• Mar 27th 2010 at 12:17PM
  • 70
What if something as simple as a shock absorber could do much more than just absorb the impacts coming from the road? What if the shock could save fuel, charge batteries and even move vehicles down the road? Wouldn't you be interested? We certainly are.

The idea of transferring road impact into energy is not a new one, but this shock is certainly a stand-out. Developed by Massachusetts Institute of Technology students Zack Anderson and Shakeel Avadhany, the GenShock combines the elements of a shock and the ability of a generator into a single package.

Foregoing the complexities, here's what the GenShock made by Levant Power can do. By retaining the energy created from and usually lost through normal shock motions, the shocks can be used to help power various vehicle components. On a traditional vehicle, the stored energy could charge the battery, eliminating the need for an alternator or the energy could power systems like the radio or headlights.

On a hybrid vehicle, the GenShock could send energy to the battery packs, extending the electric range and freeing the engine from some battery charging duties. Here's where the real excitement comes in. On a battery electric vehicle, the shocks could act as gas-free range extenders!

The GenShock is currently enduring testing in a Humvee. After 18 months of of successful testing, the breakthrough shock should be ready for marketing. It's high cost may be prohibitive for passenger vehicles, but the initial market is seen as military usage and transport vehicles. If demand is strong and technological advancements allow, costs could drop considerably and the usages described above could become feasible.

Question: Why don't you plug in your EV at night? Answer: My shocks charge my car, don't yours?

[Source: Green Car Advisor]

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    • 1 Second Ago
      • 5 Years Ago
      "TheTom 3:12PM (3/28/2010)

      The Wh of the ultracaps is negligible compared to the battery pack. It does not need to be a 1:1 ratio. More like a 1:10 or 1:20 as the battery will supply the bulk of the energy, the ultracap only being used during acceleration/braking where power is more important.

      Deep discharge does stress the battery and reduce its life but so does high current drain on the battery pack due to acceleration as well as high charge current imposed by regenerative braking."

      I clearly explained that as long as you configure your system so that discharge and recharge currents are within the specs of the cells there is no damage to the cell, period. A123 cells can do 10C all day, they've been taken to 40C.

      "That is why having an ultracap system taking up the brunt of this from the battery will indeed increase battery life. The battery does not have to be as large because it no longer needs to supply this high current, only whatever current is needed to maintain speed."
      Caps hold seconds of power at best, if you're accelerating hard up a long hill or something those caps will be used up and your battery better be up to the task of providing those amps.
      Also, the battery still needs to be the same size to get the same range, so you save nothing. you need a certain amount of KWH to get your range and caps don't provide KWH.

      " Finally, the weight and space taken up by ultracaps will be small, probably no more than 1/4th the weight and space."

      And if you instead use that weight and space for extra batteries you will get more range and have a larger pack, which means proportionally for the same miles traveled the pack will be discharged less, which is better for the pack.

      "It isn't about saving weight or space. It's about reducing the size of the battery pack and extending its useful life."

      If you reduce the size of the pack and try to get the same range out of it you will more deeply discharge it and shorten it's life.
        • 5 Years Ago
        That's not how it works. The Volt "uses" half the capacity only in that they allow it to reach 50% depth of discharge instead of 90% or so. The whole battery is "used" to provide acceleration and regen, they just don't discharge more than 50% so you only get half the range. Why? Because as I stated deeply discharging a pack will shorten it's life, not because they are "protecting" half the pack from higher C rates. The reason they need to cut the discharge in half is because with a PHEV the small pack means that you will usually use up all 40 miles of range on a daily basis, so the pack will be more deeply cycled on a regular basis, so they have the generator kick on at 50% DOD. An EV with a 100+ mile pack would only be 40% discharged after 40 miles so the stress would be even less.
        In your example regularly using 75% of the pack more deeply discharges it and therefore shortens it's life span.
        As for caps, Jack Rickard of www.evtv.me put about 30 some Maxwell ultra caps in his Gem golf cart and went less than one block before it ran out of juice. These were about as many as he could fit, and it was completely useless. Caps don't have enough energy to do much at all. A better idea might be to couple high C rate cells such as A123 20ah prismatics with lower C rate but higher energy density cells such as SE or TS. The A123's would provide good high power output for a relatively long time compared to caps, and the SE and TS cells provide the energy density, for a much lower cost than caps. But again, if the cells and packs are sized appropriately, there is no need for this. C rates within spec won't hurt the cells, and the C rates of cells are constantly improving.
        • 5 Years Ago
        "Also, the battery still needs to be the same size to get the same range, so you save nothing. you need a certain amount of KWH to get your range and caps don't provide KWH."

        Actually since cycle durability influence automakers (battery makers) on discharge depth, providing a more durable pack would mean you could make is smaller while keeping the same range.

        Take the Chevy Volt, a 16 kwh pack but only using 8 kwh. Why? Because GM wants to be able to provide a 100,000 mile warranty. And one of the fundamental differences between a ER-EV like the volt and a Parallel Hybrid like the Prius, is that the battery must be able to handle the high power output of acceleration and top speed without the need for the gas engine. Using only 8 kwh (out of 16 kwh) of the pack means that wear and tear due to both charge/discharge cycles and high amp discharge will only hurt up to 50% of the pack. And the pack could last twice as long.

        But what if you could reduce the wear and tear from high power charge/discharges (from at least the few seconds of acceleration and regen braking)???

        That means that the Volt could (in theory) use 75% of the pack instead of 50% and still achieve the durability goals. So a 40 mile Chevy volt could have a 12 kwh pack utilizing 8kwh... and thus save 4 kwh (@ $800 per kwh = $3,200)

        Will ultracaps work for this? I don't know, but it is worth a try.
      • 5 Years Ago
      Wow! Magnificent young folks at MIT are pretty impressive. I never thought of it, but why couldn't it provide basically free energy for a hybrid or an EV? Kudos to Anderson and Avadhaney!
      • 5 Years Ago
      A more elegant solution would be to plus the battery into the vehicle's cigarrete lighter.
        • 5 Years Ago
        or put wind turbines on the roof for when you are driving.

        Actually, this idea was really messing with my head last year because uni students in Denmark claimed that they made a wind turbine powered car that went straight into the wind. This is just impossible. What I think they were doing was going into the wind at an angle, like tacking a sailboat, then turning directly into the wind using their momentum.
        • 5 Years Ago
        Given enough wind sure... and given a wind turbine sweep area much greater that the cross section of the rest of the car.

        It of course couldn't drive anywhere practical for many reasons.
        • 5 Years Ago
        not at all. it actually worked. it wasn't powered by its own forward momentum, but it could move straight into the wind, which is absolutely possible. it moved very slowly, but it's possible. think about the physics: given enough wind, the turbine could generate plenty of power to push the car's limited drag forward.
      • 5 Years Ago
      Hm, sounds like it could be expensive, i wonder what kind of results it provides.
      Basically it sounds like it uses hydroelectric power, using fluid motion to drive the generator.
      It may make sense for off-roading applications, but unless you live in pothole central, i think these would do absolutely nothing for most road cars.

      Ah, law of diminishing returns.. how we loathe thee.
        • 5 Years Ago
        I've seen figures given of around 2% for normal roads, 10% for off-road.
        Even for off-road it might not be worth the extra complexity.
      • 5 Years Ago
      The article makes it clear who this product is meant for:

      "MIT's technology licensing office, for example, researched where the device could fit in the market. They found the biggest bang in the biggest vehicles: heavy-duty trucks and military vehicles."

      "To the military, Anderson and Avadhany learned, fuel economy was vital. Powering a Humvee in the field meant more than just buying the fuel; it also meant transporting it there and bringing a protective escort. Anderson said the Marines, incorporating all these costs, price a gallon of fuel at $400.

      Moreover, heat loss presents a vulnerability to enemies who have infrared cameras that can spot panting Humvees in the field.

      "The fact that we're not dissipating energy in those shocks...means that even something like that, fingerprinting the vehicle, is going to get tougher," Anderson said.

      And, of course, there was the all-terrain element: As the ultimate SUV, the Humvee's shocks would surely pulse with energy."

      Good idea though. My first thought was it would involve piezoelectrical generation within the shocks, but using the fluid which is already being pumped around anyway is a small step forward with current shock production. Kudos to MIT.
        • 5 Years Ago
        Ahh, I was thinking we could save allot of money if we did no more road repairs, in such a way we could make these shocks produce more on public roads. ; )
      • 5 Years Ago
      It is very easy to take a simple and effective idea... and blow it out of proportion to be some super gas saving idea or cure for needing a range extender. Like the report suggests.

      I give the MIT guys a lot of credit. And their marketing strategy is pretty good too.


      But lets look at this logically. Then we can get an idea of how much energy this can save.

      Imagine a normal gas car. Getting 25 - 30 mpg on a particular trip. Now what if that same car on that same trip never had to stop at lights, slow down at intersections, etc??? You could essentially cruise much more and only have to worry about initial acceleration and resistance to air and tires. You would expect nearly 80 -90 mpg.

      That is what regen braking does. But of course it is only 70% efficient at recapturing energy and it is not used for every circumstance so a hybrid can effectively get 50 - 60 mpg.

      So NOW, imagine a normal gas car getting 25 - 30 mpg on a normal trip with normal city streets and highway road surfaces. A few pot holes here and there, speed bumps, etc... But that same car with all else equal, would only hope to achieve a few extra mpg if the car were traveling on a smooth piece of concrete the whole way.

      So the estimates of 2% for on road driving make perfect sense. That's 25.5 - 30.6 mpg!!! Sure an off-road Hummer can increase 10% from 18 mpg to 19.8 mpg so that is worth something. Worth the price? Maybe for a military budget sure.

      But with hybrid prices coming down, the easiest, and by far the best place to save, is the regen braking. That is by far the biggest loss outside of the engine.
        • 5 Years Ago
        Since the discussion was regarding regen BRAKING, I am sure everyone knew what he was talking about.

        And he is right in his more "in depth" analysis. I was making a simple comparison so that people could understand where regen braking gets its energy how that compares to the minuscule amount of energy available from regen shocks while on normal roads.

        Even the MIT inventors knew this would only be practical in an off-road environment where fuel savings are critical... the US Military.
        • 5 Years Ago
        Please pardon this slight tangent. On regen braking, I have completely changed my mind on ultra capacitors (Maxwell ones at least) for use in regen braking systems.

        The reason for this is that it greatly eases the burden on, and increases the useful life of your battery pack. It has to do with the high current drain for acceleration followed by a high current charge during braking. Batteries don't like this treatment. Ultracaps, however, love it. So you can use a smaller battery pack (don't have to oversize it so much).

        Argonne Laboratory "researchers estimate that if the size of a PHEV battery could be reduced by about 25%, that would represent a saving of about $2,500. The ultracapacitors and electronics required to make up for the smaller battery size would cost between $500-$1,000."

        Technology Review says that adding such an ultra-capacitor could enable a vehicle manufacturer to use batteries with higher energy density (more energy per liter) and lower power density. "Paired with ultracapacitors, batteries wouldn't need to deliver bursts of power and so could be made with just a few layers of very thick electrodes, reducing the amount of supporting material needed. That could make it possible to store twice as much energy in the same space." [wouldn't be any lighter though]

        • 5 Years Ago
        JustZisGuy said:

        "First off, you do not lose energy AT ALL if you slow down without using the brakes."

        That is completely untrue. But I've read your other posts, and you seem to know what you are talking about so I assume you don't mean literally what you wrote here (I assume you mean you don't lose energy to friction losses from the brakes vs. not losing any energy at all).

        Could you elaborate?
        • 5 Years Ago
        I agree that this article was good until the writer started going off on his ridiculous conclusion.

        The whole "range extender" idea is ludicrous. People are just so easily confused and illiterate that they do not understand the difference between recovering energy from a parasitic loss and acquiring energy from a source.

        People should think, "savings" and "income". Both are nice of course.. but even a thousand "10% off" coupons won't get you the meal for free. In this case, it is more like a single 2% off coupon.
        • 5 Years Ago
        Joeviocoe said:

        "Imagine a normal gas car. Getting 25 - 30 mpg on a particular trip. Now what if that same car on that same trip never had to stop at lights, slow down at intersections, etc??? You could essentially cruise much more and only have to worry about initial acceleration and resistance to air and tires. You would expect nearly 80 -90 mpg."

        That is, shall we say, overly optimistic. First off, you do not lose energy AT ALL if you slow down without using the brakes. So, unless you are completely surprised by every stoplight, or drive like a madman until the last chance to brake, you are not throwing away all your kinetic energy every time.

        Second, I have travelled long distances without stopping, at low speed (50 km/h) in a Toyota Prius, and the best I can get is about 3.5 L/100 km. That's 67 USmpg. (I assume we are talking about statute miles and U.S. gallons here). Normally I get about 4 to 4.5 L/100 km, or 59 to 52 mpg. The ratio is at best 4.5/3.5 = 1.3, i.e. 30% farther on the same energy. Now, some energy is recovered through regenerative braking in a Prius, so the ratio achievable would be a bit higher in a "regular" car. But a factor of 3? I really don't think so.

        Now, take a much smaller car than a Prius, but one which is as aerodynamically efficient, and drive it at a non-stop 50 km/h (32 mph), and you MIGHT be able to get 80 mpg. Maybe. On a good day, downhill with a tailwind.
        • 5 Years Ago
        My only beef with this article is the very last sentence: "Question: Why don't you plug in your EV at night? Answer: My shocks charge my car, don't yours?"

        That is what has everyone here up in arms. You are right that it is a good thing to get back 2% to 10% from driving your EV. The linked source article says 1% to 6% but that's less important than that it also says that for military applications the shocks will pay for themselves in 18 months.

        For vehicles that stay mainly on nice, smooth pavement I don't see a rapid switch to these shocks (takes too long to pay off the extra cost) but for some I see this really catching on. I wish them all the best. And who knows, in 10 years time this may even be mandated (once the cost has been brought down to Earth that is).

        /I still like my joke about needing to jump up and down on your fender 40,000 times in order to recharge your vehicle. Oh well. My comedic genius is not always appreciated... 8(
      • 5 Years Ago
      "Joeviocoe 2:54AM (3/29/2010)


      Although your statement is accurate... "

      Actually, your description shows that his statement was not accurate at all. As you say you have to put money into the bank, (forward motion of the vehicle), to get anything back. If you want to slide down a hill you have to expend energy getting up it first. His statement was wrong.
        • 5 Years Ago
        Vector sums!

        Both forward momentum (the energy source) AND the force of gravity (the bank) must be in the equation.

        Without gravity, there is no return. The car hits a speed bump simply gets bumped into space. And with no gravity, it is unlikely to ever have encountered the bump in the first place.

        And in the case of the pot hole... there is no energy transfer at all. The car glides over the hole with out ever sinking in the first place.

        And without gravity, the car never moves in the first place. Gravity is the force that is required to provide firm and constant contact between road and tire.


        In physics class, you learn about the vector sums of momentum and gravity in dynamic systems. Imagine a car at rest with gravity as a force (arrow) point downward from the center (of gravity) of the car. When the car is in forward motion, another arrow points forward from the same center (of gravity) point as the first arrow. The "resultant" is the vector sum of the two arrows.

        And that "resultant" is the actual line that engineers use to determine the position and geometric placement of the suspension system (to include shocks and struts).

        The heavier the car, the bigger the gravity arrow. The faster the velocity, the bigger the momentum arrow.

        When you hit a speed bump, the shock absorbs energy along the Resultant vector sum of the two. It is not straight forward like John implied, nor is it straight down as "gravity alone" would imply. It is diagonal!


        So in agreement with Letstakeawalk (a rare occurance :P )

        If a car and truck traveling at the same speed hit the same bump, the heavier car would absorb more energy in the shocks. Simply because the "resultant" vector sum is larger due to the force of gravity plays a bigger role in the truck in comparison to the car.
        • 5 Years Ago
        I did not disagree (and neither did letstakeawalk) that momentum will cause the shock to compress. But that is only half of the equation. Gravity is the other.

        Your "space car" analogy takes gravity out of the equation. So lets run the thought experiment with gravity and remove forward momentum out of it (as much as you can).

        A car is pushed VERY slowly up a big speed bump (about 6" high). The spring doesn't compress on the way because of such slow forward momentum. But after you reach the peak, without any pushing, the car accelerates (9.8 m/s2) downward. The contour of the bump makes the direction diagonal (forward and down). At the bottom of the bump, the shock compresses to absorb the energy equal to the energy required to push the car up the speed bump. Not the energy of forward momentum (as that was small).

        Now amplify this effect when talking about off road travel. Hills, boulders, mounts of dirt, etc. You cannot have this effect in space because the "space car" will not travel down the speed bump and gain additional momentum. Gravity is a force that will play a significant part.

        To put in simpler terms. Conservation of momentum is needed. It is the bank that stores your money (energy) for when you want to get it back. Without gravity, a car would experience some shock absorption go up the hill, but not the shock absorption going down... because it would never come down.
        • 5 Years Ago
        Alright John, point clearly taken. You and I are in agreement.

        I disagree with that original statement as well. And your conclusion is sound.
        • 5 Years Ago
        My problem was with his original statement:

        "The energy that is being recovered is not being recovered from the energy used to propel the car (stored in the form of gasoline or electricity)."

        That is an untrue statement. Bumps impede forward motion, and that forward motion comes from the energy used to propel the car. A suspension absorbs the bumps and dissipates that energy as heat, or in this case uses it for regen. In a vehicle with no suspension you'd feel that energy directly. In my examples I removed gravity to prove a point, not to say that gravity has no part at all.
        • 5 Years Ago
        Let's look at the space car again. Even in space it has inertia related to it's mass regardless of gravity. Let's mount the speed bump on a post, that's a million miles long but still connected to earth, so there is no gravity but the bump can't move. Now we'll strap a rocket to the car and aim it at the speed bump such that the tire will ride over it. The mass of the vehicle and its forward motion will cause the suspension to compress, generating energy in the shocks. The car will not just bounce away without suspension compression.
      • 5 Years Ago
      1. The idea is cool, but

      2. The title of the article, and the last line, are absurd and ridiculous. (Perhaps if you added the word "help" before "propel vehicles down the road" it might be ok, but even then - orders of magnitude, dude!!!)

      3. letstakeawalk's comment ("this is electricity that has been created at no cost to the owner - created not by previously stored energy") demonstrates such a fundamental misunderstanding that... well, dude, your credibility on physics-related topics just went about as low as the author of the blog entry.

      4. EVsuperhero's comment that "1 gallon of gas is equal to 33kwhs in stored energy" is accurate (though the unit is "kWh", not "kwhs"). It can be confusing mixing units, even if you stick with metric! Energy can be measured in Joules or Watt-hours (add prefixes to taste); the problem of course is that there are 3600 seconds in an hour.

      Wikipedia is self-contradictory on the topic of gasoline energy density, but I'm sure it's in the right ball park: see
      and http://en.wikipedia.org/wiki/Gasoline
      Let's pick the figure 32.0 MJ/L. That's 32000 kJ/L. 1 J = 1 Ws, so that's 32000 kWs/L. Divide by 3600 seconds/hour to get 8.89 kWh/L. Multiply by 3.785 L/USgallon to get 33.6 kWh/USgallon.
        • 5 Years Ago

        Although your statement is accurate... it can mislead those with an incomplete understanding of physics (99% of Americans :P ).

        Gravity is only a Force as you mentioned. But people tend to regard it as free. It is not.

        Something must add energy to that "gravity potential" and you can only take away as much as you have an "energy sink"

        Even if you live on a mountain and want to go downhill. That energy is given to you by climbing the mountain in the first place. (Or in the case of a rock, the tectonic plates being moved by geothermal energy to give rise to the mountain).


        So gravity is only the bank in which you give YOUR money to... meaning that you must put a dollar in (by climbing the speed bump) and the energy is stored briefly in that bank. You can get it back by letting gravity accelerate you down the speed bump. Same with a pot hole, except that you get a brief acceleration downward first, and then must pay for climbing out of it afterwards.

        ...and normally some energy is wasted as shock heat to make for a smoother ride. So you can get that back now, great. But gravity should never be described as anything other than just a force (or geometry of curved space-time would also be acceptable). And certainly NEVER as a source of energy!
        • 5 Years Ago

        Well, to be honest, nothing should ever be described as "a source of energy", because as well all know, energy can never be created or destroyed, only changed in form.

        The shocks use two forces to do work; gravity, and the forward motion of the vehicle. However, it is my position that gravity plays a greater role, due to the observation that in the absence of gravity, and the presence of only forward motion, no work is done.

        I can also observe, that in the absence of forward motion, work is done by the shocks when gravitational force is applied - ie, adding weight to a transport vehicle. When the vehicle is loaded with cargo, the shocks do work and produce electricity. The energy used to increase the gravitational force is external to the vehicle, and therefore not "recovered" from the vehicle.


        • 5 Years Ago
        "3. letstakeawalk's comment ("this is electricity that has been created at no cost to the owner - created not by previously stored energy") demonstrates such a fundamental misunderstanding that... well, dude, your credibility on physics-related topics just went about as low as the author of the blog entry."

        I appreciate your retraction of this comment in another. :)

        The shocks exist at rest, even when the vehicle is in motion. The shocks only react, when acted upon by an outside force. That outside force is gravity, which either compresses the shock or pulls the wheel down, extending the shock.

        So, the force which increases the potential energy of the shock, which then results in kinetic energy used to do work by spinning the microturbine to create an electrical current, is gravity.

        If someone would care to disprove that gravity acts upon the shocks, and that the shocks are acted upon by some other force, please do.
        • 5 Years Ago
        In physics terminology. The source of energy can be thought of as when can it be first thought of as "energy" and not matter. Fusion and Fission! The reverse is possible also and has been done with particle accelerators. That is gamma ray bursts becoming particle/anti particle pairs.

        So the original "energy cannot be created nor destroyed" phrase was re-evaluated after Einstein's E=mc2. And it would be considered simplistic say matter is energy. For the purposes of precision, Energy and Matter are separate terms.

        There I go babbling again.
      • 5 Years Ago
      start running low on juice, just tell your passengers to start bouncing (or some similar motion) and you'll get home... interesting. apparently sex is now a green way to produce electricity. brilliant.
      • 5 Years Ago
      Another aspect to regenerative shock absorbers; if you use rigid (non-inflated) tires, you will gain in two ways: lower rolling resistance, and you'll get more motion in the suspension (since the inflated tires absorb many, especially of the small bumps).

      You would have to have softer initial spring rates, but I think you would end up with as smooth a ride (or better) as we currently do, and you get higher efficiency from lower rolling resistance, and you regain more energy; that would have otherwise heated the tires/road/shock absorbers.

      And lastly, you would have lower maintenance, because you would not have to maintain air pressure!

      Sincerely, Neil
      • 5 Years Ago
      make roads smoother. problem solved.
      • 5 Years Ago
      "Dampening" is what happens when I spill my beer on you. Damping is what shocks do.
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