Kenworth leads way
There is a new approach with LNG, writesGRAHAMSMITH
US TRUCKMAKER Kenworth has taken the lead in the alternative-fuels race by releasing Australia’s first, and so far only, full-production liquefied natural gas truck.
But it has found LNG needs a rethink of the way it designs and builds trucks.
Having built more than 40,000 diesel trucks over almost 40 years, Kenworth has made an art of custom-building heavy-duty trucks to suit the needs of owners, but it’s finding it has to do things differently with LNG trucks.
There are limitations in designing an LNG truck and they can ultimately mean the truck can’t be perfectly tailored to the job. For the first time, Kenworth is telling customers they may have to fit the job to the truck if they want to switch to LNG.
It’s a major shift in philosophy for the company. LNG tanks add to the weight and take more chassis space than the diesel tanks they replace, which may have an adverse affect on the wheelbase of the truck, weight splits, turntable positioning and, ultimately, even the length of the trailers.
There is no doubt about LNG’s benefits: it costs less than diesel, is price stable because it’s sourced locally and not affected by currency fluctuations, supply is not affected by international politics and it reduces greenhouse gas emissions.
Downsides include the fact there isn’t a widespread network of refuelling stations, the system has a high upfront cost on top of what is already a premium-priced truck, and there’s the issue of who might want to buy it when it comes time to sell.
Kenworth won’t divulge the cost of its LNG truck, except to say it is substantial, but Big Wheels has previously learnt from Westport, the LNG system provider, that its system costs $150,000 or more depending on which gas capacity configuration is needed.
That’s not an issue for operators whose trucks are doing high mileages, but for those with trucks not running big distances it can be expensive.
One of the issues an operator needs to consider when contemplating a switch is the distance between refuelling stops.
Diesel-powered Kenworths can be fitted with tanks capable of taking 1500 litres, giving the truck a range of 2500km or so before you need to refuel a typical B-double. That will take them from Melbourne to Sydney and back, Sydney to Brisbane and return, or even Melbourne to Brisbane.
But the range of an equivalent Kenworth LNG truck is 850km depending on whether it is fitted with one, two or three tanks.
Kenworth is offering LNG on three models; the T908 bonneted truck as seen at the Brisbane truck show last month, the T408 SAR conventional model and the K108 cab-over.
The company is using the Westport HPDI system developed by the Canadian gaseous fuel systems specialist Westport Innovations.
The engine is based on the 15-litre Cummins ISX, but uses Westport’s electronic HPDI injectors, control systems and tanks.
The system is a dedicated LNG unit, not dual-fuel, which makes the refuelling issue a vital one. Run out of LNG on the Westport system and your truck is stranded.
A small amount of diesel is used to start the combustion process before the LNG is injected, and both fuels are ported into the cylinder through the same HPDI injector.
The LNG is stored under pressure at temperatures as low as -160C before being vaporised using heat from the engine’s cooling system and distributed to the injectors using a common fuel rail.
Kenworth offers power ratings of 373kW, 410kW and 433kW at 1800 revs, with peak torque of 2235Nm and 2505Nm at 1200 revs.
The peak figures not only match those of the Cummins ISX engine, but the torque curve is also a perfect match for the diesel engine.
Drivers who have tested the LNG motor say the trucks perform as well as an equivalent diesel, and do it more quietly.
In developing the LNG system, Kenworth used the experience it gained in the field trials run by Westport in Western Australia and Victoria from late 2007 to early last year.
Those tests were conducted on four Kenworth trucks, but the LNG systems were retrofitted.
Unlike the test models, Kenworth is now building LNG trucks on its assembly line, making it a more integrated installation.
It’s a small but important step, with interest in LNG from potential customers gathering momentum.
With the anticipated expansion of the refuelling network and the price stability LNG offers, along with the reduction in greenhouse gas from using it, Kenworth is confident the demand for the LNG trucks will grow.
Shift in philosophy: LNG tanks add to the weight and take up more chassis space than the diesel tanks they replace.