Energy-Harvesting Shock Absorbers Coming to a Car Near You
Zack Anderson, a former student in electrical engineering and computer sciences at the Massachusetts Institute of Technology and now chief operating officer of Levant Power, holds a prototype of an energy-harvesting shock absorber called GenShock up to a Humvee coil spring where it is installed. Anderson and fellow MIT students developed the technology to not only harvest energy but also to provide better overall suspension for heavy-load vehicles. (Source: MIT)
Elizabeth, this is a great example of how engineers respond to problems to find solutions. That is happened at MIT is not a suprise. MIT has always had a policy that encourages the creation of patents from research at the school. They have a generous program of sharing the revenue with the professors and students. This enriches both the institution and the population. Most other schools do not do this. I have sat through presentations on some very innovative technologies at other schools and find that there is no attempt to patent the technology.
Thanks for the link, J. Williams. I have recently written about an energy-harvesting shoe insert, and this seems like something along those lines. Not sure it's a good application for a car, though! ;)
Indeed, Lou, no surprise about MIT coming up with this. I would say the bulk of some of the most interesting things I coer are out of MIT. They really seem to give their students a wide berth in terms of innovation and guidance. I don't know about this patent program you talk about but if it encourages these technologies to come out of the lab and into the commercial market, that is a real boon.
Ultimately, Rob, I believe the idea is to store the current in the vehicle's battery. But the trick is to make sure the electrical current is usable by the battery, and so they have to filter it first to take out the voltage spikes that the shock aborbers produce. To do that, they probably use voltage regulators.
I don't know for sure, Rob, but I would suppose it's just an extra energy source, reducing the parasitic nature of your electrical features. It's said today that only 15% of the volume of your gasoline tank is used to propel a car forward, so if you have an additional electrical source, it can improve your fuel efficiency. Originally, I believe the idea of items like this one was to use the extra energy to run accessories, such as refrigeration units, on big trucks, particulaly in the military. Judging from what Liz is saying here, it appears to be making the transition to passenger cars now. Seems like it could be used to recharge the batteries in a hybrid or EV, too, but I don't know if that's happening.
Again, I can't say for sure, but I've been hearing that figure for years. I believe it is based on a huge percentage (maybe 60-65%) of the engine's energy being lost as waste heat and friction. The biggest innovation would be to figure out how that waste heat could be harvested.
Yes, if there's one big thing that the 54.5-mpg mandate has done, it's been to push the state of the art in internal combustion engines. It's amazing how many press releases I've seen about more efficient engines in the past 12 months,
That internal combustion engines provide a lot of waste heat inspired my father to suggest mounting a Stirling (external combustion) engine on the exhaust manifold or catalytic converter. He made that suggestion 25 years ago. It is still a good idea.
While we are at this, let's not forget that a lot of the gas in an automobile is used simply to keep the motor running. Cylinder type engines have a minimum speed below which they will not function at all. Any time you are below that speed (except during acceleration), you are pumping 100% of that gas into just keeping the engine from stalling. The vehicle is coasting. Reducing this problem is what a transmission is for. It is also why "instant start" engines have gained favor.
Also, an automatic transmission is a terribly inefficient device. It requires a fluidic clutch. In point of fact, "automatic overdrive" is nothing more than a means of bypassing the fluidic clutch when the engine speed is high enough that the transmission isn't needed.
Great idea for taking a non-obvious energy generation opportunity and turning it into a reality. Nice example of innovative thinking and clever application development that could be a break-through technology in the future.
Thanks Elizebeth for such an informative post , what i beleive is that the bumps experienced by the cars produces voltage and when that voltage is stored in the passenger car produces 100 to 400 Watts however in heavy truckss results in 1KW of energy and that energy is then used to chaarge the batteries of the car .
I agree. This article is very informative and the technology topic is quite relevant. Using the vehicle's mechanics to create energy seems a no brainer. I can see Car Alternator manufacturers becoming disgruntle because of the potential to replace their product with this new energy harvesting based shock absorber. Very interesting article indeed.
Lotta watts on a low-duty cycle does not add up to a lotta energy. We have a 1kW sonar projector that uses about 8 watts on average. If you think you are losing that much energy to your shocks, they would be as hot as pistols after driving down the road. Check them. They might be a little warm, unless you happen to be Baja or motocross racing.
Interesting idea, always good to pursue the edge of technology but this is not ready for prime time because it is very unlikely to produce a positive return on investment. Give me a figure of merit like joules per installed dollar or something so we can evaluate the effectiveness of the system.
Just to clarify something very basic. 1KW is not energy, it is power. If something produces a 1KW pulse of very short duration, it could be an accurate statement to say that the device produced 1KW of "power", but the amount of energy is the product of power and time. For short duration pulses of 1KW, the amount of energy may be miniscule.
So, perhaps these devices produce impulses of 1KW. What is the duration and frequency of them? Is the amount of energy produced meaningful?
If the energy is going to be expressed in terms of watts, a time unit must be involved, such as KWH. Killowatt Hours is a unit of energy. If they state the energy in terms of killowatt hours, it would be more meaningful. It is not meaningful to produce power pulses of 1KW if they are not sustained. On a smooth road, the shocks would not produce sustained power, because they would not be moving on a smooth road.
The terms power and energy should not be used interchangeably. They are not the same thing. Saying that a shock is 1KW is a very deceptive. I want to know how many KWH the thing produces per unit of time, not how much peak power it can produce.
Looking past the confusion over power and energy, 1KW of Power is approximately 1-1/3 HP. So, if a large truck shocks would somehow continually generate 1KW of power, that would equate to about 9HP (based on 6 shocks).
A typical truck would have an engine that produces in the vicinity of 600HP. So, even if the shocks put out 9HP continuously (which they would not, unless the road was continuously bumpy), it would amount to about 1.5% of the power of the engine.
According to one source, new style tires can improve the efficiency of a truck by 7%. Keep your shocks, I'll take the tires.
Putting it in perspective, thats 9 kW on a 'normal' road while the 600 Hp engine is rarely taxed to 100% and doing much less when cruising. These days with fuel costs punishing truckers its never an either/or decision. Note the second value is improved ride thanks to a more complex hydraulic circuit.
The "improved ride" might be applicable to smaller trucks and cars, but they will have an uphill battle competing against air ride suspensions in big trucks. Shocks would be a step back in technology.
Air-ride not only adds comfort, but also road stability. It can level the truck against high crosswinds which is very important along the highway in most of the country. This stability no only keeps the rig right-side up and out of the ditch, but can improve mileage as well.
Thanks for that perspective, Watashi. I don't know much about this air ride technology--do you mean in big tractor-trailer-type vehicles? I know these guys are targeting heavy trucks like Hummers and such. Do they have this air ride already?
Yes - they are pretty much standard equipment on tractor-trailers and large trucks. Smaller vehicles like hummers and large SUVs use springs and shocks, so that is probably why they are setting that as a target.
I remember hearing about this technology a while back. It would be cool if they could get some useful power out of their system and make driving on rough roads worth the trouble :)
I agree, Watashi. It would be nice. I can think of a lot of streets in Chicago that could generate a lot of power with these shocks. The only problem is it would give the aldermen another reason for not fixing the potholes.
I didn't think about that, Chuck...better, energy-harvesting shock absorbers could give lazy infastructure entities a reason NOT to fix the potholes! ;) Where I live in Portugal there are still a lot of dirt tracks people need to drive sometimes...I know these would come in handy for them for sure.
Thanks for the information, Watashi. Now I know something I didn't before about tractor-trailer and truck anatomy. I think this technology can be useful, too, but I suppose we will have to see how it tests and if it ever gets used in a more widespread way.
I sort of question the claim as to the amount of power available from recovering skock absorber energy for one simple reason, which is that in current units all of that bump energy is converted to heat, and the shocks don't get that hot. Of course, there are parts of some roadways where they would easily deliver that much power, but for the most part there would not be that much.
Now 9HP is not much compared to the truck engines maximum delivered power, but it does compare quite closely with the alternator load, so that portion of the assertion is certainly valid. But the cost of such a system could easily be the show-stopper, since it would be a lot more than the present kind of shock absorbers. The description of the additional hardware was not very detailed, but it must be fairly complex.
One more thing is that the present engine driven alternator can charge the battery when the vehicle is not moving, and when it is moving quite slowly. Providing power during very slow driving is vital, especially for vehicles that must traverse Interstate 94 passing Gary, Indiana. Probably there are other roads that have as big a problem, but I am not aware of them.
I question it too, especially on smooth roads. I don't doubt that they may observe 1kw power peaks, but without knowing the duration and frequency of the peaks, that value is rather meaningless. I don't think that the shocks would put out anywhere near 1KW continuously.
In the end, it all matters, though. I'm not saying this is a bad idea, just trying to put it in perspective. You are not going to double the mileage of a vehicle by collecting energy from shock absorbers. If the system reduced alternator loading by some significant percentage, that is still a savings in the end. As long as it doesn't cost an inordinate amount for the savings it could be worth while. If it also improves the ride, etc., those are other reasons to justify the cost.
I checked out the video on their website, and I wouldn't want to drive on the road they are simulating in that test! That would be a kidney buster!
Excellent points, ttemple. The amount of energy gathered needs to be put into perspective in order to be understood. The duration of a 1 kW shock pulse is probably just a second or so -- a very, very tiny fraction of the 24-kWh capacity of, for example, a Nissan Leaf battery. You would need to drive down a washboard road for hours to re-charge your electric car battery that way.
Thanks for the perspective, ttemple, and you bring up a good point that I also want to clarify. I don't think researchers here are expecting to double the mileage, but to power other electronics using the energy harvested. The shock absorbers themselves that they're created also are meant to work better than other shock absorbers out there--ie, cushion the blow more, as you said. I guess it does work better if you're riding on a kidney-busting road than a flat surface, but still I think this technology could be put to good use.
These are all good points to put this in perspective, William K. I suppose the success of the technology won't be proven until there's been widespread testing. The proof, as always, will be in the execution and commercialization--this might be another great idea but just not viable. And you're right, it may end up being cost-prohibitive and not worth the power the system generates.
The comments about recovering energy while walking bring to mind that old saying, "No such thing as a free lunch", which in this case does indeed mean that additional effort would be required to be converted into electrical power by some means. A piezo device driven by shoe flexing would demand a bit more effort to do that flexing, and a device to collect the impact energy would provide some damping of the walking effort. That was the case of the power generating sidewalk presented a while back. The deflection as folks walked on it increased the energy needed to walk on it, so people didn't walk on it as much after a while. So free energy is not everywhere, although it can be found in a few places. Wind, waves, noise, and light. The noise powered generation was first published quite a few years back. Somebody put a big set of loudspeakers on a balcony near the ocean and was able to recover an easily measureable quantity of power.
Wow, it's great to see all the comments on this story! I have been away from the website for a few days but I will catch up soon on all of your comments. I'm glad to see this stirred such a lively commentary and interest from our readers.
Interesting idea. I am curious to know how this shock absorber perform in long single stretch bumpy roads? If they can store energy generated in a continuous bumpy roads then they will be best suitable application will be in a tractor working on a field.
The shock absorbers are still in testig so I guess it remains to be seen how well they perform. A tractor also sounds like a good application of the technology, but I wonder what the energy would be used for on a tractor? I don't know much about how they're built. Are there electronics or other sensors that could use the power?
Like energy harvesting is being successfully invented for commercial use, the government, high way engineers and city traffic departments can think of harvesting breaking energy of vehicles at all traffic junctions. All vehicals come to a halt at all traffic junctions on seeing Red light. This breaking energy of all types of vehicles is absorbed by tarmac of the roads at these locations. The kinetic energy of vehicle is getting wasted out, this need be harvested. By suitably lacing this part of roads with either hydraulic mechanisms or piezo electric panels, it may be possible to convert this otherwise wasted energy for use to supply street lights and traffic lights.
Interesting, gvsreedhar, I never thought about the energy of vehicles when they brake and come to a stop, but perhaps you're on to something here. I'd be interested to see something in more detail about how this can work.