
Thermoelectric Stoves: Ditch the Solar Panels? - Shared404
https://solar.lowtechmagazine.com/2020/05/thermoelectric-stoves-ditch-the-solar-panels.html
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yodelshady
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.

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m463
I think the article is worth the click, even if just for the soviet history.

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ChuckMcM
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-...](https://gazettereview.com/2016/06/powerpot-after-shark-tank-update-
now/)

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dredmorbius
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
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.

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

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millstone
Wood pellets are efficient, produce low pollution, and are one of the most
renewable fuels.

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dr_dshiv
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/S136403212...](https://www.sciencedirect.com/science/article/pii/S1364032120305669?casa_token=Lx5In3Xs1ScAAAAA:tw9ybNRqT3vZDtz_FI698oaBCDw-
KwLSuRvpoOvd_FWNZHi7haZHm9ZWjmYs8ytXAZDsj3p85Ic#sec5)

~~~
millstone
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.

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jeffbee
Recently:
[https://news.ycombinator.com/item?id=23348578](https://news.ycombinator.com/item?id=23348578)

~~~
Shared404
Sorry about that, I missed that thread.

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yellowapple
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.

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gpm
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).

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vitiral
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.

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rudolph9
Combined heat and power is fairly common in Europe
[https://en.wikipedia.org/wiki/Cogeneration](https://en.wikipedia.org/wiki/Cogeneration)

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sneak
[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.

~~~
lapinot
There's no debating that inhaling (any kind of) smoke is pretty bad. For the
rest of the article i'm gonna have to call bs.

1\. Outside air: We're not talking about cities. Burning stuff in dense
habitation zones is stupid. Sibling comments have hinted at atmospheric
inversion, which is a localized and largely exceptional effect. Also: it's not
too hard to take that into account and have a fire at nights and during
winter, periods during which people aren't too much out.

2\. Inside air: Any well designed and well tended fire-place (and its
associated well-dried wood) generates no smoke in the room. If it does you're
doing in wrong. If you intend to heat your home you should go for a closed
stove, if you intend to cook you should have a well ventilated open-furnace
and learn to use it right. Source: my childhood home at the country-side
heated exclusively (hot water was electric) with a stove in the living room
and an open furnace in the kitchen.

3\. Deforestation: we have too much wood. Apart from rain-forests, at
"occidental latitudes" most forests are growing (at least i know for sure in
france). In my country-side some farmer neighbor always had spare wood to
sell, from cutting trees around their fields (of course you have to do it
intelligently: not cut the younger ones, etc). A farm of a half a dozen
hectares can be self-sufficient in heating wood (source: neighbors).

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dredmorbius
"Too much wood" is only an artefact of recent industrialised use of coal, oil,
and nuclear energy. Through the 19th century, deforestation was rampant in
Europe and North America, and remains a problem throughout much the rest of
the world. Largely driven my small-scale fuelwood use.

Industrial-scale charcoal-fired bronze, iron, and glass-smelting use
prodigious amounts of wood fuel, multiples of the yielded product mass.

~~~
lapinot
Aren't you contradicting yourself with the industrial uses point? I don't have
any strong refs but my understanding is that 19th c. deforestation was driven
by growing population, which isn't a problem in europe for much of the
foreseeable future. Btw there have been big advances in forest management and
forest-compatible agriculture (agroforestry and intercropping in general).

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dredmorbius
Deforestation well-predated the 19th century, and increased at rates greater
than population growth, strongly driven by novel or expanded uses.

See Vaclav Smil, _Energy and Civilization_ , on energy use generally. Jed O.
Kaplan; Kristen M. Krumhardt; Niklaus Zimmermann, "The prehistoric and
preindustrial deforestation of Europe' (10.1016/j.quascirev.2009.09.028
[http://gen.lib.rus.ec/scimag/10.1016%2Fj.quascirev.2009.09.0...](http://gen.lib.rus.ec/scimag/10.1016%2Fj.quascirev.2009.09.028))
gives an overview of trends and some uses.

Wikipedia has a generally accurate though poorly sourced article:
[https://en.wikipedia.org/wiki/History_of_the_forest_in_Centr...](https://en.wikipedia.org/wiki/History_of_the_forest_in_Central_Europe)

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lapinot
Thanks, i'll look into that.

