London Bu' i run on gas?
Page 23
If you've noticed an error in this article please click here to report it so we can fix it.
• A prototype bus, powered by compressed natural gas (CNG), could be operating with London Buses before the end of 1988 — if the Department of Trade and Industry unlocks a £100,000 development grant in the new year.
The CNG bus would initially be fitted with a conventional diesel engine converted to run on a mixture of CNG and derv, with the quantity of CNG used in the combustion process controlled by an on-board microprocessor unit.
A more advanced version, however, could be run entirely on CNG using an existing diesel engine, but extensively modified to run as a spark ignition power unit.
Driving force behind the project is Blackburn-based Enercol Energy Systems. Following approaches to London Buses it has been trying to set up a pilot scheme involving the conversion of a conventional diesel-engined bus and the setting up of a natural gas fuelling point at an LB garage.
Through its part-owners Lancashire Enterprises, (a new business creation division of Lancashire County Council), Enercol is asking for a £100,000 development grant from the DTI to proceed with its plans. The department is expected to make its decision on whether to back the scheme some time in January.
London Buses' vehicle engineering manager Colin Curtis says that LB would be interested to take part in CNG trials and provide test vehicles, but stresses that any financing must come from outside.
Should the DTI give the scheme the go-ahead, and provide a grant, Curtis expects the CNG bus project to operate on two stages, with an initial dual-fuel (CNG/Diesel) conversion being carried out on a 90kW (120hp) Routemaster.
The single-decker has already been used by LB as a test bed for liquified petroleum gas (LPG) operations.
If these tests prove successful, says Curtis the next step would be to convert one of LB's Gardner-engined MCW Metrobus or Leyland Titan, double-deckers. The evaluation vehicles, however, are unlikely to run on regular services.
Curtis says that LB is committed to looking at alternative fuels and six years ago carried out its own project into the feasibility of using LPGpowered buses.
While the project would be the first attempt by Enercol to convert a large diesel-engined commercial vehicle, a number of its conversions are being used by Blackburn Council on CDVs and light commercials.
Enercol's John Harwood says that before an engine can be run on CNG its characteristics must be carefully determined by a process called 'mapping', where performance data is programmed into an on-board micro-processor which controls the amount of CNG used. On a dual-fuel vehicle the CNG is stored as a gas at pressures of up to 200bar (3,000psi), and fed into the inlet manifold of the engine. Diesel is injected directly into the cylinder as normal.
On full engine load, such as when pulling away from a stop, the diesel/CNG ratio is roughly 60:40, but on motorway operations it can change to 20:80. Combustion in the dual-fuel engine is ensured by the presence of diesel fuel, although a CNG-only engine, based on a conventional diesel power unit, would require extensive modification, including the removal of the fuel injection system, the fitting of a gas carburettor and revised cylinder heads.
Enercol's John Harwood claims the CNG engine is not only cleaner and cheaper to run than a diesel unit, but it also suffers none of the marked valve seat recession experienced with many LPG engine conversions.
0 Trials with the Volvo Cumulo bus are now at an end. LB says the energy-recycling vehicle has been returned to the manufacturer and that there are no plans "at the moment" to take the project any further.