Introducing clean public transport buses

Summary

As part of its efforts to create a cleaner public transport fleet, La Rochelle purchased 10 new buses that comply with European standards for enhanced environmentally friendly vehicles.

Implementing sustainable mobility

Enhanced environmentally friendly vehicle (EEV) is a term used in European emissions standards to define a vehicle that complies with the most stringent exhaust emissions standard. 

The objective of this measure was to improve the environmental performance of the bus fleet in La Rochelle by purchasing 10 new buses equipped for full compliance with EEV standards.

These buses use a process known as selective catalytic reduction (SCR) that injects an aqueous urea solution, marketed under the name of AdBlue, into the gas stream and converts 85 percent of the nitrogen oxides in the exhaust gases into nitrogen and steam.

Progress

An initial study was undertaken into the technical aspects of compliance with EEV norms, and contacts were made with European bus manufacturers for the purchase of the new EEV buses. The first five new buses were purchased in 2007 and successfully tested in real conditions. This was followed by the purchase of five more buses in 2008.

Outcomes

• Fuel consumption fell by 2.12 percent. Although EEV standard requires the addition of AdBlue, the fuel costs are similar to those of Euro 3 buses.
• Pollutant emissions fell dramatically compared to those from a Euro 3 engine: an analysis of exhaust gases showed a drop in emissions of carbon monoxide (by 98 percent), hydrocarbons (98 percent), nitrogen oxides (68 percent) and particulate matter (89 percent). These good results can be explained by the addition of the AdBlue solution and the installation of particulate filters.
• The new buses proved to be at least as reliable as the buses with Euro 3 engines.
• Overall, the new buses proved to be environmentally favourable and economically viable, demonstrating that mature diesel technology can achieve environmental goals and meet operational requirements. The adoption of EEV standards is a practical way for cities and transport operators to deal with the transition between older technologies and the radical change towards completely renewable energy sources.