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Lacking ready access to oil deposits, Swedish commercial vehicle maker Vo vo has been
Page 56
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looking for home-grown alternative fuels.
Brian Weatherley reports on one possibility.
Not having a handy gusher in your own backyard helps to focus the mind on alternative fuels. And with no natural fossil fuels to rely on, it is hardly surprising that the two Swedish commercial vehicle giants have been developing trucks and buses powered by a fuel derived from one thing that Sweden has plenty of... wood pulp.
While Scania has been engaged in a long-running city bus programme based around ethanol as a fuel,Volvo has been concentrating its efforts on a truck project using DME — dimethyl ether (see panel).
Volvo's first foray into DME-fuelled vehicles was in the late 1990s when it built a prototype bus to demonstrate its capabilities and low-emission advantages. But the field tests were not concluded due to problems with the original fuelling system.
Undeterred, the Swedish manufacturer launched its second-generation DME vehicle — its first DME-powered truck — last year, based around an FM rigid with the fuelling system of the truck's conventional 9.4-litre six-cylinder engine modified to run on DME.
The DME-fuelled D9 engine's injection pressure is less than 20% of that of an equivalent diesel engine.The engine also has what Volvo describes as along route' exhaust gas recirculation (EGR), which is something of a novelty considering its commitment to Selective Catalytic Reduction (SCR) for its Euro-4 and Euro-5 diesel engines. Nevertheless, Volvo insists: "This is possible because the exhaust gases have close to zero PM [particulate matter, or soot], and emissions from the engine are lower than Euro-5 standards."
Clean-burning and efficient
While a truck engine needs to be 'tuned' to run on DME,Volvo reports: "Even prior to optimising the engine and support systems, fuel consumption is,in energy equivalents, almost the same as a diesel engine." Following the launch of the original DME prototype rigid last year. Volvo will have three more DME-fuelled test trucks running by the end of this year.
On the face of it. DME offers a number of