An engine that recycles energy generated while braking could lower petrol use and reduce emissions during city driving, its inventors have claimed.
The stored hydraulic energy propulsion (SHEP) system, which will be demonstrated on a Jaguar X-Type, uses electronics and hydraulic pump motors to capture otherwise lost kinetic energy generated during braking.
The system is also suitable for use in buses, trains and special purpose vehicles such as fire engines. During the braking process, formerly wasted energy is captured in hydraulic tanks attached to the vehicle’s chassis.
The recovered energy then powers acceleration when the vehicle moves off from a standstill and requires most power, burns off most fuel and emits the most pollutants. When the vehicle accelerates from a dead stop an onboard computer instructs the pump to apply the stored energy to the driveshaft, moving the vehicle forward without requiring power from the engine.
Once the energy is exhausted the computer instructs the engine to resume normal functions before repeating the storage process as the brakes are once again applied.The result of this is a reduced use of fuel and lower emissions, making the car cleaner and more energy efficient.
Canadian firm SHEP Technologies, inventors of the system, have begun a prototype development programme with Cambridge-based Pi Technology, a subsidiary of Ford which specialises in designing and developing automotive electronics.
The firms aim to develop and install a small, lightweight version of the system in a Jaguar X-Type to create a model that will be used for demonstrations worldwide.’We are installing it in a Jaguar as it is a four-wheel drive car with a limited amount of space for the device,’ said Keith Palmer, project manager for alternative fuels at Pi Technology.
‘We are reducing the system’s size and weight using composites, and need to show it will not reduce cabin or boot room. It must change between systems to produce the smooth ride you would expect from a top-of-the-range vehicle.’The main market will be within inner cities where people do a lot of stop-start driving. However, use on buses and trains is a possibility.’
SHEP Technologies claims that up to 70 per cent of braking energy can be recycled, halving pollution, reducing petrol consumption by 40 per cent and reducing engine and brake wear and tear.
It has held discussions with the UK’s Energy Savings Trust, which showed interest in installing the technology in London’s taxis and Tube trains.
Ford is also involved in another project investigating the possibility of gathering, storing and using energy from braking.
In March, The Engineer reported that Ford and the University of California were researching the use of air hybrid engines, where energy is stored as compressed air. This is injected into the engine and expanded in a chamber to depress pistons and move the crankshaft when needed.
The university’s calculations suggested that the air system could improve fuel efficiency by up to 64 per cent in towns and cities and 12 per cent on motorways.The SHEP prototype should be completed by the end of March, next year.
‘It is very early days for the technology, but we will be interested to see the results of the research when completed,’ said a Jaguar spokesman.