Wherever there is movement, electricity can be generated. We see this in wind power or hydropower, and in the automotive world, in regenerative braking, which recovers part of the kinetic energy during deceleration to recharge the battery. It is not the only movement of a vehicle, because the wheels move up and down on the suspension all the time they are in motion. regenerative suspension The idea of harnessing this energy has been on the minds of engineers for decades… What has happened to it?
The idea behind regenerative suspension is simple enough: traditional shock absorbers dissipate this energy of relative motion as heat, usually by passing oil through valves. Why not try to harness it by using electric generators, which feed energy back into a car’s battery, potentially extending the range of electric or plug-in hybrid cars? There have already been numerous attempts.
Advances in regenerative suspension
The past two decades have seen numerous milestones in this technology, which was patented as an “electromagnetic linear generator and damper” at the end of the last century by Tufts University professor Ronald Goldner and his colleague Peter Zerigan. Since then, many have tried to put it into practice:
- 2004: The audio company Bose announced that it was working on the Bose RideThe system attempted to predict the suspension’s movements and force the wheels to lower themselves so they would encounter the bumps. It reminded us of a noise-cancelling system for wheel movements and was able to recover energy during the recoil of these movements.
- 2005: David Oxenreider won second prize in a design competition Create the Future with a concept almost identical to the design of Goldner and Zerigan.
- 2009: Goldner and Zerigan’s design was sold to Electric Truck, LLCwith a view to commercializing the technology. It didn’t work out… in fact even the company’s website is currently available.
- 2009:Two MIT graduates, Shakeel Avadhany and Zack Anderson founded Levant Power and began marketing the GenShockdubbed the world’s first hydraulic regenerative active suspension. It could actively force the wheels up and down (much like a jack changing tires) as well as extract energy from their movements. They said they were in talks with manufacturers to bring it to market.
- 2013: Levant Power partners with ZF Friedrichstafen AG to bring GenShock to large-scale production… if you take a look at ZF’s website there is not a single mention of it today.
- 2015That year, Audi announced the eROT, an electromechanical rotating suspension system. It sought to improve driving comfort and recover electricity. On a smooth road, it generated just 3 watts. On a bumpy road, up to 613 W… On average, between 100 and 150 W, which were not extraordinary figures, let’s face it.
- 2018Levant renamed itself ClearMotion, bought the Bose Ride technology and raised about $130 million to bring it to market.
- 2020:Audi has once again developed an electromechanical roll stabilisation system, which it calls eAWS. It is used in current high-end cars such as the SQ7, SQ8 and RS Q8. Like the eROT system, it can capture energy and send it back to the car’s battery, but that is not its main purpose, rather to eliminate body roll and achieve sportier performance in curves.
- 2022: GIG Performance presents at SEMA a prototype called Roadkil 5000 which claims to recover twice as much energy as others. Its design makes the stator and rotor rotate in opposite directions to double the spin compared to other rotary units where one would remain stationary.
- 2022In December, CarBuzz revealed that BMW had filed patent applications on a novel flywheel-based regenerative suspension technology. We already know that patents in the automotive industry often simply describe technological ideas… that never make it to production.
- 2023: ClearMotion announced a production order for three million units of its ClearMotion1 active suspension for the NIO ET9, the Chinese company’s flagship. Again, it is a system that seeks to improve handling and driving comfort rather than generating power. Check out its promotional video:
As you can see, the attempts so far have either been unsuccessful or have changed their focus, moving more towards technologies that improve driving comfort and precision than towards truly effective energy recovery technology. Audi no longer mentions them, probably because they do not significantly change the electric range of their vehicles.
What if they have life not so much in electric cars as in combustion cars? According to an article published in the magazine Applied Energya group of Italian, Mexican and American researchers suggest that regenerative suspension could reduce carbon emissions per mile by around 5 g/km. That’s more than 5% of the total CO2 emissions allowed by 2020 EU regulations.
