4 ms·

Huge losses at every stage, I guess. A good chunk of the heat is going to go right up the chimney, then most of the heat that doesn't escape is going to directl

by makomk 6y ago

Huge losses at every stage, I guess. A good chunk of the heat is going to go right up the chimney, then most of the heat that doesn't escape is going to directly heat the room the stove is in without going through the thermoelectric elements, and then only a tiny fraction of the tiny fraction that passes through them is going to get converted to electricity. What might be better is something more like a steam engine, except without the complicated maintenance and operation requirements and the annoying tendency to explode if not carefully maintained. Sadly no-one seems to have been able to design such a device.

vkou 6y ago
> Sadly no-one seems to have been able to design such a device. Why not a Stirling engine?
- namibj 6y ago
  https://www.microgen-engine.com/ https://www.microgen-engine.com/ seems to be a commercial source, and https://www.kickstarter.com/projects/672465444/low-cost-sterling-engine/ https://www.kickstarter.com/projects/672465444/low-cost-ster... was a (failed?) attempt at developing a cheap 1kW generator. The more recent remains are in this blog: http://volodesigns-sterlingproject.blogspot.com/ http://volodesigns-sterlingproject.blogspot.com/ It looks like the Kickstarter turned into https://seftonmotors.com/ https://seftonmotors.com/ , which are about 2000$ for a 1.2kW (full temp, pressurized) engine.
  - makomk 6y ago
    Yeah, that's the problem - all the Sterling engine solutions end up as expensive, exotic, low production natural gas powered devices. Which means that you need a supply of natural gas, and at that point you have other generation options. There was a slightly lower-power, but much more compact and finished Australian product along the same lines a decade or so ago called the WhisperGen which was intended to replace a hot water and heating boiler. They ended up going out of business unfortunately.
    - namibj 6y ago
      Not sure where you're getting the nat-gas-fired idea from. The more-commercial link I provided seems available as a micro-CHP setup, with a wood-pellet furnace. The Melvin Package from Selfton Motors has a combined propane/wood fire box, but the Melvin engine itself is a separate part, allowing use of a custom heat source. I'm not sure though why you want to burn wood on that scale. It's really expensive to properly filter the exhaust from a wood stove, and economy of scale doesn't hit in the kW range. I mean, yes, if you're in the middle of nowhere, sure, but I'd claim that an install cost of 3~4$/W(electric) for the Melvin Package, including shipping (even to a potentially-remote location, only 100kg for the largest piece allows transport with e.g. a paramotor or two humans, with additional trips for the cooling jacket/firebox/vents/piping) is acceptable for a reliable wood-fueled electricity source.
akira2501 6y ago
> A good chunk of the heat is going to go right up the chimney It's probably not much.. but I imagine you could boost the efficiency by lining the chimney with copper tube and running water through it, using the waste heat there to heat this water. Then use your TEG as a heat-exchanger between that loop and another loop connected to your "domestic water heater" or other cold water supply.

by makomk 6y ago

vkou 6y ago

> Sadly no-one seems to have been able to design such a device. Why not a Stirling engine?

namibj 6y ago
https://www.microgen-engine.com/ https://www.microgen-engine.com/ seems to be a commercial source, and https://www.kickstarter.com/projects/672465444/low-cost-sterling-engine/ https://www.kickstarter.com/projects/672465444/low-cost-ster... was a (failed?) attempt at developing a cheap 1kW generator. The more recent remains are in this blog: http://volodesigns-sterlingproject.blogspot.com/ http://volodesigns-sterlingproject.blogspot.com/ It looks like the Kickstarter turned into https://seftonmotors.com/ https://seftonmotors.com/ , which are about 2000$ for a 1.2kW (full temp, pressurized) engine.
- makomk 6y ago
  Yeah, that's the problem - all the Sterling engine solutions end up as expensive, exotic, low production natural gas powered devices. Which means that you need a supply of natural gas, and at that point you have other generation options. There was a slightly lower-power, but much more compact and finished Australian product along the same lines a decade or so ago called the WhisperGen which was intended to replace a hot water and heating boiler. They ended up going out of business unfortunately.
  - namibj 6y ago
    Not sure where you're getting the nat-gas-fired idea from. The more-commercial link I provided seems available as a micro-CHP setup, with a wood-pellet furnace. The Melvin Package from Selfton Motors has a combined propane/wood fire box, but the Melvin engine itself is a separate part, allowing use of a custom heat source. I'm not sure though why you want to burn wood on that scale. It's really expensive to properly filter the exhaust from a wood stove, and economy of scale doesn't hit in the kW range. I mean, yes, if you're in the middle of nowhere, sure, but I'd claim that an install cost of 3~4$/W(electric) for the Melvin Package, including shipping (even to a potentially-remote location, only 100kg for the largest piece allows transport with e.g. a paramotor or two humans, with additional trips for the cooling jacket/firebox/vents/piping) is acceptable for a reliable wood-fueled electricity source.

akira2501 6y ago

> A good chunk of the heat is going to go right up the chimney It's probably not much.. but I imagine you could boost the efficiency by lining the chimney with copper tube and running water through it, using the waste heat there to heat this water. Then use your TEG as a heat-exchanger between that loop and another loop connected to your "domestic water heater" or other cold water supply.