How’s this for the ultimate in renewable energy: a waste hauler drops a load of garbage at a landfill site, and then pulls around front and tanks up on locally produced biomethane gas. The garbage he just delivered will, in time, become the very same gas used to power the truck.

We’re sitting on gazillions of cubic feet of this man-made fuel, and we make more every time a load of trash is bulldozed into a landfill site.

Biomethane is part of a family of gaseous fuels already powering commercial vehicles in many parts of the world. There are more than 20,000 medium- and heavy-duty engines in service today burning a variety of natural gases, including biomethane.

Pricing tends to be more stable too, and that adds to the value proposition. "In 2008, for example, we saw a dollar-per-gallon spread between diesel and natural gas in the overall cost of operation calculation," says Tony Picarello, vice president of fuel systems at Westport Innovations.

A clean, sustainable fuel source that’s readily available from domestic feed stocks? Where do I sign? Despite burgeoning interest in natural gas, either liquefied or compressed (LNG or CNG), there are several very real barriers to its widespread acceptance as a commercial vehicle fuel. Cost is one, but clean-air credits and tax incentives are making a difference on that front. Fuel distribution and storage infrastructure is another. You won’t find many natural gas fuel stops and liquid natural gas dispensaries are even rarer.

A diesel-equivalent LNG fuel tank requires a 119-gal capacity to cover the same ground as 65 gal of diesel.

"One gallon of diesel contains the energy equivalent of 1.7 gallons of natural gas, so more fuel is required to cover the same distance," Picarello points out. "However, once the equivalency calculations are applied, the fuel economy results between natural gas and diesel are nearly identical."

Historically, natural gas engines have been converted gasoline engines that weren’t quite up to the challenge of medium- and heavy-duty commercial applications. They offered neither the power output nor the robustness of a diesel, until the early 1980s when Professor Philip Hill of the University of British Columbia’s (UBC) Mechanical Engineering Department began working with natural gas combustion in diesel engines.

The CWI ISL-G will run on a variety of
natural gas feed stocks, including common
natural gas, propane, and biomethane

That technology led to the creation of Vancouver, B.C.’s Westport Innovations in 1994.

In 1999, Westport and Cummins Inc. began development of HPDI technology for use on the Cummins ISX engine. And then in 2001 Westport and Cummins formed a joint venture called Cummins Westport to enhance and expand Cummins‘ spark-ignited natural gas engines and related technologies to on-highway vehicles, as well as industrial and power generation applications.

Today, two separate and distinct natural gas engines bearing the Westport fingerprint are in service around the world. The 15-liter, 450-hp/1,750-lb-ft Westport Innovations ISX HPDI heavy-duty engine, and the ISL-G engine from Cummins Westport Inc. The latter is a medium-duty, spark-ignited, 8.9-liter, pure natural gas engine built on the Cummins ISL platform.

Medium or Heavy Duty?

The ISX HPDI engine has been in revenue service since 2001. San Francisco-based waste hauler, Nor-Cal Waste Systems was an early adopter, and now has several units with more than 750,000 miles on them and a fleet total of more than six million miles. Refinements have been made to the engine since we drove one in late 2005 (see “Future Fuels,” Today’s Trucking, May 2006).

Several hundred engines are in service today in North America, though Paccar  is currently the only truck maker offering this engine.

Kenworth began production of T800 models with ISX HPDI engines last January and has more than 150 in customer hands as of February ’09. Peterbilt  began offering the engines last fall in 367, 386, and 387 models following field trials with Wal-Mart in early 2008.

The heavy-duty ISX HPDI engines are capable of a 300-mile round-trip at 80,000 lb GVW with a typical single fuel tank installation, double that with two tanks, and of course, you still need a small tank for the diesel fuel used to ignite the natural gas.

This engine will require both a DPF and SCR aftertreatment system to meet EPA 2010. While emissions of EPA-regulated materials will be the same as any other diesel engine come 2010, natural gas engines offer the added benefit of a 33 percent reduction in GHG emissions.

Jeff Campbell, director of product marketing at CWI, says there’s an up-charge of about $50,000 (CDN) for the natural gas version of the ISL engine.

"I’d stress that because the engine is sold as part of the complete vehicle package; we talk about vehicle pricing, not just the cost of the engine," he says. "There are the modifications to the fuel system, obviously, as well as on-board storage, etc."

Incentives available in some American jurisdictions kick close to $30,000 back to the end user to offset the up-charge. The best we’ve seen in Canada to date is a $15,000 rebate made available through Ontario’s recently announced Green Commercial Vehicle Program (GCVP) 

More than a Science Project:

Being relatively new to market, natural gas engines are still “on probation” in many fleet eyes. Historically, natural gas engines have been there and then they weren’t. There has been concern about continued production, parts availability, etc. But if the recently introduced natural gas version of the Sterling Set-back 113 is any example, Daimler is making a pretty serious commitment to natural gas.

Brian Daniels, powertrain product manager at Daimler Trucks North America, says that while a lot of others have had a go at natural gas engines over the years, the Sterling/ISL-G combo is an example of the full engineering effort that’s required to get it right and make it stick.

"This isn’t a science project for us," he says. "There are low-level conversions and diesel retrofits available, but we hope to be successful by making this a full engineering effort, with all the design, testing, validation, and optimization required to maintain our quality and durability standards."

The chassis modifications required to accommodate the ISL-G engine are not extensive. Daniels says the engine is very similar to the diesel version in terms of size and packaging, and so did not demand a load of re-engineering.

"When we look at chassis modifications, the biggest thing we’re talking about is fuel tank placement," he says. "Other components we had to consider are the fuel line routing, placement of the heat exchanger, and the methane detection system."

By the way, with the recent demise of the Sterling brand, DTNA says work is underway to integrate the CWI ISL-G engine into the M2 Business Class chassis. It will be available this year.

Daniels echoed Campbell’s remarks on pricing. "Our target is $50,000 incremental over a diesel, but there are incentives in many areas to offset that, and we have some expertise in helping our customers gain access to some of that funding,” Daniels notes. “And we see fuel pricing being a big factor in the buying decision–when diesel prices begin to climb again, natural gas will look pretty good."

THE FIRING LINE: Individual ignition coils are
located directly above each spark plug,
eliminating the need for high-tension leads.

As well, Daniels says many service tenders are going out now with "cleanest available technology" in the bid language. All things being equal, even EPA 2010 engines will be at a 19-percent disadvantage in terms of CO2 emissions.

So far, municipalities have been the largest consumers of these engines, with equipment running now in transit, refuse, construction, and utility applications. Private sector uptake has been limited to applications that come with buying incentives, but there’s fertile ground there for OEs with the technology in hand.

And how about Canada? Glad you asked. According to Brian Zehr, vice president of the customer care group at Westport Innovations in Vancouver, there are no commercial units operating in Canada.

"Challenger Motor Freight  tested a few engines for us back in 2005-2006, and came away with a positive impression, but it needs a larger scale operation to get a more permanent and cost-effective fueling infrastructure in place," he notes. "We probably won‘t see that until we get some large-scale incentive programs in place."

There are many natural gas transit buses in service, and decent demand from cities and municipalities for natural gas powered vehicles, but there has been little uptake so far from the private sector.

Ontario’s Green Commercial Vehicle Program could pump as much as $15,000 into the purchase of a natural gas vehicle — a far cry from the $28,800 available through the Clean Truck Super Fund — but it’s better than a poke in the eye. An organization called the Western Climate Initiative, a coalition of seven U.S. states and four Canadian provinces, is looking at the big picture on climate change, and may eventually come to the table with some funding, but there’s nothing there at the moment.

The existing engines are selling well in Australia and other markets around the world, and last July Westport signed a development agreement with an undisclosed “leading European diesel engine maker” to integrate HPDI technology with that platform. But try as you might, you won’t find but a handful of medium- or heavy-duty natural gas engines, if any, on Canadian roads. Ironic, isn’t it, that cutting-edge Canadian technology is making the rest of the world a better place to live, but we can’t get it here?