Environment

Award-winning device harvests energy from railway track vibrations

Award-winning device harvests ...
Researchers from Stony Brook University have developed a device capable of harvesting energy from train-induced rail track vibrations to power signal lights, structural monitoring systems or even track switches (Image credit: Lei Zuo)
Researchers from Stony Brook University have developed a device capable of harvesting energy from train-induced rail track vibrations to power signal lights, structural monitoring systems or even track switches (Image credit: Lei Zuo)
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Researchers from Stony Brook University have developed a device capable of harvesting energy from train-induced rail track vibrations to power signal lights, structural monitoring systems or even track switches (Image credit: Lei Zuo)
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Researchers from Stony Brook University have developed a device capable of harvesting energy from train-induced rail track vibrations to power signal lights, structural monitoring systems or even track switches (Image credit: Lei Zuo)

Much of the abundant mechanical energy around us is irregular and oscillatory and can be somewhat difficult to efficiently tap into. Typical energy harvesting systems tend to be built for low power applications in the milliwatts range but researchers from New York's Stony Brook University have developed a new patent-pending electromagnetic energy harvester capable of harnessing the vibrations of a locomotive thundering down a stretch of track to power signal lights, structural monitoring systems or even track switches.

As a train rolls down the track, the load it exerts on the track causes vertical deflection. This displacement could engage a regenerative device like an electromagnetic harvester and generate enough power to operate local railway applications, which is especially useful in remote areas where electrification is not cost effective. Harvesting such energy is much more efficient with regular, unidirectional motion, but track vibrations caused by a moving train are pulse-like, bidirectional and somewhat erratic.

Professor Lei Zuo and graduate students Gopinath Reddy Penamalli, Teng Lin and John Wang from the University's Department of Mechanical Engineering claim to have designed a new harvester capable of converting irregular, oscillatory rail track vibrations into regulated unidirectional rotational motion, similar to the way that an electric voltage rectifier converts AC voltage into DC.

"The U.S. has the longest rail tracks in the world, approximately 140,700 miles; that are often in remote areas," said Professor Zuo. "It is very important but also very costly to power the track-side electrical infrastructure, such as the signal lights, cross gates, track switches and monitoring sensors. Our invention (the Mechanical Motion Rectifier based Railroad Energy Harvester) can harness 200 watts of electric energy from train-induced track deflections to power the track-side electrical devices. By using two one-way clutches, the innovative mechanical motion rectifier converts the irregular up-and-down vibration motion into unidirectional rotation of the generator, thus breaking the fundamental challenge of vibration energy harvesting and offering significant advantages of high efficiency and high reliability."

Impact forces from repeated loading/unloading are also said to be reduced thanks to the incorporation of a flywheel to stabilize the generator. According to Professor Zuo, the technology enables a generator to rotate in one direction with relative steady speed in a more efficient speed region, and changes the negative influence of motion inertia into a positive, thereby reducing mechanical stress and increasing system reliability. Bench testing of system prototypes has resulted in mechanical efficiency of between 55 and 72 percent.

"Such a design not only avoids the challenges of friction and impact induced by oscillation motion, but also enables us to make full use of the pulse-like features of track vibration to harvest more energy," he said.

Professor Zuo estimates that the implementation of such a device could save more than US$10 million in trackside power supply costs for the New York State area alone, together with a reduction of 3,000 tons of carbon dioxide every year.

"If 10,000 units of 200 watt harvesters are deployed in New York State with 20 percent duty cycle, the energy benefits will be 400,000 watts, or 3.5 x 10^6 kWh per year," he explained. "At an average retail price $0.14 per kWh of electricity for the transportation sector, this annual electricity saving will be half a million US dollars in New York State alone."

The team was awarded the "Best Application of Energy Harvesting" at the 3rd Energy Harvesting and Wireless Sensor Networks USA awards held in Washington on November 7 – 8, and has already licensed the technology to Electric Truck/Harvest NRG for commercialization.

Source: Department of Mechanical Engineering, Stony Brook University

17 comments
bergamot69
Hmm, interesting. But as I understand it the vast majority of trains in remoter parts of the States are infrequent freight trains. Would this device be able to generate enough power to send signals down the line to operate signals, switches, etc, some distance ahead of the train (no point on a signal or crossing alarm going on just as the train is passing).
Wouldn't solar/ micro wind turbine/ battery combos be better, as used in the UK for traffic signage?
Mel Tisdale
Worth a quite a bit, I'll bet. Where I live, the metal thieves regularly remove earthing strips from the electified lines. I imagine they would be more than tempted by this little item.
Perhaps a better solution is to do away with any form of light system whatsoever and devise one where the signaling information is superimposed on the overhead power line supply; in much the same way that computer networks use domestic mains within a house today.
Sinnadurai Sripadmanaban
As train traffic is less often,using this on roads will give more output.
Ervin Kosch
How about instead of vibration you use magnets? IE as the train moves by rotate the generator. Now this would only be useful in areas with fast moving trains but I would think that ROI could be greater.
attoman
This a mechanical device which spins up substantial vertical displacements into electrical energy. It presumably has a permanent magnet component and other temperature sensitive bearings, ice and water sensitive elements.
The latter are exactly the harsh conditions remote rail locations will present and this invention is not even begun to be ready for them.
Great that the inventors sold early and have a day job.
ZekeG
Actually it does not have as Attoman assumes, a lot of temperature sensitive bearings and elements. One wonders why you people take a first iteration of a device and mock it so often-you must know all there is to know! It will be housed in a box eventually and bolted intensely to the ties. Solar is not always shining nor wind always blowing-but the trains are most always rolling. Electric Truck has license to this and also has a magnetic shock absorber that converts wasted kinetic energy of shocks into electricity-heavier vehicles work best-adding them on trains, tricks and busses would be sensible and save considerable amounts of fuel. Regen brakes only work when braking shocks bounce continuously.
Patrick Hilke
Sounds like this device might be a good candidate to charge the battery if it could harvest them vertical motion from an automobiles suspension.
Slowburn
re; funglestrumpet
In the USofA most of the railroads diesel-electric propulsion and don't have overhead power lines.
re; attoman
That is a proof of concept prototype but I see nothing that would indicate that it is temperature sensitive, and wrapping it up in a sealed plastic box would keep dirt and moisture out.
Rann Xeroxx
Why not just use solar panels? This device just seems pointless.
Jimbo Jim
"Why not just use solar panels? This device just seems pointless."
try to stand by the track when a moving freight train passes by, the up & down motion is tremendous, since each rail car weights a few tons, the up & down motion on the rail is unreal, it can turn out some serious serious energy, either hooking up a motor or a spring loaded magnetic coil to move against some rare earth magnets planted solid to the ground totally stood still.