Ken­worth leads way

There is a new ap­proach with LNG, writesGRAHAMSMITH

Herald Sun - Motoring - - Front Page -

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.

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