, Bison's senior vice-president, says the project has so far had mixed results. On one hand, the company has realized some savings compared with diesel. But those savings have yet to reach the level Bison expected. One of the challenges has been to keep the liquefied gas at the required temperature of minus 160 degrees. "LNG needs to be more actively managed than a traditional fuel like diesel," Mr. Fridfinnson adds.
He sees the growth of the natural-gas fuel market as a gradual evolution, rather than a revolution. "It's going to be a small percentage for the foreseeable future," he says. "As to what happens in the longer term, you're going to need a crystal ball."