6 ms·

Thermoelectric Stoves: Ditch the Solar Panels?

34 points by Shared404 6y ago

jacinabox 6y ago
Wood burning contributes unnecessarily to deforestation and emits a lot of air pollution, things people used to think were no bueno.
- millstone 6y ago
  Wood pellets are efficient, produce low pollution, and are one of the most renewable fuels.
  - dr_dshiv 6y ago
    Mind blown. Yet, Life Cycle Analyses show conflicting results. Here is a recent review. Would be very good to know whether this has potential as a future biofuel. https://www.sciencedirect.com/science/article/pii/S1364032120305669?casa_token=Lx5In3Xs1ScAAAAA:tw9ybNRqT3vZDtz_FI698oaBCDw-KwLSuRvpoOvd_FWNZHi7haZHm9ZWjmYs8ytXAZDsj3p85Ic#sec5 https://www.sciencedirect.com/science/article/pii/S136403212...
    - millstone 6y ago
      In our best future we grow trees and log them for construction, storing their carbon. We process the waste branches, bark, etc. into wood pellets which get burned, displacing the use of fossil fuels. There's very real questions about how wood pellets are sourced, but moving from burning ancient fossils to burning recent trees has to be directionally correct, part of the solution.
  - Tyr42 6y ago
    Wait that's not just something seablock and factorio made up?
  - 7952 6y ago
    Lower pollution compared to burning logs perhaps. But still much higher than a modern oil or gas heating system.
- magicalhippo 6y ago
  My cabin, which was put up by my grand parents, has a picture of the view back in the 50s. When comparing it to the view outside today it's easy to see the treeline has moved up hundreds of meters in altitude. Mountains that were bare are now part of the forest. Not saying we should promote wood burning, but I'm not tossing out the old wooden stove.
  - m463 6y ago
    I thought it was thinner air that caused the treeline, is it temperature? or is it air, which just has more CO2?
    - throwaway5752 6y ago
      It's temperature. Which, of course, is because the air has more CO2.
    - Ma8ee 6y ago
      Temperature. The tree line moves down the further north you go.
    - magicalhippo 6y ago
      There are primarily two factors are driving it. People and especially farmers have changed how they use the land. There are much less animals grazing, thus not keeping forests in check. As mentioned temperatures have also increased, which allows trees to grow at an higher altitude than before. Here's a relatively recent news article about this[1], including a couple of images of the same place 50 years apart showing the progress. [1]: https://www.nrk.no/innlandet/norges-hoyestvoksende-tre-skaper-bekymring-blant-forskere-1.14653798 https://www.nrk.no/innlandet/norges-hoyestvoksende-tre-skape...
  - deleted 6y ago
    [deleted]
- dredmorbius 6y ago
  And yet it remains in use in many places. As the article notes, a properly-designed stove with forced draft and postcombustion airflow could reduce both fuel use and pollution. In theory. I'd like to see this actually tested.
gpm 6y ago
Thermoelectrics generate power by allowing heat to flow from a hot area to a cold area. Almost certainly you would be better off efficiency-wise by putting insulation in place of the thermoelectric element and generating electricity in a central steam power plant (fueled with the fuel you save via the insulation).
yodelshady 6y ago
Saving you a click - "it's efficient if you count waste heat as useful". As a rule of thumb, a good PV panel and a good thermal engine will give you similar efficiencies - a little under 20%, more if you want to spend lots, but really very tricky to exceed mid-30s. A thermoelectric generator, quoted as "1/3rd as efficient as PV" - sounds about right, so maybe 6%. PV panels consume land. A wood-fired generator as suggested would need at least 10x the land to grow the trees for the same energy input, even forgetting the difference in efficiency. Probably closer to 100x. Oh, and PV works in literal deserts, where land is cheap, because it's useless to grow food or as a reserve, so you're sacrificing nothing! The closest practical variant of this is district heating with a regular fossil- or nuclear- turbine generator. IIRC, a few towns in Russia have genuinely too cheap to meter heat because of this.
- m463 6y ago
  I think the article is worth the click, even if just for the soviet history.
- vkou 6y ago
  > IIRC, a few towns in Russia have genuinely too cheap to meter heat because of this. There's an engineering reason for it, as well, that has nothing to do with economics. A lot of the apartment blocks built in Russia during the later communist years were built from prefabs - essentially, entire 'rooms' would arrive on trucks from a factory, and would get snapped together like lego bricks. The plumbing was pre-installed in these rooms - specifically, it would be pre-wired into the solid-concrete walls, at the point of manufacture - so that construction workers did not have to actually do any plumbing at the time of assembly. This is a great system, because you can put a building together very quickly. It does have a few drawbacks, though. Russian winters are cold. Really, really, really cold. So cold, in fact, that during winter, hot water plumbed through the buildings is the only thing that keeps their occupants from freezing to death. Most of these buildings don't have any other source of heating. Of course, if hot water ever stops getting plumbed through your building (Because of, say, a ruptured pipe, a problem at the central heating plant, etc), then, in a matter of days, every single pipe in your apartment block will freeze solid, and explode. This would be bad enough in a 'normal' building, but it is made worse, because the pipes aren't even accessible for maintenance - they are buried deep within the walls of the concrete prefabs.
ChuckMcM 6y ago
I chuckled at this: "With appropriate stove design, the heat from electricity conversion can also be re-used for cooking or domestic water heating." Except that thermodynamics gets in the way :-). The heat that is converted into electricity is, electricity. So it is no longer part of heat available for heating. If you did have 100% efficient thermoelectrics they would be pretty neat since you could put as much wood or fuel into your stove as you wanted and the surface of the stove wouldn't change temperature at all, but there would be electricity available! That said, using thermoelectric conversion to charge your cell phone when camping[1] (and using the fire for toasting marshmellows) is a win :-). But it isn't going to replace solar any time soon sadly. [1] https://gazettereview.com/2016/06/powerpot-after-shark-tank-update-now/ https://gazettereview.com/2016/06/powerpot-after-shark-tank-...
- dredmorbius 6y ago
  Waste heat is heat. So long as it is above ambient temperatures, it i useful for something. Feeding low-grade heat into a stratified water thermal storage system is particularly effective. So long as the water is allowed to stratify by temperature, cold water will settle to the bottom and can be heated by any warmer material. In practice, outflow for (re)heating is at the bottom of the tank, outflow for use at the top, and inflow is through a perforated vertical pipe allowing introduction at level of thermal equilibrium.
  - ChuckMcM 6y ago
    I don't disagree with you, I was just chuckling at the suggestion that heat that created the electricity could be "re-used". As you note, waste heat is the heat that is left over after you've used some of it. The part you used is no longer heat (it may be electricity it may be kinetic or potential energy, it might even be chemical energy, but it isn't "heat" any more). One of the coolest uses of ambient heat I've seen so far has been the new heat pump water heaters, they cool your garage as they pull latent heat into the water inside the tank. The trick though is that your garage gets cooler :-) (i.e. the heat has gone elsewhere). There are also some pretty cool thermo-electric solutions where you stick a device on the indoors side of a window to the out of doors. It uses the delta between the window glass temperature and the indoor temperature to power a simple sensor. Not as useful on double glazed windows but awesome for single pane ones.
sneak 6y ago
https://samharris.org/the-fireplace-delusion/ https://samharris.org/the-fireplace-delusion/ You should not burn wood at all. Woodsmoke is truly terrible pollution that harms you and everyone around you for most of a mile radius. It smells really nice but is utterly damaging.
- 01100011 6y ago
  That is an informative article that leaves me wanting to disregard it because of the condescending tone. I guess I prefer facts separate from the moralizing. I wonder how modern pellet stoves with more complete combustion compare to traditional wood fires?
  - strogonoff 6y ago
    In addition to describing old methods of burning wood, when speaking about its health effects this article completely ignores the weather factor. Even with proper chimney construction, atmospheric pressure and presence or absence of inversion can cause smoke to hover at the ground for days—or quickly take it to high altitudes and disperse. I am not sure whether the research he mentions controlled for this factor. In particular, quotes like this: > It might be the clearest day of the year, but burn a sufficient quantity of wood and the air in the vicinity of your home will resemble a bad day in Beijing. strongly hint at atmospheric inversion, frequent in some areas and rare in others. (Also, “sufficient quantity of wood” makes the point completely meaningless, but that aside…) IMO recommending for or against wood burning should take into account typical weather patterns of a particular area, and ideally there should be a way to notify people when atmospheric conditions are not right for this. I agree that Sam Harris has a frustrating tendency to moralize, but I still subscribe to his podcast. There are good points raised in most discussions, if not by him then by his guest. Strong opinions is a double-edged sword.
    - 7952 6y ago
      In my country people leave their wood burner running all winter regardless of the weather. People are never going to turn it off just because of weather conditions. And there is moralising on the other side of the argument, it is just less explicit. The old fashioned "natural" manliness of chopping and burning wood is definitely considered virtuous by a lot of people. Maybe this is restricted to middle class though.
jeffbee 6y ago
Recently: https://news.ycombinator.com/item?id=23348578 https://news.ycombinator.com/item?id=23348578
- Shared404 6y ago
  Sorry about that, I missed that thread.
  - yellowapple 6y ago
    Eh, I'd say you're alright. Usually when people post links to prior discussions, it's specifically to make those prior discussions available to the current discussion and provide additional context. This doesn't seem to be an exception; the previous discussion was more than 3 months ago, long past the point when anyone would still be participating in it, so a new post with a new discussion is perfectly appropriate.
vitiral 6y ago
Recommend organic rankin or Sterling cycle engines over thermoelectric generator. I believe households in Sweden actually have heaters that use methane and also produce electricity at reasonably high efficiency.
rudolph9 6y ago
Combined heat and power is fairly common in Europe https://en.wikipedia.org/wiki/Cogeneration https://en.wikipedia.org/wiki/Cogeneration

34 points by Shared404 6y ago

Wood burning contributes unnecessarily to deforestation and emits a lot of air pollution, things people used to think were no bueno.

millstone 6y ago
Wood pellets are efficient, produce low pollution, and are one of the most renewable fuels.
- dr_dshiv 6y ago
  Mind blown. Yet, Life Cycle Analyses show conflicting results. Here is a recent review. Would be very good to know whether this has potential as a future biofuel. https://www.sciencedirect.com/science/article/pii/S1364032120305669?casa_token=Lx5In3Xs1ScAAAAA:tw9ybNRqT3vZDtz_FI698oaBCDw-KwLSuRvpoOvd_FWNZHi7haZHm9ZWjmYs8ytXAZDsj3p85Ic#sec5 https://www.sciencedirect.com/science/article/pii/S136403212...
  - millstone 6y ago
    In our best future we grow trees and log them for construction, storing their carbon. We process the waste branches, bark, etc. into wood pellets which get burned, displacing the use of fossil fuels. There's very real questions about how wood pellets are sourced, but moving from burning ancient fossils to burning recent trees has to be directionally correct, part of the solution.
- Tyr42 6y ago
  Wait that's not just something seablock and factorio made up?
- 7952 6y ago
  Lower pollution compared to burning logs perhaps. But still much higher than a modern oil or gas heating system.
magicalhippo 6y ago
My cabin, which was put up by my grand parents, has a picture of the view back in the 50s. When comparing it to the view outside today it's easy to see the treeline has moved up hundreds of meters in altitude. Mountains that were bare are now part of the forest. Not saying we should promote wood burning, but I'm not tossing out the old wooden stove.
- m463 6y ago
  I thought it was thinner air that caused the treeline, is it temperature? or is it air, which just has more CO2?
  - throwaway5752 6y ago
    It's temperature. Which, of course, is because the air has more CO2.
  - Ma8ee 6y ago
    Temperature. The tree line moves down the further north you go.
  - magicalhippo 6y ago
    There are primarily two factors are driving it. People and especially farmers have changed how they use the land. There are much less animals grazing, thus not keeping forests in check. As mentioned temperatures have also increased, which allows trees to grow at an higher altitude than before. Here's a relatively recent news article about this[1], including a couple of images of the same place 50 years apart showing the progress. [1]: https://www.nrk.no/innlandet/norges-hoyestvoksende-tre-skaper-bekymring-blant-forskere-1.14653798 https://www.nrk.no/innlandet/norges-hoyestvoksende-tre-skape...
- deleted 6y ago
  [deleted]
dredmorbius 6y ago
And yet it remains in use in many places. As the article notes, a properly-designed stove with forced draft and postcombustion airflow could reduce both fuel use and pollution. In theory. I'd like to see this actually tested.

gpm 6y ago

Thermoelectrics generate power by allowing heat to flow from a hot area to a cold area. Almost certainly you would be better off efficiency-wise by putting insulation in place of the thermoelectric element and generating electricity in a central steam power plant (fueled with the fuel you save via the insulation).

yodelshady 6y ago

Saving you a click - "it's efficient if you count waste heat as useful". As a rule of thumb, a good PV panel and a good thermal engine will give you similar efficiencies - a little under 20%, more if you want to spend lots, but really very tricky to exceed mid-30s. A thermoelectric generator, quoted as "1/3rd as efficient as PV" - sounds about right, so maybe 6%. PV panels consume land. A wood-fired generator as suggested would need at least 10x the land to grow the trees for the same energy input, even forgetting the difference in efficiency. Probably closer to 100x. Oh, and PV works in literal deserts, where land is cheap, because it's useless to grow food or as a reserve, so you're sacrificing nothing! The closest practical variant of this is district heating with a regular fossil- or nuclear- turbine generator. IIRC, a few towns in Russia have genuinely too cheap to meter heat because of this.

m463 6y ago
I think the article is worth the click, even if just for the soviet history.
vkou 6y ago
> IIRC, a few towns in Russia have genuinely too cheap to meter heat because of this. There's an engineering reason for it, as well, that has nothing to do with economics. A lot of the apartment blocks built in Russia during the later communist years were built from prefabs - essentially, entire 'rooms' would arrive on trucks from a factory, and would get snapped together like lego bricks. The plumbing was pre-installed in these rooms - specifically, it would be pre-wired into the solid-concrete walls, at the point of manufacture - so that construction workers did not have to actually do any plumbing at the time of assembly. This is a great system, because you can put a building together very quickly. It does have a few drawbacks, though. Russian winters are cold. Really, really, really cold. So cold, in fact, that during winter, hot water plumbed through the buildings is the only thing that keeps their occupants from freezing to death. Most of these buildings don't have any other source of heating. Of course, if hot water ever stops getting plumbed through your building (Because of, say, a ruptured pipe, a problem at the central heating plant, etc), then, in a matter of days, every single pipe in your apartment block will freeze solid, and explode. This would be bad enough in a 'normal' building, but it is made worse, because the pipes aren't even accessible for maintenance - they are buried deep within the walls of the concrete prefabs.

ChuckMcM 6y ago

I chuckled at this: "With appropriate stove design, the heat from electricity conversion can also be re-used for cooking or domestic water heating." Except that thermodynamics gets in the way :-). The heat that is converted into electricity is, electricity. So it is no longer part of heat available for heating. If you did have 100% efficient thermoelectrics they would be pretty neat since you could put as much wood or fuel into your stove as you wanted and the surface of the stove wouldn't change temperature at all, but there would be electricity available! That said, using thermoelectric conversion to charge your cell phone when camping[1] (and using the fire for toasting marshmellows) is a win :-). But it isn't going to replace solar any time soon sadly. [1] https://gazettereview.com/2016/06/powerpot-after-shark-tank-update-now/ https://gazettereview.com/2016/06/powerpot-after-shark-tank-...

dredmorbius 6y ago
Waste heat is heat. So long as it is above ambient temperatures, it i useful for something. Feeding low-grade heat into a stratified water thermal storage system is particularly effective. So long as the water is allowed to stratify by temperature, cold water will settle to the bottom and can be heated by any warmer material. In practice, outflow for (re)heating is at the bottom of the tank, outflow for use at the top, and inflow is through a perforated vertical pipe allowing introduction at level of thermal equilibrium.
- ChuckMcM 6y ago
  I don't disagree with you, I was just chuckling at the suggestion that heat that created the electricity could be "re-used". As you note, waste heat is the heat that is left over after you've used some of it. The part you used is no longer heat (it may be electricity it may be kinetic or potential energy, it might even be chemical energy, but it isn't "heat" any more). One of the coolest uses of ambient heat I've seen so far has been the new heat pump water heaters, they cool your garage as they pull latent heat into the water inside the tank. The trick though is that your garage gets cooler :-) (i.e. the heat has gone elsewhere). There are also some pretty cool thermo-electric solutions where you stick a device on the indoors side of a window to the out of doors. It uses the delta between the window glass temperature and the indoor temperature to power a simple sensor. Not as useful on double glazed windows but awesome for single pane ones.

sneak 6y ago

https://samharris.org/the-fireplace-delusion/ https://samharris.org/the-fireplace-delusion/ You should not burn wood at all. Woodsmoke is truly terrible pollution that harms you and everyone around you for most of a mile radius. It smells really nice but is utterly damaging.

01100011 6y ago
That is an informative article that leaves me wanting to disregard it because of the condescending tone. I guess I prefer facts separate from the moralizing. I wonder how modern pellet stoves with more complete combustion compare to traditional wood fires?
- strogonoff 6y ago
  In addition to describing old methods of burning wood, when speaking about its health effects this article completely ignores the weather factor. Even with proper chimney construction, atmospheric pressure and presence or absence of inversion can cause smoke to hover at the ground for days—or quickly take it to high altitudes and disperse. I am not sure whether the research he mentions controlled for this factor. In particular, quotes like this: > It might be the clearest day of the year, but burn a sufficient quantity of wood and the air in the vicinity of your home will resemble a bad day in Beijing. strongly hint at atmospheric inversion, frequent in some areas and rare in others. (Also, “sufficient quantity of wood” makes the point completely meaningless, but that aside…) IMO recommending for or against wood burning should take into account typical weather patterns of a particular area, and ideally there should be a way to notify people when atmospheric conditions are not right for this. I agree that Sam Harris has a frustrating tendency to moralize, but I still subscribe to his podcast. There are good points raised in most discussions, if not by him then by his guest. Strong opinions is a double-edged sword.
  - 7952 6y ago
    In my country people leave their wood burner running all winter regardless of the weather. People are never going to turn it off just because of weather conditions. And there is moralising on the other side of the argument, it is just less explicit. The old fashioned "natural" manliness of chopping and burning wood is definitely considered virtuous by a lot of people. Maybe this is restricted to middle class though.

jeffbee 6y ago

Recently: https://news.ycombinator.com/item?id=23348578 https://news.ycombinator.com/item?id=23348578

Shared404 6y ago
Sorry about that, I missed that thread.
- yellowapple 6y ago
  Eh, I'd say you're alright. Usually when people post links to prior discussions, it's specifically to make those prior discussions available to the current discussion and provide additional context. This doesn't seem to be an exception; the previous discussion was more than 3 months ago, long past the point when anyone would still be participating in it, so a new post with a new discussion is perfectly appropriate.

vitiral 6y ago

Recommend organic rankin or Sterling cycle engines over thermoelectric generator. I believe households in Sweden actually have heaters that use methane and also produce electricity at reasonably high efficiency.

rudolph9 6y ago

Combined heat and power is fairly common in Europe https://en.wikipedia.org/wiki/Cogeneration https://en.wikipedia.org/wiki/Cogeneration