Shock Absorber Gets Power From Bumpy Rides

If your car is going to hit bumps in the road, it might as well get a little power.
At SUNY Stony Brook, mechanical engineering professor Lei Zuo invented a shock absorber that converts the kinetic energy from vibrations into electricity.
Electric and hybrid cars already convert the kinetic energy from braking in to electricity that's used to recharge the car's battery. But in those cases, the energy that's captured is the regular, predictable motion of braking.
Zuo took that idea a step further, and designed a system of gears that collects the energy of irregular motion to ultimately produce electricity. He calls the device a mechanical motion rectifier, or MMR.
"While working on vibration energy harvesting at large scale, I was thinking what is the fundamental challenge? What makes this different from the wind energy technology?" He told Discovery News. "It is the irregular velocity-alternating motion. Then we came up this MMR idea, to convert the irregular oscillatory motion into unidirectional rotation."
The idea of energy harvesting is one that Zuo has been working on for some time. Last year he won an award for an energy harvesting shock absorber that used magnets to generate a small amount of electricity every time they slid past the stationary part of the shock absorber. The MMR setup improves on that idea, using mechanical energy instead of the magnets.
Generating electricity reduces the load on the alternator and engine, which not only drive the car but also power accessories such as the windshield wipers and radio. Generally, a regenerative suspension system could supply anywhere from 100 to 400 watts. A typical car might draw 200 to 300 watts depending on whether the lights or the radio are on.

Removing the load from the engine could save about 4 percent of the gas most drivers use every year, and 8 percent of the gas used in a hybrid vehicle. Recouping the investment in a new part would take three to four years for conventional cars and two to three for a hybrid.
And the MMR is being commercialized, though it won't be on the shelves of your local auto parts store just yet. Harvest Energy, a California company, is working on manufacturing and is speaking to equipment and auto manufacturers. CEO Henry Mariano told Discovery News that the technology could go beyond shock absorbers. It could also be applied to infrastructure as well, so that roads and floors could harvest the kinetic energy from cars and even human steps.