How to Charge Your Cellphone Using Wasted Heat 214
Ilya writes "Companies such as BMW are investing in Thermoelectric Generators to make their cars more efficient by replacing the alternator. Thermoelectric Generators convert wasted heat from the engine into electrical power. This green instructable shows how you can use the same technology right now at home to harvest expelled heat from home appliances to charge your cellphone and other gadgets. Also features a lego racer powered by the roaring flames of a tea candle."
BWM? (Score:2, Informative)
Re:BWM? (Score:5, Interesting)
Seriously: major typo in the summary, folks.
Many years ago, I worked with an ad exec who had (much previously) pitched a campaign to BMW. His agency lost the bid to another agency, even though they thought they had an innovative ad concept. Some months later, he was reviewing the posters and realized they had printed "BWM" in multiple places, in very large type, and nobody at the agency had noticed prior to the presentation. Ooops.
Re:BWM? (Score:4, Interesting)
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BWM makes awesome cars (Score:2, Funny)
Re:BWM makes awesome cars (Score:5, Funny)
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Correct. Quartto transmissions are incredibly rare. But you could try using a Quattro transmission as a replacement
I charge my cellphone while riding my Carnot cycle (Score:5, Funny)
I like to work out in my rec. room with various exercise equipment. My favorite? The Carnot cycle (http://en.wikipedia.org/wiki/Carnot_heat_engine)
I just hop on and convert all the waste heat in the room to useful energy
He wasn't much good at spelling either.. (Score:2)
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I just hop on and convert all the waste heat in the room to useful energy
If you're doing exercise, it'd be a Carnot heat pump, n'est-ce pas? One end would get cold, and the other hot...
Wish I could harvest the power from my farts..... (Score:3, Funny)
Re:Wish I could harvest the power from my farts... (Score:5, Funny)
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I guess farts are funny anymore.
Sipping From a Firehose (Score:4, Informative)
Given that the average American consumes 13,500KWh per year [nationmaster.com], getting a couple of Watt-hours into your phone from wasted heat instead of the grid isn't going to make a damn bit of difference.
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Re:Sipping From a Firehose (Score:5, Insightful)
Re:Sipping From a Firehose (Score:5, Funny)
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Are you being serious or facetious?
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Re:Sipping From a Firehose (Score:4, Funny)
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Because that costs a couple extra cents per unit and causes people to call in because they can not set there clock or return them to stores because they are two complicated. Same logic as to why they still sell microwaves with just a dial. People are generally stupid and making a commercial product requires it to be idiot proof.
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Yeah, just like homophones!
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Like this? [apple.com]
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Personally, I'd like both less-pedantic and fewer pedantic people :)
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And finally, just to annoy you some more, there's a split infinitive in the first sentence of this post.
Are you trying to taunt PitaBred into further pedantry? I'm sure that you are familiar with Fowler's discussions of split infinitives, e.g.,Robert Allen, ed (2002). "Split infinitive". Pocket Fowler's Modern English Usage. Oxford University Press, quoted in http://en.wikipedia.org/wiki/Split_infinitive [wikipedia.org]
Re:Sipping From a Firehose (Score:5, Insightful)
Additionally, such waste heat might not actually be "free" - depending on some of the implementation details.
The engine works by generating heat and then converting it to mechanical motion while dissipating that heat to a cold sink. If you don't "waste" that heat by sending it to a cold sink then the engine operates less efficiently.
Again, it depends on the details - the energy might be "free," or it might just rob the engine of power just as an alternator does. You can't get around the laws of thermodynamics, though...
Re:Sipping From a Firehose (Score:4, Informative)
I worked at Toyota for a while we have been talking about this for at least a year. The technology has been around for a long time, but we usually call them thermocouples. It's exactly the same concept, except they need to be much larger, and have a much higher temperature differential to be useful. The main problem is the size and weight. The weight is significant when you're looking to reduce mass to improve fuel economy, and obviously it adds cost to the vehicle.
As for extracted heat reducing the efficiency of the engine, after heat leaves the cylinder head, unless it is used to do work (as in a turbocharger) it is waste.
Re:Sipping From a Firehose (Score:4, Informative)
Currently automotive engines use a radiator to get rid of excess heat (internal combustion engines generate quite a bit of unwanted heat) usually the combination of a fan, and the movement of the car through the air, serve to cool the radiator so that it can accept more heat from the engine. Without a radiator the car would quickly overheat, which can cause (among other issues) cracked heads and/or engine blocks.
The alternator currently makes the engine work slightly harder (using more fuel and generating even more heat) to create electricity. By replacing it with a device like this which does not require the work of an alternator, and using the abundant "waste" heat, a vehicle would be more fuel efficient, and as an added bonus, the cooling system would be more efficient.
The bigger question than whether the engine will be more efficient or not, is whether the extra efficiency gained outweighs the extra costs and complications, and whether the new system can generate enough electricity to power all the accessories and charge the battery, especially on short trips on cold days where it takes longer for the engine to warm up (and therefore start producing electricity) and where the load demanded to start the engine drains the battery further.
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Again, it depends on the details - the energy might be "free," or it might just rob the engine of power just as an alternator does. You can't get around the laws of thermodynamics, though...
Thoughtful reply, but it's still likely to be significant. Personally I'd instrument the fool thing to save a few years of controversy, i.e. measure the total effect on an engine with and without this mod. Of course that would be an empirical approach and might offend the theorists (grin).
I'd also like to think of whether you could get away with a smaller coolant pump if you transferred some of the engine's waste heat through this mechanism rather than simply dumped it through the radiator. I'd also be
Heat exchanger and solar clothes dryers (Score:2)
If you're living in a cold climate, the exhaust from the dryer ought to go to a heat exchanger to help heat up your house.
If you're living in a hot climate, it's a waste of energy to use anything other than clotheslines and drying racks.
Re:Sipping From a Firehose (Score:4, Funny)
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About 1.21 gigalols.
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Yes, since we can't solve the problem in one step, we should never proceed
To restate your premise:
Given that the average American drives 8500 miles per year, spending one day a month bicycling to work isn't going to make a damn bit of difference.
Re:Sipping From a Firehose (Score:5, Informative)
OK fine I will run the numbers for you:
One day a month is statistically significant at around 3%.
My cellphone battery is 3.V, 750mAh, or about 3Watt-hours capacity. Emptying/charging it every week of the year gives about 150Wh consumption then, compared to 13,500,000Wh an American uses a year, or about 0.001%. This is statistically insignificant.
Hopefully that makes things a bit clearer for you.
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and going to electric power steering
Why would electric power steering help? If you've got enough torque to run an alternator, you've got enough torque to run a hydraulic pump.
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One person clapping in an audience of 2,000 doesn't make a damn bit of difference. So why do you bother to clap?
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Most "eco-friendly" energy sources in fact either cause the same amount of pollution per energy unit or often more, such as biodiesel, ethanol, geothermal, and most wind farms barely break even after huge investment and CO2 emmissions from building them. Solar-thermal is the best renewable source for truly beneficial energy production (except for hydro-turbine of course). All other eco-friendly power projects are just political boondoggles.
In case you're wondering - boondoogle: a project funded by a gove
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Maybe not.
But if we added up all the ideas we are tempted to dismiss due to apparently trivial benefits, we'd probably see a worthwhile dent in overall usage.
At last! (Score:5, Funny)
finally someone invents a use for the formerly useless lego mindstorms thermal sensor. Use it to let your mindstorms bot find a recharging stations
laptop heat? can that be used to charge it self? (Score:4, Funny)
laptop heat? can that be used to charge it self?
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but you will get longer life out of it then?
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Yes, you will get longer battery life if you turn some of the "heat" into electricity. There are some problems to look out for, though. The thermocouples don't really convert heat into electricity. It's the temperature difference between the hot and the cold side which creates the electricity, so you have to have a heat source and a heat-sink capable of sinking the heat without warming up too much. Since the cool side has to stay cool, the temperature difference between the air and the heat-sink is low, whi
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Keep the hot side hot and the cool side cool... don't tell me McDonalds had the secret to providing a minuscule increase in energy efficiency and only used it to make a crappy burger! [wikipedia.org]
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What's with all the McDLT references as of late? Is this a new internet meme?
That was a fucking delicious burger though.
Re:laptop heat? can that be used to charge it self (Score:4, Funny)
Re:laptop heat? can that be used to charge it self (Score:5, Funny)
That heat is traditionally used for roasting nuts
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Regenerative breaking?
Does that mean hitting it with a sledgehammer recharges the battery?
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It's also worth noting that these heat-to-electricity units impede the flow of heat. Just like putting a dam with a turbine in it makes the water levels upstream go up, a peltier style generator would increase your laptop's temperature.
Hopefully, the generator will provide the extra energy needed to power all the extra fans you'll need.
Thermodynamics (Score:3, Interesting)
This is something I never quite grasped from physical chemistry class. Obviously you can reclaim some energy from heat, but you can't reclaim it all, as that would break the 3rd law of thermodynamics. How much energy can you actually reclaim from a given amount of heat? Is it a constant fraction, if so where does that number come from? Is it variable? If so, what does that number depend on?
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It depends on the temperature difference between the heat source and the heat sink; the higher the difference, the more efficient the conversion.
P.S. Ever heard of google?
Re:Thermodynamics (Score:5, Insightful)
P.S. Ever heard of google?
Please, it's a fairly esoteric piece of knowledge and this is as good a forum to ask it in as any. A bit of civility wouldn't kill you.
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Third law? I thought it was the second law of thermodynamics that says that not all heat can be converted back into energy.
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At least it's easier than constantly muttering block transfer computations into charged vacuum emboitments to hold back the inevitable heat death of the universe.
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How much energy can you actually reclaim from a given amount of heat? Is it a constant fraction, if so where does that number come from?
http://en.wikipedia.org/wiki/Carnot_cycle [wikipedia.org]
For each unit of heat energy, the maximum amount of work (useful energy extracted) is (1 - Tc/Th), where Tc and Th are the temperatures of the cold and hot side of the process.
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I'm sure somebody will come by in a few minutes to prove me wrong about everything I said.
"In this house, young lady... (Score:3, Informative)
That would be the second law, that would be broken if you could recover all the heat. The third law is a bit more obscure and basically means that the first two laws apply to everything.
The amount you can recover varies according to the efficiency of the device you use to recover it, and depends completely on the details of your setup. Obviously no device is 100% efficient (that's the second law again), so you will never be able to recover all of the
Re:Thermodynamics (Score:5, Funny)
That's the 2nd law, not 3rd.
1st law - You can't win.
2nd law - You can't even tie.
3rd law - You can't get out of the game.
Re:Thermodynamics (Score:4, Interesting)
As other posters have mentioned the physical limit you're concerned with is the Carnot efficiency.
One view of things not yet mentioned by posters is that energy is not what matters but exergy -- the capacity to do work. A bathtub full of lukewarm water contains a great deal of energy, but little exergy. In general, electrical and mechanical energy has a lot of exergy; thermal energy is as low-exergy as you can get, especially at low temperatures.
Note that the above is really just a rephrasing of the idea of entropy.
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Another point not mentioned is the economics of the situation.
Inherently the home device is going to raise the temperature of the appliance.
Higher temp appliance means it wears out faster.
Wears out faster means lots of energy spent on replacement.
So, at first glance, what has been designed is a way to save cents of electricity at a cost of dollars of repair work.
I don't think the car makers will like replacing an alternator with thermoelectrics, because they are immensely big and heavy for the power require
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It's a constant fraction depending on the temperature difference between the heat source and heat sink. (Plus, many factors that come into play in real system.) This figure comes from thermodynamics.
Is "Waste" Heat Really Free Energy? (Score:2)
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It's not "wasted" energy until we refrain from harnessing it. It's not free since we paid for it (by using the product that creates heat as a by-product).
What this is like, is the "5-second rule". This is scooping up perfectly edible M&Ms off the floor before they rot or the dog gets to it. This heat that is a by-product of reaction is still energy, so it's great that we have a way to pick it up and use it before it dissipates.
In the end, since we still want to eat M&Ms, we can reduce the overall nu
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You shouldn't be letting your dog eat any M&Ms at all. Chocolate is poisonous to dogs.
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There's no free lunch unless the food was going into the dumpster anyway. Practical engines throw away tons of heat. Heck, that's what your radiator is explicitly for. So since heat is leaking out of your engine at a prodigious rate anyway, you might as well use that flow to power another heat engine (a thermocouple in this case, I guess).
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If you're taking heat away before said heat moves the piston down, then yes, you're reducing the efficiency, and therefore power output.
If you're taking heat out of the upper radiator hose, or the exhaust pipe, both of which are just dumped out to the atmosphere, anyway, then it really is waste heat, and you're not reducing the efficiency of anything.
Recover enough heat, and you might be able to do with a smaller radiator and cooling fan, though, which, while it wouldn't increase the efficiency of the engin
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Yes.
There's a post above about the carnot cycle which is theoretically the most efficient engine for turning heat into useful energy. The carnot cycle efficiency is equal to 1-Tc/Th
Basically, the hotter your furnace and the colder your exhaust, the more efficient your system is. So if you have some powerplant's waste heat, it's not useful to you unless you have some reservoir of cold to dump that heat into while running your cycle. Obviously, it is more efficient to apply that cold reservoir to the original
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> cars have radiators for a reason. simply downsize/cover the radiator and the
> waste heat increases to a usable level.
Cars have thermostats for a reason, too. It's so you don't have to cover the radiator to get the engine temp up. ;)
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So, you're going to cripple a 35 kW heat engine to make a 4 W heat engine more efficient?
Wow (Score:2)
Power gain or loss? (Score:2)
How much energy is produced? I'd imagine not a lot. How much does it weigh? Does it cost more in fuel to lug these around than they can produce? You'd need one at the exhaust, one at the engine, one at the brakes..
Is this another deal where I spend $1000 and get 5w/hour?
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Devices like these are usually silicon wafers.
They will weigh less than your alternator.
And you'll only need one. Probably connected to your coolant line before the radiator to get it good and hot.
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I'm not familiar with the specific technology here, but most of these heat-recapture systems are Peltier systems. Compared to their power output, for something the size of a car, they're fairly light. Some of them are cheap enough to make -- they're what runs solid-state cooler chests -- but I'm only really familiar with research models (which are hard to price).
one acronym (Score:2)
$75 for an ipod charger? (Score:2, Funny)
Using "waste" sure is expensive...
Saw research into much larger scale uses of this (Score:2, Interesting)
I was visiting Illinois State University's physics department because I am planning on attending this fall. They were working on a material along these lines with a fairly high efficiency rate but they were just starting actually trying to make small amounts of the material.
Their intended use of the material would be in steel foundries, etc. where millions of dollars are spent on power and even something not very efficient could save a ton of money.
From what I gathered talking to the professor there the sa
Prior Art (Score:2)
Cooking [wikihow.com] on your car's engine.
Wall warts to charge my cell phone! (Score:4, Funny)
I wanna use my huge bank of toasty little wall warts to charge my cell phone. If I can do that the lazy little power-sucking tribbles might finally justify their existence.
Not news, not new technology! (Score:5, Informative)
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they're not very efficient at all, they don't last forever, and they're not particularly cheap
So... like an internal combustion engine, then?
Thermoelectric Efficiency? (Score:2)
How %efficient are these thermoelectric devices in outputting electric power W from the power W extracted by cooling the wastefully hot devices? And how much power does it take to manufacture one of these thermoelectric devices?
Cosmic microwave background radiation (Score:4, Funny)
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Let me assure you that in grammatical application it does nothing of the kind.
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You already have to use a radiator to get rid of the heat so you might as well do something useful with it.
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