LPG Guides Buses to Cleaner Environment

Increasing concern over the levels of environmental pollution in urban areas, coupled with the government's continuing commitment to above-inflation rises in the price of petrol and diesel, has led to considerable growth in demand for engines converted to run on LPG (liquefied petroleum gas). There are millions of LPG-powered cars and LCVs currently operating throughout the world, and the UK's leading supplier of LPG, calor is one of a number of pioneering companies which are helping to ensure that the environmental and financial benefits associated with LPG powered engines are being experienced by many more drivers in the UK. Thanks to ongoing developments in engine technology, conversions can be carried out on petrol engined cars and LCVs, and on diesel engines in buses, coaches and other vehicles.

The environmental benefits of LPG engines are particularly beneficial to operators of diesel engined commercial vehicles such as buses taxis, which cover high mileage and release a large proportion of particulate-laden emission directly into the town and inner city areas which they service. One company reaping the benefits of having its buses powered by Calor Autogas in five UK locations is Guide Friday, the largest operator of sightseeing tours in key heritage towns and cities where environmental issues have high priority.

Guide Friday carries in excess of a million visitors every year on its distinctive green and cream, open top double decker buses in 38 town and cities. In the early 1990s, Guide Friday recognised growing concerns of both the public and government about high levels of emission from diesel fleets of buses and HGVs in particular, and began to assess the practicalities of moving to a cleaner form of fuel.

Guide Friday's engineering director David Lampitt explained: "Our concern for a cleaner environment in town and city centres prompted us to evaluate other fuel options, and led us to LPG as the most practical and economical alternative to diesel. Working closely with Calor, we researched and developed a relatively straightforward conversion process for our diesel engines which can be carried out at a fraction of the cost of replacing the entire engine.

"We have converted nearly 30 of our buses running on daily scheduled services in Stratford Upon Avon, Edinburgh, Dublin, Lincoln and York. These buses are around 70% cleaner and 30% quieter than those running on diesel, and the fuel is much cheaper. We are accredited and approved by the LPG Association as conversion specialists and plan to continue the programme of conversions to increase the number of Autogas powered buses on our fleets."

Most heavy duty diesel engines are suitable for conversion. Although converting a diesel engine to run off LPG requires more modification than for a petrol engine, the benefits are even more significant. When a diesel engine is converted to run on LPG, nitrogen dioxide emissions are reduced by 80% and particulates by 90%, whilst carbon monoxide emissions are reduced to levels well below those specified by the Health & Safety Executive.

The environmental benefits of LPG powered vehicles have been recognised by the government which, by increasing excise duty on petrol and diesel whilst holding it stable on LPG, has encouraged the use of LPG by making other fuels around 50% more expensive in comparison. The cost benefits of running vehicles on LPG encourage bus operators like Guide Friday, and companies running vehicle fleets, to take advantage of convenient centralised refuelling facilities on site, linked to bulk storage tanks of Calor Autogas.

In addition, the cleaner-burning qualities of LPG help to extend engine life and mean that Guide Friday's Autogas powered buses require less maintenance, keeping servicing costs down. In some cases, diesel engine conversions can also entitle the fleet operator to a reduced pollution certificate, which in turn lowers road tax by £330 per annum on every converted vehicle.

David Lampitt continued: "The Calor powered buses have been a success all round. As well as the obvious environmental and cost benefits, drivers have commented on the buses being easier to drive, because the converted engines are smoother and more responsive, and our engineers find the LPG engines easier and quicker to service. Of course, our passengers probably benefit the most - the buses are quieter, there is less vibration resulting in a smoother ride and there are no sooty, diesel exhaust fumes being emitted.

"The success of the conversions to date has encouraged us to offer our conversion expertise to other bus companies, undertaking conversion and supporting operators with training on maintenance and repair. We are also working closely with calor, developing enhancements to the conversion process which will make converted diesel engines even cleaner. We are about to introduce a much modified engine conversion which is up to Euro 3 specification, which includes Lambda fuel control and a tree-way catalyst."