Using body heat as a power source

You've heard of geo-thermal energy, but what about homeo-thermal energy? I know I sure haven't, mostly because I just made up that word :)

Bad portmanteaus aside, what do you guys think of this concept? Running or charging things using the body heat you generate throughout the day and especially during the night.

I'm not sure how plausible it actually is, or how efficient it is, but I thought it'd be a nice project to start working on and wanted to know what you guys think of it. Is it worth-while? Too complicated? Not scientific enough? I'm interested in your feedback! :)

The SYNer2 years ago

Two good cycles for harvesting waste heat: Organic Rankine Cycle(ORC) and the Sterling Cycle. The ORC might be more efficient, but it is much more complicated. The sterling cycle combines low-temperature input, simplicity, diy-ability, and low cost.

In the case of of the ORC, mildly pressurised butane would be the best working fluid, because its boiling point is neither to low to risk hypothermia, or require high pressurisation, or to high to boil from body heat. You could sleep in an insulated chamber with forced-air ventilation. Waste heat would then be extracted from the heated air using a heat-exchanger. The ORC approach may be academically interesting, but good luck implementing it without a turbine. Rather good luck getting/making a turbine.

In the case of the Sterling cycle, get a thin slab of aluminium and a bunch of aluminium cans. Make a large number of Beta-type sterling engines and attach them to the slab using thermal glue. Hook up the sterlings to generators and you are done. Another, possibly cheaper, implementation would be to make a thin(20-30 cm) wooden box frame, cover in aluminium sheet(from aluminium ducts), make it air tight, and add some holes for the hot-cylinder of an alpha-type sterling engine. Maybe fill the box portion with steel wool or just add fins/pins to the inside of the aluminium sheet that will be in contact with your body.

Make sure you use a big...thick...warm...soft?... blanket. I cant imagine this bed would be all that comfortable, but I'm pretty sure it would work.

The SYNer The SYNer2 years ago

Paragraph 2, lines 2 and 3, "...to..." *too

Kiteman2 years ago