The vehicle, called CE Power, will run on diesel and liquid nitrogen. The liquid nitrogen power source will be primarily used during acceleration from stationary, when picking up and dropping off passengers – typically when buses produce high amounts of NOx and CO2 emissions.
At speeds of 20mph or below, the liquid nitrogen – stored in a low-pressure insulated cylinder – is warmed up to the point of evaporation, to create enough pressure to drive the multi-cylinder Dearman engine.
Once the bus reaches 20mph, the diesel engine will take over.
Horiba MIRA will manage systems integration, vehicle dynamics modelling and overall vehicle control, ensuring the liquid nitrogen system operates seamlessly and safely with the diesel engine.
Derek Charters, of Horiba MIRA, says the project presents “an exciting opportunity”.
“Liquid nitrogen is a fascinating energy source as it can be created in any part of the world from many renewable sources, meaning its carbon footprint is minimal,” he says. “With the UK looking to continue to reduce its reliance on carbon fuels from overseas and the search for buses with reduced emissions, this project takes the UK one step closer to achieving this goal.”
Many of the UK’s hybrid vehicles currently rely on batteries, but these need to be replaced several times – a liquid nitrogen system will last for the lifetime of the bus, and enables refuelling to take place in 10-15 minutes.
Liquid nitrogen can be produced locally without the need for neodymium or lithium, both of which are used by motors and batteries and sourced from overseas.
The project will conclude in 2016. Other partners in the consortium include Dearman Engine Company, Air Products, The Manufacturing Technology Centre, Productiv, Cenex and TRL.