Go-Ahead London has taken delivery of the first 39 Enviro400H double-decker buses with Series-E hybrid technology supplied by Alexander Dennis Ltd (ADL) (www.alexander-dennis.com) and its technology partner BAE Systems (www.baesystems.com).

Using ultra-capacitor energy storage to further reduce life-cycle costs, this next-generation hybrid bus has achieved Ultra Low Emission Bus (ULEB) certification, with 37% lower greenhouse-gas emissions than conventional diesel buses.

Series-E still uses the hybrid system architecture — proven in over 1,300 existing Enviro400H hybrid buses — in which the diesel engine only acts as a generator to produce energy for the electric drive system.

However, it now uses a lighter and more compact direct-drive permanent-magnet traction motor, which no longer requires a speed-reducing gearbox, thereby increasing efficiency and minimising wear.

An ultra-capacitor energy storage system replaces the previous generation’s batteries. Designed to last the lifetime of the bus, this ultra-capacitor storage will reduce the total cost of ownership by not requiring mid-life replacement.

Due to this and other improvements, a 53% reduction in the cost of parts and consumables is predicted over a 10-year period.

Richard Harrington, Go-Ahead London’s engineering director, said: “With 245 Enviro400H buses already in our fleet, we know that these new vehicles will help us to improve London’s air quality.”

Colin Robertson, ADL chief executive, said: “We are delighted that Go-Ahead London has taken the bold step to embrace innovation with these orders. We appreciate the trust placed in us and our technology partner BAE Systems.”