Prius-style power for London buses

Hybrids to cut carbon in the capital

A new generation of hybrid buses are to hit the streets of London, in the first stage of what is expected to be their largest rollout in Europe. The number of these ultra-quiet, low-carbon vehicles is to quadruple to 56 this spring and reach 300 by 2011 – representing just under 4% of the London fleet.

Their diesel-electric motors will cut CO2 emissions by up to 40% – bringing an immediate contribution to Mayor Boris Johnson’s strategy to reduce the capital’s emissions by 60% by 2025. He has already ruled that, by 2012, all new buses entering London’s fleet should be powered by hybrid technology.

Transport for London is using the introduction as a way to put the latest advancements in technology “through their paces”, explains spokeswoman Vicky Morley. It will be monitoring the performance of the different models, manufactured by companies including Volvo, Wrightbus and Optare, to work out which systems are best suited to the capital. “It might be that we need a combination of technologies for routes with few stops, or longer-distance routes in outer boroughs,” she says.

Debuting on route 141 (London Bridge-Palmers Green) is Volvo’s I-SAM (Integrated Starter, Alternator Motor) system, a parallel hybrid design similar to that already available in cars such as the Toyota Prius. The five-litre diesel engine and electric motor are able to run separately or in parallel in the bus, and an electronic unit controls various functions – including the motor, braking, A/C and hydraulics – to get a 25-30% more efficient fuel performance. – April Streeter

29 May 2009

April Streeter