Inventor: Shakeel Avadhany, Zack Anderson, Zack Jackowski, Ryan Bavetta and Vladimir Tarasov
Time: 2 years
Is It Ready Yet? 1 2 3 4 5
The idea for an energy-producing shock absorber started humbly enough, just another wild invention tossed out during a late-night dorm-room bull session. Only, the students involved were among MIT's best, and they actually went ahead and built it. Two years later, they've got a shiny Hummer H1, loaned by the manufacturer to use as a rolling testbed, and their GenShock may soon find its way into the military's fleet of Humvees.
The team — Shakeel Avadhany, Zack Anderson, Zack Jackowski, Ryan Bavetta and Vladimir Tarasov — came up with a way to harness the energy generated by the up-down motion of a vehicle's shocks as they compress over dips, bumps and potholes. The power that the GenShock system produces lets the alternator, which is driven by the engine and provides electricity to charge the battery, do less work. And that, ultimately, saves fuel.
They began by creating a simple hydraulic system, in which the shock absorber's piston pumps fluid to drive a hydraulic motor and a miniature electric-motor generator. The team's first prototype generated a total of 800 watts of continuous power with four shocks, and up to five kilowatts — about seven times as much as a typical car alternator produces — over nasty off-road terrain. They estimate that their next version could double the generating capacity, boosting fuel mileage on paved roads by 2 to 5 percent in commercial trucks and 6 percent in military vehicles, which when fully armored can slurp diesel at a dispiriting four to eight miles per gallon. Hybrids, which can store GenShock electricity in their batteries, would gain the most — up to 10 percent.
As a retrofit for large commercial trucks, "the system could pay for itself in fuel savings in a little over a year," Avadhany says. Although paved roads generate less shock movement, the regular high-frequency oscillation can still produce useful power. And as a bonus, the invention could potentially provide better performance and handling when coupled with a computer sensor system that reads the road and varies resistance over the shocks.
MIT's licensing department showed interest in acquiring the technology, but in 2007 the group decided instead to incorporate as Levant Power. Later, one of their professors brought their work to the attention of Paul J. Kern, a retired four-star army general and the president of Humvee manufacturer AM General. He wanted further evidence of GenShock's electricity-generating potential. "It started as, 'Let's see what you can do,' " Avadhany recalls. "We weren't expecting them to ship us a Hummer in the mail." When the device showed promise in tests, a lucrative development contract followed.
Working between classes from a rented warehouse and makeshift office in South Boston, the team outfitted the hulking SUV with the GenShock system and data-acquisition gear. During 500 miles of real-world testing, they began replacing existing components with custom miniaturized parts to scale down the shock's size and weight and generate more power, while meeting the military's sky-high standards for durability and performance. The system must last the lifetime of the vehicle, operate effectively when submerged in water, and limit electrical noise that could cause interference with other equipment.
The group is now speaking with the Office of Naval Research; the army's Tank Automotive Research, Development and Engineering Center; and truck builders such as Navistar and Mack Trucks. If any of those groups put in an order for the GenShock system, the inventors, now all graduated, won't even have to send out their résumés. "This is it," Anderson says. "This company is our job."
"The power that the GenShock system produces lets the alternator, which is driven by the engine and provides electricity to charge the battery, do less work. And that, ultimately, saves fuel."
The only way for this to save fuel is if the shaft for the alternator is completely disconnected from the belt-drive system on the engine. Adding a clutch to the alternator would reduce the mechanical energy but not eliminate it, either. So if the engine is still needing to rotate the shaft in the alternator, even if the electrical drain is nil, how would this allow the alternator to "do less work... and that ultimately, save fuel"? It makes no sense.
envoid: when electric load on alternator is high, you need to put more power to rotate it at the same rpm. When I turn on full lights and windshield heating, rpm at idle drops a little, because these systems DO use some electricity.
I am a catamaran boatbuilder and am wondering what you have done in regards to using this system to harness wave energy both as part of a boat's propulsion system and as a stand-alone generator.
Why not generate power from the wind that travels beneath the car somehow. We use wind power already so why not use what a car generates automatically?
The answer to your question is simple: the larger the load, the more difficult it is to turn the alternator shaft.
The shaft is turned through a magnetic field which sets up an electric field which makes a current in the coil of the alternator. The faster you turn the shaft, the larger the current. This current in turn generates another opposite magnetic field around the coil. This pushes against the original magnetic field, which makes it more difficult to turn the shaft.
Of course, the larger the load the more current is needed and the more difficult it becomes to turn the shaft. It's called Lenz' law, but you'll need to understand Faraday's law first. Add these new current generating shock absorbers and the alternator doesnt need to work so hard.
So even though disconnecting the alternator mechanically is best (because you would overcome friction), disconnecting a load (like a battery or lights) would also increase engine power and thus decrease fuel consumption.
I so want these for my Zap Xebra electric truck, can they be had or is this just a one off?
Here's the problem that everyone seems to be missing,to wit:
more parts = more parts to break.
question: How much more complex is this system? It's installation, either after market or at the factory? It's servicing, maintenance, repair, replacement of individual components, or the system as a whole?
question: How much more EXPENSIVE is this system?!
Observation (and, kiddies, these are the concerns of a proffessional mechanic with 30 years experience on MULTIPLE vehicles, airframes, and assorted systems/subsystems):
There are trade offs to be had with every system installed in any vehicle/craft/vessel. When you make a car with a more impact survivable cabin to reduce the number and severity of injuries, you eliminate the overall survivability of the car itself. When you make a craft, any craft, more fuel efficient, you sacrifice power. And, when you introduce a new system/subsystem to enhance the capabilities of the unit as a whole, you drive the per/unit cost, and the cost of maintaining said unit across its lifetime, through the Ionosphere.
Where does it end? Is it really worth installing a $2,000 power generating suspension control system for a meager (at best) 10% increase in fuel efficiency? (and that's on the tiny hybrid!) And remember, boys and girls, the bigger the vehicle, the more shocks, the more complex the system, the higher the cost. Add that to the simple physics demanding heavier, sturdier shocks and electronics for a Peterbuilt versus a Prius.
It's an interesting take on the fuel consumption conundrum, but how does making a car or truck more complex, more expensive, and (let us not forget, folks) HEAVIER, equate to making it more economical when you're obviously pumping more greenbacks into it, not only from the start, but for it's entire useful cycle?
Analysis: Impractical. If the system could increase the fuel efficiency of, say, a Kenworth pulling a lowboy trailer with a 50 ton caterpillar excavator chained to it by an estimated average of 10-15%, now that would be impressive. Then the fuel savings for smaller vehicles, or those with significantly smaller loads, would similarly be much higher (say, perhaps 25-30%), but at the current projections it's not actually saving any money.
a wind powered generator below the car would only increase the wind resistance and load the engine would have to pull
The alternator is regulated by the charge in the battery. If power is being put into the battery via the shocks, then the draw on the alternator will be less and the power drained by the alternator will be less. More fuel will be used to motivate the vehicle. Economy (mpg) goes up.
Wow! Do you mean this?
"When you make a craft, any craft, more fuel efficient, you sacrifice power."
You have gotta be kidding! What is streamlining all about then? What is a tune-up for? What is less weight for?
There are a few real gaps here. If it is possible to get 200W from a shock absorber, then the shock must be currently dissipating 200W as heat. Seems to me if I put a 200W light bulb inside a shock housing it would blister the paint within a matter of minutes. As shocks normally run a few degrees above ambient in normal driving, it seems unlikely that they are dissipating 200W. Also, all the energy that could be recovered from the shock must come from the engine. Tapping more energy from the shock will load the engine further, with the claim that the energy is returned to the battery (maybe, but with rather high losses) - perpetual energy, anyone? All this equipment adds vehicle mass (don't forget about the capacitor bank (?) needed to smooth the power output). Any possible gains will be offset at least to some degree by added weight. Finally, what does one do with the recovered energy once the battery is fully charged (which won't take long), dump it as heat? Doesn't the shock already do this rather well?
A SHOCK ABSORBER OPERATES BY ABSORBING ENERGY. WHEN THE WHEEL HITS A BUMP IT IS DRIVEN, BOUNCED, UP, AND THE HEIGHT IT BOUNCES IS CONTROLLED BY THE ENERGY ABSORBED BY THE SHOCK ABSORBER, THEN THE SPRING DRIVES THE WHEEL BACK DOWN, AND THE SHOCK ABSORBER DISSIPATES SOME OF THE REBOUND ENERGY.
SHOCK ABSORBERS HAVE ABSORPTION RATINGS, SUCH AS 20% JOUNCE, 80% REBOUND OR 50% JOUNCE, 50% REBOUND, SO CALLED 50/50 SHOCKS. WITHOUT THE SHOCK ABSORBER THE WHEEL WOULD KEEP ON BOUNCING. WHEN DRIVING OVER UNDULATING ROADS, THE WHEELS ARE IN CONSTANT UP AND DOWN MOTION, THE SHOCK ABSORBERS KEEPING THEIR MOTION DAMPED SO THE VEHICLE DOESN'T ROCK AND ROLL UNCOMFORTABLY.
THE DAMPING ENERGY IS DISSIPATED AS HEAT AND IS REMOVED BY THE RELATIVE AIR FLOW. THE DAMPING ENERGY COMES FROM THE ENGINE AND IS THROWN AWAY. THE GENERATING SHOCK ABSORBER CONVERTS THE WASTED ENERGY INTO ELECTRICITY RATHER THAN WASTING IT. SHOCK ABSORBERS DO HEAT UP AND LOSE EFFECTIVENESS, THAT IS WHY RACING SHOCKS SUCH AS ON MOTO-CROSS MOTORCYCLES HAVE COOLING FINS AND COMMONLY, REMOTE RESERVOIRS WITH FINS.
RACING BICYCLES WITH SHOCK ABSORBERS OFTEN HAVE A SHOCK LOCK-OUT FEATURE BECAUSE THE SHOCK ACTION ABSORBS POWER FROM THE RIDER. LOCKING OUT THE SHOCKS ON SMOOTH SURFACES MAKES PEDALING EASIER. IN OR OUT DEPENDS ON THE TRAIL OR PAVEMENT CONDITION AND THE RIDER'S PREFERENCE. THE TIRES, DEPENDING ON PRESSURE AND LOAD, HAVE THE ABILITY TO ABSORB MINOR BUMPS THAT ARE NOT BOTHERSOME TO THE RIDER.
I am not questioning whether or not shock absorbers dissipate energy, the question here is one of magnitude. The 200W claim seems rather high for ordinary usage.
I don't disagree either that one could draw 200W from a shock, but it would be the equivalent of putting a rim-drive generator on a tire and claiming that one was tapping a free source of energy. As soon as you draw more power than the shock normally dissipates, the shock system is a parasitic load, not an energy source.
Since, in my experience, the heat dissipated by a shock is rather low under normal road use, the possibility of offsetting the added weight of the system (fluid, lines, motor, generator, electrical stabilization system, wires, controls, hardware, etc.) with energy recovery within the normal shock energy envelope is very low.
And, what do you do with the energy recovered once the battery is charged? Now you are limited by the power consumption of the car, as you have nowhere else to dump the recovered electricity.
Would this technology work well with commercial delivery truck EVs?
I am a subscriber to Popular Science after reading and enjoying the article
"10 Audacious Ideas to Save the Planet".
I would like to share an idea I have had for many years.
this "idea" was sent several years(5) ago to Mr. Fred Salvucci of MIT and Ms J. Meejinn Yoon of MIT 2 yrs ago
I have had this idea for a long time.
It could have multiple uses. But, "only an idea" after a car is actually moving.
The energy that a vehicle produces along a road, highway by simply moving over the road way, that is, the "weight" of a vehicle pressing down on a liquid (hydraulic) = pressure. The liquid is stored within a apparatus.
The apparatus is buried in the road/highway. Pressure is independent of pipe size,. so a lot of pressure can be generated just by the weight of the vehicle passing over the apparatus and compressing the liquid.
What can it be used for? (a lot of things) to help generate either or both electricity and/or pressure (900Pounds per sq. inch), for an alternative
source of electricity.
An example, it could generate electricity at roadway rest areas to charge the newer multi fuel cars.
This apparatus could easily generate 900 lbs. per. sq. inch to help in desalination in Florida
Common sense is the key to an infinite storehouse of knowledge
While commenting on the Gen Shock system a number of people have commented on the process of energy generation using an alternator and the losses associated with this. Also discussed is whether shocks dissipate energy. The real issue we need to address is that the energy is being generated by using Gravity and what is the most efficient way of generating this energy wasting a minimum on actually absorbing the shock in a shock absorber. Can anyone throw light on this?
Re:Comment by John Cusick
I am wondering that in case such a system is built under the roadway; what would be the right way of using this stored liquid or to generate enough energy which is cost effective, perpetual and easy on capital costs and operation costs.
TANSTAAFL, There's So Such Thing As A Free Lunch. If I understand your liquid-under-the-roadway idea, it is the equivalent of rolling along on a hose, say a firehose, to compress a liquid. Since there is work being taken out of the hose, work must be put in. This work comes from the engine. Imagine rolling a wheel along a smooth surface, then imagine rolling it along a full garden hose connected to a sprinkler. You will find it harder to roll the wheel along the garden hose. Yes, you can do some work (push water out of the sprinkler) with the water being compressed in the garden hose, but thanks to the first law of thermodynamics, the total work you get out of the hose will be less than the total extra work you do to compress the liquid (there will be heat losses, accounting for the difference). In no case can more work be gotten out than is put in.
I think Tslothrop gets it about right questioning the power output. In any normal suspension system there is some dissipation of energy through heat. That is the energy available here for recovery. If you are driving down a Michigan city road or an some rutted track your shocks will be do some extra work controlling the ride. If your going down a German autobahn or the salt flats, there is not much energy expended controlling the ride.
If one is seeking recovery of major wasted vehicle energy, you go for recovering braking energy (ie: typical hybrids -hydraulic or electric) or air resistance because they are sizable chunks.
Cant fault people for thinking outside of the box, but this doesn't seem much of a gain. Especially factoring in the other trade-offs mentioned above.
Liquid under the roads...hmm, I don't think so. Besides the physics problems we have not yet mastered potholes and trains yet.
Shock absorbers are energy converters. They normally convert kinetic energy (on compression) and stored spring energy (on rebound) into heat that is lost to the atmosphere. If the damping needed to control vehicle wheel suspension can be created by drawing electrical power from it, it will be energy recovery that can translate into better fuel mileage. Just making roads smoother would have a similar effect. For reference, it is a fact that off-road trucks driven hard can melt the PU (polyurethane) bushings out of the mounts -- now that is HOT!
Just read Cowboy82's comments on the negatives about genrating power from shock absorbers. He is correct in that the more complex the system the bigger the opportunity for having problems. However, as a Professional Engineer for 30 years these comments are very shortsighted. Anything new and/or more costly or complex must undergo the rigors of Cost/Benefit analysis justification. Reducing energy consumption on the order of a few percent is HUGE. The answers to the energy crisis is that no one source of energy improvement will solve the problem but instead a combination of many improvements including smaller ones like this. The evolution of technology development as it matures are simple then complex and as it matures becomes less complex from a user perspective and more refined from a manufacturing concept. The reliability of many items that we have today is orders of magnitude better while being more technically complex that it was previously. TV sets that go for years witihout service and cars that go for extended periods of times without major repairs are more the norm now than the exception. I personally have had 2 vehicles that went over 400K without any major engine work or drive train work. Both vehicles likely would have gone much longer had they not been subjected to 3rd party accident. Although they have a considerably higher level of technology that previous vehicles have had they performed at a level that was unheard just a few years ago with less complex technology.
it is always amazing to me how people can think themselves so smart...without being able to read.
Some people say that it is not possible to generate sufficient power to be worthwhile, others that it will cost too much, still others that it is not possible to increase efficiency without sacrificing power.
Let's take the last first. Imagine a corvette with a metal frame fastened to the roof holding a king-size mattress with its broad face towards the nose of the car and its edges hanging over each door. Now imagine an identical, stock car without the mattress and frame. Both cars will have exactly equal power - exactly equal. One car will be more fuel efficient. I can even make the first car equally fuel efficient by taking off the mattress and frame. Look, I did it without sacrificing power! I've broken a law of physics or something! Sheesh. Get real. It is easily possible to make something more efficient and more/equally powerful at the same time. Make the engine block out of a titanium allow, for example, and water-cool the block. Now use the steam from block-cooling to generate electricity and ditch the alternator entirely. The car gained more power from losing the alternator drag and more efficiency from the lower weight. This kind of thing should be obvious.
Other people are saying you can't generate more energy than would be dissipated by the shocks as heat. This is sort-of correct. You can't generate more energy from shocks than would be dissipated by the CAR as heat from sources that the shocks can harness. Most shocks, even the good ones, pass on some of the vibration to the frame. This is dissipated as heat by the frame, but with a more sophisticated shock could be harnessed for energy production.
Those who assert that the shock couldn't generate 200w should say what they mean: Pop Sci and the inventors are lying about their results. You should realize that giving off 200W doesn't mean that you have to be as hot as a 200w bulb. The glass has a thermal conductivity different than metal. This means that it has to heat up more before the heat it gives off is in equilibrium with the heat it absorbs from the filament. The comparison is just plain wrong. "A few degrees" above ambient can easily be enough to dissipate 200w...depending on how much energy is passed to the ambient environment per second.
as for the energy coming from the engine and thus this system must provide extra load in order to generate this energy is committing a logical fallacy. Yes the energy comes from the engine, but it is already loaded on the engine - right now, the load is there, but wasted as heat. This invention takes the existing load and puts it to productive use. It is exactly the same as water-cooling the engine block and generating electricity with the steam. It's not a free lunch, it's making use of your resources more completely and thus more efficiently.
Cowboy82 goes off on how this is overloading a vehicle with needless complexity and includes "where will it end" derision. What he misses is that this is not a NEW subsystem - it is a different subsystem. We take away the old suspension and give it a new suspension. Nothing is added that isn't taken away.
The new system may, perhaps, be more complex. It's hard to know - some shocks nowadays are microprocessor controlled already. But you and the others who insist that this cannot be worth the trade offs clearly did not read the article - it specifically said the system pays for itself in cost over a period of one year on some vehicles, thus it lowers total cost of ownership, it doesn't increase it (at least with appropriate applications). Also, the contract specifies that the system has to last "the life of the vehicle". That's a heck of a lot less maintenance than current shocks!
Finally, smooth roads won't do the same because the engine itself vibrates the car, and this system generates energy out of movement of the frame whether induced by the engine or by the ground.
Read the article and think critically b4 commenting!
Bicrip, your suggestion of using steam from the process of block cooling isn't very well thought out.
1: The extra heat from the engine is already used, it's used for heating the interior in the winter, and for A/C in the summer.
2: And perhaps a bit more to the point: "use the steam from block-cooling to generate electricity and ditch the alternator entirely" generating electricity requires a generator, which is basically what an alternator is.
This kind of thing should be obvious and think critically before commenting!
I have not seen a comment regarding the Piezo electric generation addressed in the patent for this new shock/gen system. The Piezo crystal only requires pressure to produce high voltage electricity which is transferred to battery after regulation. The pressure on the shock is already there and is not increased by the piezo system, thus no increase in resistance or heat. Am I missing something here.
Piezo has to be the most efficient source of energy on earth. Pressure = voltage. Ed