Air quality: bus emissions
Together, RATP’s 4,500 buses account for less than 5% of air pollution in Île-de-France. This result is a reflection of long-term company policy.
The majority of RATP’s bus fleet runs on diesel. The gradual renewal of the fleet will allow existing buses to be replaced with models that are compatible with the Euro V standards, in accordance with the European regulation that has been in force since autumn 2009. Today, the RATP fleet is still, for the most part, made up of buses compatible with Euro II or Euro III. A standard bus is kept for 15 years, while an articulated bus remains in service for 10 years.
Annual local emissions of regulated pollutants from buses (CO, HC, NOx and particles) are compared to an internal database concerning emissions from the various buses in the fleet.
RATP is taking action on a
number of fronts to reduce the pollution generated by its fleet:
- RATP systematically purchases the least polluting buses as soon as they become available. By doing so, it has been able to anticipate the entry into force of European standards, most recently Euro V;
- Since 2004, RATP has purchased its buses on the basis of their whole life cost: energy costs over the life span of the bus are taken into account when awarding contracts;
- In 2009, RATP purchased its buses in accordance with the EU Clean Vehicles Directive, which will be transposed into French law at the end of 2010.
Since 1997, RATP has experimented with various fuels: diesel, natural gas, Liquefied Petroleum Gas (LPG), B30 (a mixture of 30% vegetable oil-based biodiesel and diesel), Aquazole (a mixture of 10% water and 90% diesel) and electricity. These experiments have allowed it to gauge the reliability of each technology.
Today, RATP is particularly interested in hybrid technology (the pairing of an internal combustion engine with an electric or hydraulic motor). In 2011, it will introduce hybrid buses into its fleet, after their performance levels have been tested.
In the longer term, RATP is interested in second-generation biofuels.
The most polluting buses are systematically equipped with emission control systems (particulate filters). These reduce emissions of particles, carbon monoxide and unburnt hydrocarbons.
An annual competition called the “Eco-challenge” rewards the bus lines and maintenance centres that achieve the biggest reductions in fuel consumption. The Eco-challenge represents an opportunity for teams to improve air quality and save energy.