Recent research has uncovered a new potential source of electricity generation in vehicles — the suspension.
Electric vehicle range is restricted by the size of the vehicle’s batteries — a physical restriction because you can only fit so many batteries on a vehicle without taking up more space. However, you can potentially recharge batteries as you go using a couple current technologies.
The main on-board supplement manufacturers have been working with is braking, turning the mechanical energy used to stop a vehicle into electric energy that is fed back into the battery used to power the propulsion motor(s).
Regenerative braking by itself is not overly efficient mainly because it only works when the car is slowing down, which is going to be often in city driving (which is why a 50-km battery range, for example, could turn into an actual range of 60 km or more, a gain of about 20%). However, on an extended highway run, the system depends on those times when the vehicle is coasting to recuperate some energy (estimated at 10% tops, which means a 100-km battery range might be extended by just 10 km).
That’s where suspension components come in (and shock absorbers in particular) — every vehicle has them and they are always working, regardless of speed and even road surface.
Recent research at England’s University of Huddersfield is investigating harvesting energy from the bouncing of shock absorbers to either feed back into the batteries, or to power accessories such as air-conditioning (which use energy that might otherwise be used for propulsion).
As part of his doctorate studies, researcher Dr. Ruichen Wang built a prototype hydraulic shock absorber to investigate the feasibility of such a system, turning the piston action of the shock into rotary action of a generator. He outlined his research and development of his device in an article titled Modelling, Testing and Analysis of a Regenerative Hydraulic Shock System, published in the journal Energies.
“It has resulted in is a truly realisable application for energy recovery from a typical road vehicle,” said Professor Andrew Ball, one of Wang’s doctoral supervisors. “Ruichen developed a theoretical predictive model and carried out the empirical testing, and the two of them correlate beautifully.”
The Chinese national says that under controlled laboratory circumstances, his prototype (which is theoretically ready to be installed in a vehicle) uses a 50-30 mm piston rod to generate 260 watts with 40% efficiency.
The next step is to find an industrial partner to install and test Wang’s system in the road-going vehicle, though the system may also be tested in rail vehicles. Wang has taken a full-time research position with the university’s Institute of Railway Research (IRR)
“We are now exploring how Dr Wang’s energy harvesting and modelling techniques can be applied to developing low-cost self-health monitoring dampers for railway vehicles, a project which already has two industrial partners,” said Dr Paul Allen, who leads the IRR’s Centre for Innovation in Rail.