Jim Collins

From the transport authority to the operator, the next speaker was Jim Collins, Fleet Manager for Go-Ahead. He said the company operates 4,500 buses a day, with an increasing focus on running in dense urban areas. He mentioned that the company is very aware of its social responsibility in the communities and environments it serves. One factor of this is ensuring its fleet reduces the amount of harmful emissions it gives off. Its efforts in doing this include making 5% of its fleet hybrids. It has also introduced 13 gas buses in Norfolk, being the first operator to fuel vehicles from mainstream gas stations. Jim said, ‘Our focus remains on reducing the amount of fuel we use and reducing the emissions of the fuel we use.’

Go-Ahead began working with Eminox in 2003, when it specified CRT equipment to meet the London LEZ emission standards. In 2011, the company introduced an SCRT programme to meet the demands of the Oxford Low Emission Zone, which comes into effect in January 2014. In London, it has 270 of its vehicles fitted with SCRT thanks mainly to the funding made available for this. However, 20 of these were funded by the operator as part of its own strategy.

Commenting on fitting this equipment, Jim said there was no impact on mpg, nor were there any maintenance issues or increased down time caused by them. When these systems were first installed, there were a number of initial maintenance issues, but these were soon resolved by Eminox. He describes the operator’s relationship with the company as strong.

In total, 294 of Go-Ahead’s Euro3 buses have been retrofitted with SCRTs. With financial help from the Clean Bus Technology Fund, 50 vehicles in Brighton Buses fleet are also to be fitted with SCRTs. One thing Jim said concerning the Euro standards was they give a false sense of certainty. Just because they have been proven to achieve a high level of emission reduction does not mean they will do in real life operation.

John Newington

John Newington from Maidstone Borough Council highlighted the work that the Kent and Medway Air Quality Partnership is doing to improve the environment. The network was set up in 1992 to monitor pollutants, results from which it would use to promote and improve air quality. It found that a lot of the issues are transport based. One of its findings was that places closer to the road network register more PM and NOx.

To give some perspective on the effects of poor air, John said that health issues caused by it cost twice as much as those brought about by physical inactivity (£10.7bn). He said poor air quality is comparable with the impact on health of alcohol abuse, which is estimated at £12-18bn per annum. Asthma, which costs the country £2.3bn a year, is exacerbated by poor air quality. In Dover, 4.92% of mortalities could be attributed to long term exposure to current levels of PM, whilst in Gravesham the figure is 5.92%. He said the impact on the population is ‘broad’.

So, what can be done? Transport is one key area to focus on, John claimed. However, he said ‘one size does not fit all’. He cited figures in Maidstone that found on the Wheatsheaf junction, the car accounted for 24% of Nitrogen based pollutants, whilst buses created 22%; however in the High Street, buses accounted for 93% of it.

John quoted figures from another study, where it was found that bus NO2 emissions for Euro1 to 4 were largely similar, but drop significantly at Euro5 (about 50% lower). The average coach and HGV NOx emissions were stable across all standards. He asked the question of whether looking at bus and coach is the only option, claiming vans have one of the highest NO2 and NOx emissions. ‘Should we be looking at SMEs to see if we can reduce any of their vans’ emissions? What are the barriers to this? Maybe we should be looking at these sort of things as well,’ he said.

Steve Rawson

Head of Retrofit Engineering at Eminox, Steve Rawson, spoke about the SCRT system in more depth. It is a combination of SCR (Selective Catalytic Reduction) and CRT (Continually Regenerative Trap). This combined system not only reduces PM and CO2, but NOx too. The CRT part of the system is ‘passive’, meaning it is sized for the vehicle but has no active control over how it runs in different conditions. This is where the SCR differs, which is an ‘active’ operation. It takes inputs from the engine and measures NOx in the exhaust gas, whilst its electronic control unit (ECU) uses algorithms to calculate the optimum temperature for the best operation of the system. An area the manufacturer has paid a lot of attention to with this device is in its urea injection system, which required a lot of engineering to ensure a good, homogeneous mix is achieved in the mixing section. It uses a ‘highly active’ Johnson Matthey catalyst to achieve optimum results. Independent tests at Millbrook have proved it reduced NOx by 88% and NO2 by 50%. Despite it only fairly recently being fitted in London, it has ‘actually been out there for some time’. So far, Eminox’s SCRT emission reduction technology has been fitted to over 600 buses.

Eminox has now secured 592 low NO2 buses for five operators, which are contracted for supply in 2013-14. For London, the system has been fitted on Dennis Darts and Volvo B7TL double deckers. On the latter vehicles, the close coupled system had to be relocated to the engine compartment, instead of beneath the passengers.

After his presentation, Steve went outside with attendees of the roadshow to demonstrate the SCRT unit on one of Go-Ahead’s Wrightbus bodied Volvo B7TLs currently used in London. Opening up the engine bay, he highlighted the fact the system is insulated to ensure the heat it generates for optimum operation is confined to the system itself, rather than throughout the engine bay.

Steve said Eminox has trained the FTA to do spot checks on the buses in London to ensure the SCRT systems are working properly. He also mentioned that TfL make inspections on vehicles to make sure the systems’ urea levels are correct. He does train some customers’ technicians up to service the devices, but claims most want to use Eminox’s repair and maintenance package.

Last word

Eminox’s Clean Bus Technology roadshow provided an interesting and eye opening insight into the effects of air quality and the role transport, in particular buses, can play to improve it. It was encouraging to see councils taking a proactive approach and the allocation of much needed funding to make it possible. It was a very informative workshop and well worth attending.

By Chris Peat