A design for a liquid-nitrogen-powered vehicle engine could provide an alternative to batteries and fuel cells

The engine developed by Dearman Engine Company (DEC), which is driven by the pressure created as liquid nitrogen (LN2) returns to its gas form could provide a way of powering a vehicle without producing CO2 tailpipe emissions but with a longer range and faster refuelling than a battery.
A proof-of-concept model has already been used to power a car at more than 50 km/h with only cold air in the exhaust. DEC now plans to develop a commercial prototype then to assess its feasibility. DEC told The Engineer that forklift trucks may be the first potential route to market. Toby Peters, DEC director says that “Because of regulations and emissions, [forklift trucks] already have a high penetration of battery technology, around 60%. ….. If you want to operate a fork-lift truck inside a building it needs to be zero-emission. Our product is likely to be, on a cost-base, more competitive to a piston engine than a battery, and piston engines are massively cheaper.”
In the DEC engine, a heat-exchange fluid such as anti-freeze and water are injected into the head of the piston just before the LN2 is injected. The LN2 stays all the way up to the piston, and all the expansion takes place inside the cylinder. The isothermal expansion ensures that the temperature remains the same, which is highly efficient.
Using LN2 as a fuel has the advantage of relying on an existing distribution infrastructure and could be particularly efficient as fuel for refrigerated delivery trucks. It could also be generated in remote places using renewable energy sources and a small liquefaction plant. DEC recently won The Engineer’s Technology and Innovation Awards Grand Prix for its utility-scale liquid-air energy-storage system. DEC hopes to secure sufficient funding to develop the technology commercially from 2013.