Fuel Economy of a Current Hybrid London Bus and Fuel Cell Bus Application Evaluation

London has over 8,500 buses in operation, carrying six million passengers on 700 routes each day. In central London the majority of the bus fleet has been replaced by diesel-electric hybrid buses. In this study, we will investigate the degree of energy efficiency via practical on-road bus performance recordings, forming a foundation for future improvements to diesel and fuel cell hybrid bus design. Research at UCL has investigated the design and performance of the ENVIRO 400H model bus on various different routes in London, obtaining a wide range of data for real world performance. This data includes information on routes, usage, energy consumption and passenger count profiling. Analysis has been conducted on the efficiency of the propulsion system over all the data sets. This knowledge can be used as the basis for developing computer modelling capabilities to in the future to optimize the system performance. The key components in the propulsion system are the diesel engine, generator, converter, battery bank, and traction motor. The energy management strategy has been analysed for different operating conditions and will be discussed in this paper. It was concluded that the system performance varied, with a number of patterns emerging with regards to the engine load and battery State of Charge for providing the propulsion power requirements. The operation strategies employed have been analysed to give a detailed understanding of the operation of the diesel-electric hybrid propulsion system under real-world operation.