How to Charge Your Cellphone Using Wasted Heat

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."

Comments

I charge my cellphone while riding my Carnot cycle

[thomasdz]

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

Re:Wish I could harvest the power from my farts...

[d474]

Did you customize that sig to your comment, or should you go see a doctor about your explosive flatulence problem?

Sipping From a Firehose

[lobiusmoop]

Given that the average American consumes 13,500KWh per year, 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.

Re:Sipping From a Firehose

[Toonol]

It's vastly more efficient, and probably less expensive, to redesign the Dryer/Air Conditioner/whatever to waste less heat in the first place. So I'm not really disagreeing with you, but I feel that it's a bit more of a feel good effort than an actual relevant solution.

Re:Sipping From a Firehose

[chromas]

I used to have neighbors who would leave their air conditioners running all day, then, when they came home, they'd let the doors hang open for a while to let some warm in. Less stupid people could help, too.

Re:Sipping From a Firehose

[Rich0]

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

[DirtyUncleRon69]

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

[lobiusmoop]

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.

At last!

[goombah99]

finally someone invents a use for the formerly useless lego mindstorms thermal sensor. Use it to let your mindstorms bot find a recharging stations

Re:BWM?

[Anonymusing]

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 makes awesome cars

[Hognoxious]

I prefer Adui. You can't beat their Quartto transmission on a wet road.

Re:laptop heat? can that be used to charge it self

[zindorsky]

No. See the laws of thermodynamics.

Re:Thermodynamics

[AnotherBlackHat]

Obviously you can reclaim some energy from heat, but you can't reclaim it all, as that would break the 3rd law of thermodynamics.

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:laptop heat? can that be used to charge it self

[Linker3000]

That heat is traditionally used for roasting nuts

Re:Thermodynamics

[jabithew]

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.

Not news, not new technology!

[kheldan]

Peltier Junctions are really old news, they're not very efficient at all, they don't last forever, and they're not particularly cheap. TFA doesn't have anything new to say or any links that have anything new to say. Mod the entire post down to -1, Useless post and move on.