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MIT Team Creates Shock That Recharges Your Car
An anonymous reader writes "If you had a GenShock, you may not mind those potholes in the road any longer because this new prototype shock actually harvests energy from bumps in the road to save on fuel. A team of students at MIT have invented a shock absorber that harnesses energy from small bumps in the road, generating electricity while it smooths the ride more effectively than conventional shocks. Senior Shakeel Avadhany and his teammates say they can produce up to a 10 percent improvement in overall vehicle fuel efficiency by using the regenerative shock absorbers. They also already have a lot of interest in their design, specifically the company that builds Humvees for the army are already planning to install them in its next version of the Humvee."
No, I'm pretty sure they'd work in Detroit, too. Especially since I grew up there and drove on those roads for almost 35 years. Let me tell you: if this works half as well as they say in Boston, it'll probably cut your hybrid gas mileage in half.
Okay, maybe that's an exaggeration. But it makes a good glass of lemonade!
Now in the Tampa Bay area where I live now? Probably not so good. Every now and then I hit a pothole and I'm *shocked*.
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I've been saying for 5 years now that we should use all the available energy to power electric cars. Shock absorbers are one step, but combining it with solar cells, small wind generators deployed while coasting, regenerative braking, coupled with supercapacitors and a plug to recharge when necessary, that would be truly innovative.
I think that this is the way of the future, and MIT did one step.
I wouldn't be surprised to see tractor-trailers going hybrid soon. Fuel economy is a HUGE factor for trucking, and they require large engines to maintain speed up large inclines. Additionally, all that weight is very hard to slow down on declines -producing a lot of wear on brakes and power-train (engine breaks). Trains already do it, trucks are next.
"Knowledge is the only instrument of production that is not subject to diminishing returns" -Journal of Political Econom
You do realize that this will only effect hybrid or electric cars right?
Here is some things to consider, in 2006there were a little over 135 million registered passenger cars in the US. Now that's not counting pickup trucks that had to be registered as commercial vehicles but are still used as personal vehicles. Since 2000, not more then 2.5-3 percent of new car registrations have been to hybrid vehicles or electric vehicles until 2007 which saw around 5%. This means that this can effect less then 10% of the passenger vehicles on the road and more likely that number is much lower.
The second thing is, if these shocks produce a gain of around 10% in energy recovered, then we can do some math on the economics of it. If a hybrid electric car gets 60 MPH, Some say on 40, and they travel an average of 1500 miles a month, then we can find how much 10% is worth. So 1500/60 and 1500/40 respectivly come out to 25 and 37.5 gallons of fuel. At $2.00 a gallon, that would be about $50 a month for the 60MPH and $75 a month for the 40MPG. A 10% savings of them would be $5 and $7.50 per month savings. Regular shocks wear out after about 5 years or so of driving, some last around 10 years before they are noticeably shot. So $5 * 12 months * 10 years means this device would only save about $600 and $900 over ten years. That's the price point they have to beat in order for there to be a savings. If they can't get the cost of this stuff under those dollar figures, then they are probably costing more then any savings.
My guess is that their effectiveness is going to go as the shock absorption abilities go and will only be effective for that typical 5 years then severely degrade after that like regular shocks and struts seem to do. The concept doesn't seem to be much different then a wave generator but applied to an existing gas or oil filled cylinder instead of hydraulic pistons connecting floats. This means that they will have to create a valve system and generator and a way to connect it to the cars power inputs. They might be able to do that for less then $6-900 every ten years. But I doubt it.
http://en.wikipedia.org/wiki/Joint_Light_Tactical_Vehicle
The next military truck might not even be from the company that makes the HMMWV. BTW, most of the JLTV entrants (if not all? It might be a program requirement...) are hybrids. The military wants increased fuel efficiency for logistical purposes.
retrorocket.o not found, launch anyway?
I did a ton of shock development as part of my race car engineering job.
We had sensors on the suspension to directly measure suspension travel, with a view towards measuring suspension velocity as part of shock development.
Even on what feels like a perfectly smooth track, there's still a lot of humping and bumping going on.
See http://farnorthracing.com/autocross_secrets6.html for example graphs of suspension velocity pulled right off the car.
DG
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You do realize that this will only effect hybrid or electric cars right?
Given the specific mention of military hummers, which are most certainly NOT hybrids or electic, it must have some benefit for non-hybrids.
Then again, how difficult would it be to replace the starter and alternator with a motor/generator capable of putting power to the drivetrain? Even if it's only a 5hp sustained, that'd be more than enough to take the 1kw each of the six shocks is capable of putting out(1hp=746W). Switch out the lead battery for a LiIon/NiMH of substantially more capacity. Increased cost, but probably actually lighter than traditional systems. For cold areas, there are LiIon that perform *as rated* at -40C. Not the 'put a bigger battery than you could possibly need in warm weather so you still have enough power to start when the oil is like jelly and the battery has 10% capacity left'.
You'd end up with a mild hybrid that can do stuff like shut off the engine at stops. Oh and stick the energy gained from the shocks back into moving the vehicle.
If they can't get the cost of this stuff under those dollar figures, then they are probably costing more then any savings.
The only problem I see with your figures is that they're explicity talking about trucks and other heavy vehicles. So you might want to redo your figures for 12-20 mpg ranges. Their test mule was a heavy truck with six shocks. Indeed, they also mention that it provides a better ride than traditional shocks, so there's a possible selling point there.
20 mpg/15,000 miles=750 gallons. Save 75 gallons a year(10%), that'd be $150@$2 gas, $300@$4 gas. Ten year timeframe? Could save them $3k, more if they've got a really heavy truck or are driving on particularly bumpy roads.
Then again, I've said numerous times that it makes more sense to make trucks and SUVs hybrid before you start making sub-compact hybrids. More fuel to save, more room to put the components, components end up being a lower percentage of the cost of the vehicle, etc...
I mean, look at the typical UPS/FEDEX panel van. Consider it's usage - stop and go traffic all day in the city for most of them. Right now they have a diesel engine that doesn't get turned off when they stop. How much fuel can be saved if you turn the truck into a hybrid? As a bonus, the heavy battery pack in the bottom of the vehicle would help mitigate the tipping hazards of a tall vehicle like that.
My guess is that their effectiveness is going to go as the shock absorption abilities go and will only be effective for that typical 5 years then severely degrade after that like regular shocks and struts seem to do.
Might last longer due to the nature of the energy absorbtion, but you're right. A lot of cost and durability issues need to be resolved.
I don't read AC A human right
Let's respond point by point.
...your 2nd paragraph yields number of cars affected...
You do realize that this will only effect hybrid or electric cars right?
Yes. This will only affect some present and most future cars. Sorry to have disturbed you with it.
Ok, let's agree on less than 10% of passenger cars today. I can add that it affects zero% of my car(s) -- an equally irrelevant fact.
The second thing is, if these shocks produce a gain of around 10% in energy recovered, then we can do some math on the economics of it.
We sure can, and the bottom line is that for 5% of the cost of a $20K car, you can get 10% better fuel economy. [2.5% of a $40K car, 1% of a $100K car, 0.1% of one of these] This "spend 5%, get 10%" thing should already be a clue but here is a back-of-the-envelope calculation anyway: over 150,000 miles, a 25mpg car will use 6,000 gallons of fuel. 10% of that is 600 gallons. At today's price, that is about $1,200, FTW. 5 or 10 years from now it will be higher.
Also, 10% more energy translates to a savings in weight somewhere else. For example, the batteries can be 10% smaller, and a 10% battery weight savings could lead to a further 10% gain. Yes, adding a small "Shock Energy Recovery System" to each wheel would add weight, but most likely not equal to 10% of 68KG. And those 68KG only take a Prius for about 5 miles (currently). The next gen is going for 11 miles of electric-only range, so scale the battery weight accordingly. And that is the point -- if you scale the battery range to 50 miles for example, the weight goes to 680KG, and the SERS savings becomes 68KG since it is not necessary to scale the size/weight/cost of the SERS system.
My guess is that their effectiveness is going to go as the shock absorption abilities go and will only be effective for that typical 5 years then severely degrade after that like regular shocks and struts seem to do.
Bad guess -- electrical systems last vastly longer than purely mechanical systems like a shock absorber. SERS could be an induced system, without physical contact, and thus without wear.
And how about just having an extended vehicle range? If you live 5.5 miles from work, your present day Prius will still have to fire up its gas engine. Add SERS and you don't need the gas. If you presently change the oil every 6 months, now you change it every 6.6 months. And unlike engines, and batteries, the SERS can be designed to not wear out at all -- so you extend the total life of your car, bringing further savings.
I think I'd like to let the marketplace decide, rather than choosing to not offer this product because it might just break even in some initial/present day cases. If SERS causes excitement and optimism, people will want to move toward electric and electric/hybrid systems even more -- and that would bring lower prices and more savings.
The future is in plastics, and SERS-like systems. I find your post well reasoned...for a 1900s buggy whip manufacturer.
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What about cutting out the hydraulic middle man and just have a coil of wire on the shock moving through a magnetic field?
The military is all about electric drivetrains. Stuff isn't necessarily deployed, but they burn a lot of diesel and carry around generators, so they are very interested in things that save diesel or put a generator in every truck.
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