HORIBA MIRA will lead an Innovate UK consortium to develop CE Power, a hybrid bus run by liquid nitrogen.
HORIBA MIRA’s role in the project will include systems integration, vehicle dynamics modelling and overall vehicle control, to ensure the liquid nitrogen system operates correctly and safely with the diesel engine.
CE Power will run on both diesel and liquid nitrogen, and is said to improve the vehicle’s emissions, efficiency while reducing its carbon footprint.
The liquid nitrogen power source will be primarily used during acceleration away from stationary– when the bus picks up and drops off passengers.
This is the portion of the bus’s drive cycle that traditionally has a heavy impact on the diesel engine and can produce vast amounts of NOx and CO2 emissions.
As a liquid nitrogen expansion engine produces none of these harmful emissions, the technology will enable the bus to continue frequently stopping to unload and pull away from a bus stop without expelling damaging pollutants or greenhouse gases.
While driving at 20 mph or below, the liquid nitrogen – stored in a low pressure insulated cylinder – is warmed up to the point of evaporation, at which time it creates enough pressure to drive the multi-cylinder Dearman engine.
Once the bus reaches 20 mph, the diesel engine will kick in as at this speed the bus requires less effort from the engine to operate.
Technical lead at HORIBA MIRA, Derek Charters commented: “This project presents an exciting opportunity as it will be the first time that liquid nitrogen will be used to fuel a hybrid bus.
“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. 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.”
The benefits of using liquid nitrogen over an electric hybrid bus claim to expect a much longer life, local production and easy refuelling.
Batteries, which power many of the UK’s electric hybrids, require changing several times over the course of a bus’s lifetime, whereas the liquid nitrogen system will last the lifetime of the vehicle.
Liquid nitrogen can be produced locally without the need for neodymium or lithium, which are both used by motors and batteries and sourced from overseas. Furthermore, refuelling liquid nitrogen can take a matter of 10 to 15 minutes enabling the bus to return to the road in a short timeframe.
The project also includes the expertise of the Dearman Engine Company; Air Products; The Manufacturing Technology Centre; Productiv; CENEX, and TRL, and is set to finish in 2016.