Low emission buses in London

There are 2,535 hybrid buses, 71 electric buses, and eight hydrogen buses currently operating in London, out of a total bus fleet of 9,616. The first hybrid bus was introduced on route 360 in March 2006 and over 300 were in passenger service by July 2012. The world's first double-decker hybrid bus was introduced in London from January 2007. Transport for London initially stated that it intended to make all new buses delivered for use in London hybrids from 2012. This requirement was later dropped.

Hybrid electric buses use a combination of an electric battery pack and a diesel engine to provide power, and produce around 40% less carbon dioxide (CO₂) emissions than traditional diesel engined buses. Energy generated during braking is used to charge the batteries of hybrid vehicles.

Transport is responsible for around 20% of London's CO₂ emissions; buses make up 5% of the transport total. The city has set a target of a 20% reduction in emissions by the year 2020. Converting London's entire bus fleet to hybrid vehicles would reduce CO₂ emissions by around 200,000 tonnes per year.

Other low-emission buses have also been used in London. Three hydrogen fuel cell powered buses were used on route 25 from 2004, but have since been withdrawn; eight are now operating on route RV1. An ethanol fuelled double-decker bus was operated by Transdev London in 2008 and 2009.

The first hybrid buses to enter service in London were six Wright Electrocity single-deckers. These were ordered in March 2005 to operate on route 360. The buses were unveiled by Mayor of London, Ken Livingstone, on 7 February 2006, with the intention of starting operation on the following day. Later in 2006 the vehicles were temporarily withdrawn from service when their diesel engines overheated.

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Wikipedia