The first diesel buses converted to hybrid power will run on the streets of London early next year

Hybrid-power converted diesel buses bound for London

The first diesel buses converted to hybrid power will run on the streets of London early next year.

The conversion technology was developed by Vantage Power, a company formed by CEO Alex Schey and CTO Toby Schulz. While students at Imperial College London in 2010, they built Racing Green, an electric car that ran the length of America - 26,000km from Alaska to Argentina.

London is introducing an ultra low emission zone in 2020, so diesel buses will have to be replaced or converted to hybrid or all electric power. While the price of fuel is rising, government subsidies are being cut. Vantage Power estimates that switching to hybrid power saves operators around £20,000 per bus per year and operators can have up to 75,000 buses in a fleet. Schulz said retrofitting can convert four old buses for the price of one new one.

New hybrid electric buses cost more than regular diesel buses. Some of London’s hybrid Routemasters, which cost around £350,000 each, have suffered from prematurely failing batteries that will have to be replaced by batteries from another supplier under warranty.

Vantage strips the diesel bus’s engine bay back to the chassis and replaces the contents with its B320 system of a smaller diesel engine, drive motor, generator, battery, electronics and software to manage it. The engine is decoupled mechanically from the wheels.

The B320 has evolved from the two engineers’ student work and continues to use National Instruments’ CompactRio as the ‘brains’ of the system, handling 4981 network variables. “We needed to develop a completely new electronic controller to interface with more than 32 different inputs and outputs, and control more than 13 other devices, to make it the most energy-efficient hybrid bus on the road,” said Schulz.

The CompactRio translates driver commands and constantly calculates the optimal power split between engine and battery for the driving conditions. As well as providing acceleration, the electric motor also acts as a break by regenerating the vehicle kinetic energy and storing it in the battery. The Compact Rio interprets the inputs from the driver’s pedals and converts them into smooth acceleration and deceleration without the driver noticing a delay or the bus stalling.

It can run a ‘geofenced’ operation in which it switches off the engine to run only electric in a zero emissions zone. It reports back data centrally too, so the operator can plan maintenance before parts fail.

Vantage is focusing on retrofits for two models from Alexander Dennis and Volvo that make up 80% of double-decker buses in the UK. It now employs seventeen in Greenfield, West London, and has a partnership agreement with Ensignbus, the UK’s largest bus dealer and a commercial bus operator. Schulz said the retrofit market in the UK was the first target market but it’s “not the end game”. Their ultimate aim is to sell the system to vehicle manufacturers.

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