Going for gas
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Natural gas vehicles could supersede diesels in the 21st century: we assess an early example.
by Bill Brock • BOC Distribution Services has introduced a natural gas vehicle (NGV) into its Transhield fleet. It plans to replace all 1,250 diesel-poweredvehicles within seven years.
Over the next six months the 17-tonne ERF rigid, powered by a modified Perkins Phaser 210, will be used to assess the commercial viability of compressed natural gas (CNG). It replaces a diesel-powered truck making deliveries of chilled and ambient foods to Marks and Spencer stores in the South of England.
Chief engineer Sam de Beaux says: -"The environmental implications of running on natural gas are well known, and it is the equivalent of 50p per gallon cheaper than diesel. That would give us a saving of over £5m a year, but we would have to reinvest in a large on-site filling station. The sums for a fleet of our size look good but you need to use a lot of gas to make savings overall, so it might be unrealistic for a very small operation with just one or two trucks. If the 17-tonner proves the theory there is no reason that 300hp engines shouldn't be available for our 1,100 tractive units. Large cities will eventually ban vehicles which pollute the air and we have to be ready for it".
There are more than a million NGVs operating world wide. It is predicted that the USA will have four million NGVs by the year 2000; the UK expects to have some 200,000. BOC's experiment is a joint venture with British Gas, which has so far built eight refuelling sites with 20 more in the pipeline.
Perkins has 30 years' experience with CNG engines in the off-road sector: 250,000 are in service throughout Europe, Australia and the US. Tony Downes, Perkins' director of engineering concepts, says: "Natural gas is the only alternative to petrol and diesel that has a real chance of becoming a third forecourt fuel. From a safety point of view it is nontoxic, lighter than air and it has a high ignition temperature." The Phaser gas engine is expected to go into production within two years. The compression ratio has been reduced from 17.5:1 to 12.0:1, and ignition is by sparkplug, but air-toair charge-cooling and the wastegate turbocharger remain the same
NG Engine 2.00 0.02 0.80 0.20 as for diesel units. A lean-burn combustion system and an oxidation catalyst minimises emission pollutants. Power output is unchanged at 210hp; torque is up slightly to 5441bft. The price should be close to that of Euro-2 diesel units.The Lane Group also runs a CNG-powered ERF 17-tonner as part of the Body Shop's distribution fleet; in this case power is courtesy of a catalyst-equipped 240hp Cummins L10 (CM 26 May 1994).
The BOC ERFs fuel system includes eight 90-litre high-pressure gas containers, the equivalent of 50 gallons of derv. It was installed by British Gas at Warrington; pipework runs inside the chassis for protection. Payload is down by 900kg, but this is no problem to Transhield which usually bulks out long before reaching maximum weight.
Gas comes from the mains supply fed to a Sulzer refuelling unit at Transhield's Hemel Hempstead depot. It takes just over three hours to compress the gas to 250bar. It is stored in two dozen 68-litre cylinders: sufficient to refuel up to four vehicles a day. A dryer removes moisture to eliminate corrosion.
Cleaner fuel can have benefits
in terms of engine life and reduced maintenance costs but the proof is in everyday operation: CM went for a drive with Spud Murphy, who has been with the company for seven years. The truck is exceptionally quiet inside and out: we sMod beside it with the engine running—a truck on the other side of the yard sounded noisier.
Murphy says: "It pulls down the revs with a full load, no problem It's very responsive on the throttle. There is no delay whatsoever and it's very smooth. I'm driving in London every day and it's easy to keep up with the traffic. It goes well on the motorway as well."