A Flexible Way To Convert Waste Heat To Electricity (asianscientist.com) 134
A research group in Japan has developed an inexpensive, large-scale and flexible thermoelectric generator (FlexTEG) that has high mechanical reliability and can convert heat into electricity efficiently. The findings are published in the journal Advanced Materials Technologies.
From a report: Thermoelectric conversion is one of the most attractive techniques for converting low-temperature (150C or lower) waste heat into electric power. However, widespread adoption of this technology has been hampered by a lack of suitable packaging techniques for thermoelectric generation modules that can operate in the 100-150C range. In addition, the production cost of modules for generating power at room temperature was prohibitive.
In the present study, scientists at Osaka University, Japan, have developed a method to manufacture thermoelectric generation modules in a cost-efficient manner while preserving the conversion efficiency of the modules. They mounted small thermoelectric semiconductor chips on a flexible substrate and were able to achieve reliable and stable adhesion of the electrical contacts between the chips and the flexible substrate. They called their invention FlexTEG.
In the present study, scientists at Osaka University, Japan, have developed a method to manufacture thermoelectric generation modules in a cost-efficient manner while preserving the conversion efficiency of the modules. They mounted small thermoelectric semiconductor chips on a flexible substrate and were able to achieve reliable and stable adhesion of the electrical contacts between the chips and the flexible substrate. They called their invention FlexTEG.
Re:World saved (Score:5, Informative)
If you read the actual paper [wiley.com], you will see that this process delivers a whopping 1.84% efficiency.
The Carnot efficiency of generating power from low grade heat is terrible, and then you slap a very inefficient Seebeck semiconductor thermoelectric generator [wikipedia.org] on top of that, and about the best you can do is recharge your Apple Watch from the waste heat from your furnace.
This is not the solution to global warming.
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Good. For a moment I was worried about the fate of the 2nd law of thermodynamics.
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Good. For a moment I was worried about the fate of the 2nd law of thermodynamics.
It's only a law until someone learns to break it. The 2nd law will be the 1st one we learn to break.
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Sigh, would you kindly explain what the second law of thermodynamics has to do with the topic? I'm keen to learn ...
Re:World saved (Score:4, Informative)
Could still be useful for many devices that don't need a lot of power. Sensors for example, where they only need to take occasional measurements (many things just don't change that fast).
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I wonder if you could power your Kindle in this way with room temperature.
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Because marketing and vendor lock-in.
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I wonder if you could power your Kindle in this way with room temperature.
No. It would be a much bigger story if it were merely heat powering this- that would be rewriting the laws of thermodynamics (which I bet will be modified one day). You can't get energy from heat- currently that goes against what we know of physics. You CAN get energy from heat differential. For now, heat by itself cannot be converted into any other form of energy.
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For now, heat by itself cannot be converted into any other form of energy.
That is a bit nitpicking as you pointed out before: You CAN get energy from heat differential.
But your claim is wrong anyway ... of course you can convert heat energy to anything you want, problem is: you can not harvest all of it in one step.
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It's 1.84% efficient at a temperature difference of 105K.
I.e. You can't use it to power anything used by creatures made out of protein who are not wearing a full-body heavy-duty protective suit.
Protein coagulates at around 70C. Pain threshold for humans is around 50C.
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If you read the actual paper [wiley.com], you will see that this process delivers a whopping 1.84% efficiency.
The claim of 1.84% efficiency doesn't seem useful. I think the more relevant measure is 158 mW per square centimeter, or 15.8 watts per square meter, given a temperature difference of 105 (C or K).
Key questions: how much does it cost, what are its maximum and minimum operating temperatures, and how long does it last? "... TEGs are reliable, environmentally friendly, have a long lifetime ...." but I don't know what "long" means.
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It's not 15.8 Watts per square meter. There are 100x100 square centimeters in a square meter.
It's 1580 W/m2.
Price or how long it lasts are pointless. TEG in case is a product of a lab experiment. As in "laboratory conditions".
You'd need to be boiling one side of it while keeping the other side of it on ice in order to generate that meager amount of power.
I.e. Under environmental conditions NOT found in nature.
The kind that humans and most their electricity-using toys can't survive without heavy temperature
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It's not 15.8 Watts per square meter. There are 100x100 square centimeters in a square meter. It's 1580 W/m2.
You're right, of course. I lost a few decimal places among the millis and the centis. Thanks for the correction.
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It happens.
A few months back I was positive that 1mg per 1ml is a 1:1 ratio. Which is just... dumb.
The next day I woke up with a fever.
Furnace waste heat to power Apple Watch? Optimist. (Score:2)
Delta T for this generator is 105 K.
In other words, to get that 1.84% you need to put one side of the TEG on ice, and then boil the other side of it.
The module exhibits a maximum output power density of 158 mW cm-2 at dT = 105 K, corresponding to an efficiency value of 1.84%, which is comparable to a conventional bulk TEG.
On the other hand...
Average surface area for adult men IS 1.9 m2 or 19000 cm2.
Meaning that human body wearing a full-body TEG-suit would produce ~3000 Watts if doused with gasoline and set on fire.
I only hope Apple users record themselves powering their devices that way. So the rest of us could laugh at them longer.
I can many industries adopting this (Score:5, Interesting)
Automotive industry: There is a continuing push to improve overall mileage of a car. If waste heat can be captured as electrical power, It will get adopted.
Power industry: These guys are already trying to up their efficiency and the competition is stiff. If the power industry can implement this it will get implemented real fast.
Industrial processes: These guys vent so much waste heat it isn't funny. But they do have space normally. I can see them intentionally re-tuning their discharge temperatures to take advantage of this. Many of these industries are (also) very competitive. If they can shave a couple tenths of a percent of their costs, they will do it.
I expect most people in the industries I mentioned will not immediately notice it. But one of those industries will see it and get it implemented. And then Ford or Chevy or Subaru will come out with a car that doesn't have an alternator in it. All of the electrical power is generated from a rebuilt radiator and exhaust system that recycles the power from the heat. A lot of alternators on a car can draw 1-2 hp. So that is now either top end power or additional MPG. Either way everyone else in the industry is now saying "how do we do that?"
I expect the same thing to occur in industrial process, only the average consumer will never hear of it. In metal refining their price per ton will drop by a penny or two consistently and everyone else will start asking how they managed to shave that much cost off without reducing anymore many power.
In either case, once this gets adopted in a particular industry, everyone in that industry will stampede to adopt it so they can stay competitive.
Do the arithmetic (Score:5, Interesting)
> A lot of alternators on a car can draw 1-2 hp. So that is now either top end power or additional MPG.
You're correct there. The alternator needs to be able to produce about 1 HP of electricity. At 1.8% conversion efficiency, a TEG would need 56 horsepower (42,000 watts) of heat in order to generate enough electricity, in the lab. Do you think your engine wastes 56 HP as tailpipe heat while cruising around? Even at full throttle?
The car uses about 20 HP to maintain cruising speed. Is it wasting three times that amount as heat? Probably not. Let's say it's wasting 5 HP as tailpipe heat.
Obviously blowing the exhaust through "radiator" (heat exchanger) isn't going to make the exhaust cold. It'll be out almost as hot as it went in. Perhaps we can recover 1HP, on a brand new vehicle in the lab. We need 56HP, we only got 1HP. Oops.
Now go look in your tailpipe. See the soot? Notice all the rust and everything on the bottom of the car after a few years of driving? That'll probably cut efficiency in had again, so we end up getting about 1% of the power we need.
Thanks though.
Or walk by your tailpipe (Score:2, Redundant)
Another way, perhaps simpler than the math and making assumptions about waste heat, is to try this simple experiment:
Walk by your tailpipe with the car running.
Does it feel like a 42,000 watt heater to you? In other words, did you get cooked when you walked by?
Re:Or walk by your tailpipe (Score:5, Interesting)
Another way, perhaps simpler than the math and making assumptions about waste heat, is to try this simple experiment:
Walk by your tailpipe with the car running. Does it feel like a 42,000 watt heater to you? In other words, did you get cooked when you walked by?
why would you try to sequester waist heat at the coolest part of the exhaust system on a ICE vehicle?
the exhaust manifold even at idle can reach hundreds of degrees F. Go down the pipe a little further and you have a heat mill called a catalytic converter
The average light off temperature at which the catalytic converter begins to function ranges from 400 to 600 degrees F. The normal operating temperature can range up to 1,200 to 1,600 degrees F. But as the amount of pollutants in the exhaust go up, so does the converter's operating temperature.
Seems to me to a pretty good place to put some of these to me.
1600F would be about 3033 kelvin/watt [K/W].
the exhaust manifold usually in the 700 to 1000 degree range depending on the load on the engine.
now you have another 1895 kelvin/watt [K/W]
so that's almost 5 K/W of wast heat that can be tapped for free.
just saying that you're just looking at the wrong places to look.
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Probably you meant kW and not K/W, too?
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According to the calculations, TheRealQuestor just meant K, not K/W or kW. There is no way to calculate the amount of power you can extract when only knowing the temperature difference. The calculations shown do not produce a meaningful result.
Re:Do the arithmetic (Score:4, Interesting)
The car uses about 20 HP to maintain cruising speed. Is it wasting three times that amount as heat? Probably not. Let's say it's wasting 5 HP as tailpipe heat.
Probably: yes.
A car uses an internal combustion engine. Those have efficiencies (in that horse power range) of about 19%. So: 80% of the power is exhausted as heat.
Obviously that all changes with hybrid drives etc. So bottom line you are right, but the idea of your parent was neat anyway, perhaps a bigger battery (many pure combustion driven cars have an oversized battery and regenerate energy during braking because the over all electricity demand in a modern car [e.g. AC] is s high that regenerative breaking saves fuel) and a smaller alternator will work fine.
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All of the ones that "autostart". When you stop at a light, the engine shuts down to save fuel. It will start the car so quickly when you touch the gas that you won't even notice it. It will also "engine brake" when you step on the brake.
I had a girlfriend with one a few years ago. It was amazing.
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I've ridden in a few of these cars. One friend had a BMW that did this at every traffic light. It was certainly noticeable and quickly became irritating.
While it does offer a marginal improvement in efficiency, I think this is just another attempt to put lipstick on the pig that is the internal combustion engine. Best to just get an electric car that doesn't have to deal with an idling engine, clutch, transmission to match the poor torque curve, inefficient combustion process, Rube Goldberg emission control
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I own one, a 2016 Skoda Octavia wagon, base model.
When idling it burns 0.5L fuel an hour, so it's not shutting down to conserve fuel.
It turns off to reduce emissions (and I get 10% cheaper car insurance because of this).
I find the stop/start (which is able to be turned off) to be fine, doesn't bother me at all unless I have the aircon on, which in Australia, is often.
And getting 4.7L/100km on highways and 5.3L/100km around the city is pretty impressive. In British MPG that's 60mpg and 53mpg respectively. In
Re: Do the arithmetic (Score:2)
You missed the point. Some ICE cars recover energy from regenerative breaking to recharge the battery. Saves using crankshaft power which then boosts efficiency a small amount. What I like to call the Sir Dave Brailsford method.
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Waste heat isn't just heat, the reality is you are looking at an unused temperature difference. Getting energy out of waste heat means generating energy by cooling that heat. Depending upon how low a temperature you can achieve will affect how much energy you can extract out of that temperature difference. So using a very low boiling point liquid and low temperature water, you can create a low temperature steam turbine running on that low boiling point liquid. Low temperature climes can make much more effec
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I think we have reached "peak ICE". New ICE car sales have been flat for two years. EV sales are accelerating rapidly. Hopefully the transition will happen quickly.
Re:Do the arithmetic (Score:4, Interesting)
The efficiency of your average car is about 25% so yes, it does waste three times as much as heat.
Re:Do the arithmetic (Score:5, Interesting)
Ues, lets do the arithmetic!
Buring a gallon of gas produces 120,000,000 Joules.
Lets say we are cruising at 60mph and using 20hp (15kW).
Lets say the car gets 30mpg.
You burn a gallon of gas in 30 minutes, or 1800 second. (67kW)
You are generating 52kW of waste heat.
Here is the break down (Score:3)
Reality: An ICE engine
Lots of different hot places. Car in a bubble? (Score:2)
You didn't mention the catalytic converter, which gets very hot. You did mention several places that get hot - where heat is dissipated. Unless you put the entire car in a bubble of transducer material, you're not going to capture most of that heat.
You're right you'd probably get the most electricity by wrapping the radiator in this material. Of course then the radiator would stop working and the engine would overheat. You'd need to make the radiator about 50 times larger to offset that.
Where this technolo
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BMW has been working on this for years.
https://www.greencarcongress.c... [greencarcongress.com]
Hyping it 10 years ago. In another 10 years ... (Score:2)
Yeah I see they've been doing PR pieces on it for over a decade. Hopefully in another decade or two it'll be an option on one of their vehicles. That would be cool.
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The car uses about 20 HP to maintain cruising speed. Is it wasting three times that amount as heat? Probably not. Let's say it's wasting 5 HP as tailpipe heat.
Automotive ICEs are 25% efficient or less, and it takes about 20-25HP to cruise on the freeway. I'm shit at math and even I know you're off by miles.
Now go look in your tailpipe. See the soot? Notice all the rust and everything on the bottom of the car after a few years of driving? That'll probably cut efficiency in had again
System efficiency is one thing, powertrain efficiency is another thing, powerplant efficiency is still another thing. You've got them all con-fused.
However, this whole debate is stupid, because the alternator is about to go away. It will be replaced with a mild hybrid motor-generator. It needs to be there anyway, because it's going to be used to start the car,
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Considering the average ICE care engine is probably less that 30% efficient, it's probably wasting about 50 HP as heat, although not all of that would be going out the tailpipe.
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Automotive thermoelectric generators [wikipedia.org] ARE a thing... but from what I can tell they've been at the prototype stage for decades.
Also, not needing to be flexible, they are more efficient. Komatsu's TEGs can pull off about 7% efficiency, with their dT at about 250K.
Or about 1 Watt per square centimeter.
At least 50-60 years, yep (Score:2)
> but from what I can tell they've been at the prototype stage for decades.
Yeah they've been a hot new thing for at least 50 or 60 years.
Maybe one day they will actually have practical application.
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Hi Ray.
Your calculations seem roughly correct for what they are describing. I think I I can help you find more waste heat than you have found.
The Bugatti Veyron (base model) generates 3,000 horse power when in operation. Of that 3k horsepower, only 1k horsepower can be captured and put to use as kinetic energy.
Where did 2k horsepower go? Mostly to various radiators to get rid of excess non-kinetic (read: thermal) energy.
I think it is possible to find waste heat to convert into electricity. :)
So close. Not the base model (Score:2)
> I think I I can help you find more waste heat than you have found. The Bugatti Veyron (base model) ...
Darn, so close! It would be fun to tinker and see how much waste heat we can actually capture, but unfortunately mine isn't the base model. :)
On a more serious note, such a car can produce a lot.of horsepower *for a few seconds*. After a few seconds it either just goes to roughly 0 HP, or the driver dies and it goes to zero.
Either way, you can only put about 20HP to the wheels for an appreciable amoun
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Companies that produce non-stop SUV's and Trucks are pushing super super... super..... super... hard to reduce emissions and improve gas mileage!
reduce the perception of emissions (Score:3)
They don't reduce emissions. They reduce the perception of emissions by the public.
The cars didn't reduce emissions the last 20 Years in real mileage, only on paper.
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Holy shit, I have to pepper my posts with disclaimers and mark every sarcastic sentence made in jest. The exclamation point should have given it away.
I can't spoonfed people enough.
WTF happened to our schools? I know, ha ha, that's an age old saying but seriously? People don't even get SARCASM anymore? The lowest form of rhetorical devices there is. God forbid, someone watch a British TV show. It would blow their minds.
And to spoonfeed more, I'm not smugly condensating. I'm voicing my frustration. It's like
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For cars I think the size and weight would outweigh any benefit. For EVs there is much less waste heat, and it's difficult to use it to heat the battery. The main problem is that the battery needs heating and cooling at different times, and it's hard to shunt that heat around in a way that you can switch on and off and which doesn't add a lot of complexity or weight. All current models use a heat pump or simple PTC heating element.
Why generate the waste heat? (Score:2)
Automotive industry: There is a continuing push to improve overall mileage of a car. If waste heat can be captured as electrical power, It will get adopted.
A far better solution is to use EVs which don't generate anywhere near the amount of waste heat in the first place and already get vastly better fuel economy. It is almost always a better idea to not generate the waste in the first place than to generate it and try to recapture the waste. Instead of trying to reclaim a few extra percent waste heat, work on fast charging for EVs which has a FAR greater long term ROI.
And then Ford or Chevy or Subaru will come out with a car that doesn't have an alternator in it.
Don't need an alternator in an EV so that's already done.
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Power plant industry (and trucking) are going to look at this technology and going to snap it up. I have shown the math elsewhere in this thread. But they can get a nominal 1% power increase out of this technology. Both Power
Cars are not efficient (Score:3)
So you have pushed the problem upstream to the power generation plants.
You say that like its a bad thing. Power generation plants are far more efficient right out of the gate than even the best car engine.
And I'm ignoring the fact that you can put solar panels out and cut the power plant out of the loop altogether.
(solar power doesn't have the efficiency yet to drive cars around full power on solar cells).
What are you talking about? There already are people powering EVs with 100% solar power. That's not even a question. A typical large roof can provide more than enough energy to power an EV for typical driving needs. Larger solar farms can do even better.
The power plants currently generate lots of waste heat
Power pl
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Power plants do not generate waste heat at 100K heat differential. Their waste heat is at less than 20K. You can fix that by removing the last turbine stage, then you'll get decently hot steam out that you can use this invention for. However, that will cost you at least 5 percentage-points of overall efficiency, and you are gaining less than 2 percentage-points back using this invention.
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This is a Russian troll attempting to dissuade thoughtful posters from active forums.
It has got crap efficiency. (Score:3)
Less than 2% if I read the article right. Which is almost 10x worse than other existing systems.
Sure it bends, but the efficiency is so crappy it's only useful for novelty applications.
Re: It has got crap efficiency. (Score:1)
Lol calling someone out for pedantry because your own pedantry was shown to be wrong!
Re: It has got crap efficiency. (Score:4, Interesting)
Too bad their efficiency sucks. I've worked a lot with them, they've gotten quite cheap in the last few years. The first one I bought to experiment with was $22. Now you can get ten for about that. You can thank the public for dropping the price on them with their demand for those 12v portable coolers that plug into cigarette lighters.
What a lot of people didn't realize though is the little buggers draw about 2 amps of power (at 12vdc) to create a ~ 30 degree temperature gradient. Which isn't really that much, and it generates 25 watts of heat (plus whatever heat it's moved out of the cooler) on the external heat sink, so it really tends to warm up its surroundings.
Only VERY recently have I seen much in the way of reverse-use. You can buy cell phone chargers now that you sit by the campfire when you're out on a camping trip, to charge your cel phone with the power of the camp fire. Not all that efficient, but in that setting, efficiency isn't important, as you're sitting next to a stupidly large wasted heat source (where cooling isn't an issue) anyway.
I'd like to see this tech evolve more than finding new packaging for old technology. They need to find something besides the peltier. Efficient waste heat energy recovery and universal material recyclers are the TWO technologies that can change the world in the way the transistor did. So I'm not sure if I'm happy or sad to see this - yes it's better than what we've got now, but you're just rehashing old tech rather than finding better tech. This is the "acorn tube / nuvistor" of its time. We don't need better tubes, we need something better than tubes.
Here is where you are missing it (Score:2)
I think I can .. (Score:2)
.. I think it's trivial, that its just a different version of the well known peltier effect based heater/cooler units you use when buying a cooler for keeping beverages cool when underway.
Because of the "250 pân" pairs from the abstract this is how peltier cooler/heater pads are built up, and I think you can already get around 0,8 % effeciency with commonly availiable off the shelf components.
You can use these modules yourself to extract electric energy from a temperature differential.
IEEE Junichi Nishizawa Medal for the Inventors (Score:1)
According to the research paper [sci-hub.tw] describing the new thermoelectric generator, it resulted from a joint effort among researchers at the University of Osaka, the Technical University of Denmark, and E-ThermoGentek Co., Ltd.
These researchers deserve the IEEE Junichi Nishizawa Medal [ieee.org]
Oven == Power Plant (Score:1)
I can't wait to charge my phone with my oven! Who knew frozen pizzas could save the wortld?!?
Datacenter application? (Score:1)
Package it right and put it on every cpu heatsink and psu in a datacenter. As long as the parts are cheap enough, cutting power usage in a large datacenter by 2% could be huge.
Wrong tempratue range (Score:2)
Since most data centers run in the 65-85F range, the cooling systems run chilled water in the 40-45 range. The work required to get the temperature of the rejected heat up to something u
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As long as the parts are cheap enough, cutting power usage in a large datacenter by 2% could be huge.
They aren't. These suckers are always too expensive to be of any practical use in power generation outside of niche applications where nothing else will work. For example, the wood stove fans that are basically two heat sinks, a motor, a fan, and a peltier junction between the heat sinks. One sink sits on the stove, and the other radiates the heat taken from the other side of the junction. That is advantageous because you don't have to bring in a wire, so it solves a real problem.
So one possible application
That's nuts. (Score:2)
Package it right and put it on every cpu heatsink and psu in a datacenter.
That's nuts. You're burning power to pump heat to cool those CPUs.
Even if this thing, the air conditioning system, and the electrical system, were a perfect carnot cycle prime mover, refrigerator, and supercondicting wiring with 100% efficient electronics, you'd be burning every watthour generated by the device to cool the cold end of the thermal scavenger to a temperature lower than that of the CPU's heatsink. It would be a wash (e
Why auto companies don't do it already (Score:3)
Auto companies, for decades, have been playing around with thermoelectric recovery of power from internal combustion exhaust heat as a replacement or supplement for the alternator. They'd LOVE to replace that pack of moving parts, wearing bearings and slip rings, and fan-belt wear, with a quiet, solid state, black box that pulls the necessary power "for free" from otherwise wasted heat, rather than sucking down a horsepower or two (when the battery needs its starting and pre-start energy consumption replaced) and lasts the life of the car - or at least the muffler or catalytic converter.
But this won't do it. It's less efficient than the peliter cells they've already tried, and its big advantage is that it is thin and can flex, which isn't needed in a car.
The last two improvements in electric generation for cars were the result of semiconductor technology: The replacement of the double-wound, commutator-rectified generator with the diode-rectified alternator, an the relay-and-buzzer electromechanical regulator with a semiconductor regulator (currently built into the alternator).
The main advantage, which got these deployed as soon as the semiconductors were up to it, was that the alternator could generate enough at idle to immediately pick up the operating load and start replacing the battery power used to start the engine. Generators needed the higher RPMs of driving to replace the starting power. This drastically reduced the depth of discharge on the battery, lengthening its life, and also avoided the scenario of running the battery down if you have an in-city driving cycle composed of just short trips. (The other advantage was that commutators and relay-regulators wore out, requiring regulator replacement and generator rebuilds occasionally during the life of the vehicle, while slip rings on an alternator can last until the bearings also fail.)
A waste-heat scavenger doesn't generate substantial power until the exhaust system is up to temperature, or close to it. That would put you back to the lots-of-short-trips-kills-the-battery scenario if you replaced the alternator with a heat scavenger. It would be even worse, because you'd still be powering the running loads off the battery even as you drive away. So you still need the alternator.
By the time the scavenger is putting out, the alternator would typically have replaced the starting power and any pre-starting energy use, and be just running the operating loads. 3/4 horsepower is close enough to a kilowatt as not to bother with the difference, and your typical vehicle's run power is well below that, so (even with its slight inefficiencies) it's not putting enough running load on the engine to make much difference So far, peltier cells (apparently better than this invention) haven't been attractive enough as a fuel-saver to justify their expense.
There are other issues too. (Like increased complexity and opportunity for failure, whether they can stand the heat levels needed to scavenge significant power, and the vibration to last the life of the car without an expensive repair.) But the above lack of improvement on an alternator seems to me to be enough of a killer in itself.
Having "free" energy available doesn't mean the value of the-amount you can collect and put to good use will exceed the direct and reliability risk costs of collecting it.
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But it doesn't have to do it all by itself. The critical issue is cost. If it can add a kW at steady state to a battery pack, then it'd be a great addition to a mild hybrid vehicle, where all the loads that used to be belt-driven are now electric.
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If it can add a kW at steady state to a battery pack, then it'd be a great addition to a mild hybrid vehicle, where all the loads that used to be belt-driven are now electric.
But a hybrid's engine is already hooked up to an even more efficient alternator, and normally running in the most efficient part of the engine's operating range. This particular heat scavenger is horribly inefficient - and it produces a drop in the bucket compared to what the engine/genny combo is putting out.
Get something that can g