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Body Heat Energy Generation
BuzzSkyline writes "Researchers in Belgium have developed devices to harvest the waste heat our bodies throw off in order to convert it to electricity to run devices such as a wristband blood oxygen sensor and an electrocardiogram shirt. As a side benefit, the power sources help cool you down and keep you looking cool, all while running sundry micropower devices. In fact, the researchers mention that the energy harvesting head band works so well that it can get uncomfortably cold. In that case, they say, 'This problem is solved in exactly the same way as someone solves it on the body level in cold weather: a headgear should be worn on top of the system to limit the heat flow and make it comfortable.' But it would be such a shame to cover up the golden heat-harvesting headband with a hat."
You're wasting the real potential of this thing. I live in an area that gets hot as hell in the summer. If it really does get "uncomfortably cold," I'd pay good money for a whole suit made of the stuff.
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It feels cold because it's sucking heat out and using it. So it's constantly leaching heat out. Hence it would feel cold. Simple, really.
Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
As a side benefit, the power sources help cool you down
Typically if you take something that's trying to dump waste heat, and install something that recovers power from that heat, it creates an insulating effect, reducing the cooling the object was receiving. Heat can't be turned directly into energy, only difference in heat. Adding a heat reclamation system doesn't help cool something down because the power it's getting is from the temperature difference, not the heat itself. Instead it takes power from the temperature gradient, and as such reduces the temperature gradient, thus reducing cooling efficiency.
I work for the Department of Redundancy Department.
I was going to just mod you down, but the summary at least never said anything about lowering any part of the device below ambient. It said that the headband will "feel cold". Touch a piece of wood at room temperature. It will sometimes "feel" warm. Do the same thing with a piece of steel. It will "feel" cold. This is true even if both are at the exact same temperature. Heat conduction
The kids section of my local science museum even has hand-shaped pieces of different materials to demonstrate the effect.
The headband is at ambiant temperature, but your body is much warmer. Heat flow from your body to the headband and leaves a cold sensation on your skin. The material of the headband applied to the body is probably a good conductor of heat ; it's like with a piece of metal that feels cold to the touch and a piece of wood that doesn't while both are at room temperature.
That only works if the air temp is lower than 98.6. This sort of thing works by harnessing the difference in energy between the "hot" side and the "cold" side. Sure, it would work well at room-temperature, but who needs cooling at room-temp? About the only time you really need cooling when the air is significantly below normal body temperature outside is when you've got a fever, or are heavily exerting yourself. I definitely could get behind a headband that powers an mp3 player when I'm on a jog. It could have military applications, but it would be fairly limited. When it's 120 degrees in Iraq, this thing wouldn't work even if the soldier was running a marathon while dragging a broken down Humvee.
I live in Canada... I need all of my body heat as it is.
AccountKiller
http://en.wikipedia.org/wiki/Battery_(electricity)#Rechargeable_battery_chemistries
I'd love to know where you get 5 kWh from an iPhone battery. Li-Ion batteries have an energy density of 128 Wh/kg, so your iPhone battery must weigh 39 kg.
Granted, a 5 kWh Li-Ion battery will cost a fortune, so for something of that capacity, you're more likely to use a lead-acid battery of car/alarm/emergency light fame. That battery would weigh 129 kg. My brother-in-law has an iPhone; I'll ask him if it came with a dolly for the battery.
Now, it would make more sense if that was a 5 Wh battery; then we're talking about 39 grams, which is probably a bit easier to carry around. And your charging cost is down to 0.005p, but will likely be a good deal higher due to energy loss.
It's not sucking heat out, that would actually require extra energy input. It's not a pump, it's more like a water wheel.
But my question has been answered. It doesn't get below ambient temperature. We just don't feel ambient temperature as cold as it actually is, because air is a pretty good insulator.
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Wouldn't it be extremely marketable? Especially for the military with troops in hot places and with bulky body armor and probably all types of personal electronic equipment to keep charged?
This also defies the laws of thermodynamics. Allow me to explain:
1. In Iraq, the surroundings are hotter than the human body. Therefore, it is impossible to harvest energy from human waste heat because heat is flowing to the human, not away from it.
2. The temperature gradient between a humans body and it's surroundings is not large enough to generate significant amounts of electricity. If it was, internal combustion engines would be a hell of a lot more efficient than they are today.
3. If the temperature gradient between a human body and it's surroundings were large enough to generate significant amounts of electricity, you might want that energy to keep warm!
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
Though perhaps they won't need massive amounts of force to subdue humanity; from what I've seen, most people would choose the blue pill.
I've long believed that the physical reality we live in, being entirely a product of energy and thus little more than an illusion, the idea of matter and as such is inherently linked to consciousness. . , that all things in our reality can be observed as and understood to be metaphors for systems and conflicts we are experiencing in our conscious awareness.
-You have to plug humans into the Matrix at the start of their lives when kids are most inquisitive. Red Smarties are the most popular color, and the battle over Blue Smarties rages on. . !
Humans naturally try to reject the Matrix. "Entire crops were lost."
Neat, huh?
-FL
As for me, electricity costs are getting so high that a human sized hamster wheel attached to a basic generator coil looks really attractive right now.
Of course, the problems involved in acquiring and caring for a human sized hamster tend to outweigh the benefits.
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