3 ms·

I don't know if this is right. We're talking about thermodynamic heaters, like Peltier elements, correct? Those need electricity to work and the question then b

I don't know if this is right. We're talking about thermodynamic heaters, like Peltier elements, correct? Those need electricity to work and the question then becomes: where does the electricity come from? Burning wood, if it can be done efficiently, and like the article says, is almost neutral in terms of carbon emissions because you're only realeasing carbon that is part of the atmospheric carbon cycle, circulating between the atmosphere and the biosphere. With a heat pump, if the electricity comes from burning fossil fuel then you're contributing to greenhouse gas emissions (all those carbon gasses are released in a much higher rate than they were stored and, more importantly, than what the environment can keep up with). If the electricity comes from renewable sources, then it's a real saving, but how probable is that right now? If you can burn wood at 80-90% efficiency, as the article claims, then that's a net gain right now. Personally I also don't like the reliance on a complicated mechanism that can't be easily made by hand. I don't like that because it means the technology is harder to adopt. I'm talking about heat pumps. By the sound of it an "oven stove" is much easier to make and maintain, if they had them back in the middle ages. So they can be used by many more people for whom the price of electricity is higher than the price of scrap wood. For a technology to make a difference it doesn't just need to be efficient, it must also be affordable and useable by everyone.

i_am_proteus 5y ago
"Heat pump" typically refers to a refrigeration cycle unit that uses a working fluid to transfer heat from a cold body to a hot body. An air conditioner uses this mechanism to heat the outside of the home (cooling the inside). Technically electricity is not required, although most of these units, in practice, use electricity, converted to mechanical energy, to power compressors. Heat pumps are much more efficient than e.g. electric baseboard heating because the energy consumed is used to move heat, rather than to generate heat. The efficiency difference drops in "very" cold climates (ambient temperatures well below freezing) and in those climates the heat pump usually is backed up by a direct heating method such as resistance electric heating, gas furnace, et cetera.
- deleted 5y ago
  [deleted]
stormbrew 5y ago
As sibling reply said, while peltier elements are technically heat pumps they're not the kind that's used in home heating. There are two things that make them much more efficient in terms of GHG than other kinds of heating: - Using central electricity generation means using more efficient combustion. Where I live most heating is done by gas and it is extremely inefficient compared to even a gas power plant. This is why we use central electricity generation to begin with; everyone running their own generator would be extremely bad for the environment. Even if it was 1:1 generated energy input to heat it would still be better for the environment for me to be using that generated electricity than directly buring gas in my home. Also as you allude to but dismiss, much of the electricity cost can be offset by using solar or wind directly at site, and it's likely that eventually most central generation will switch off GHG emitters and if/when it does you will automatically go with it. - Heat pumps with a refrigerant cycle don't use 1:1 energy input to heat produced. They're moving energy, not producing it as burning, resistive, or even thermoelectric do. So long as conditions are right, heat pumps only use a fraction of the energy they bring into your home. So the efficiency gains are compounding here. At any rate, it's simply not feasible to convert all heating to wood burning, even if it is efficient. As the article points out the last time this was done they basically caused intense deforestation and likely there were climate effects from that. The idea that now, with several billion more people on the planet, we can do it again but get it right this time is absurd. We will never be able to plant trees on the scale necessary to do this, never mind the transportation costs (in terms of both environmental and monetary) of shipping a bunch of wood around to homes all over the place to keep them heated. At any rate, we're likely to start needing tech like heat pumps a lot more as climate change accelerates. There are parts of the planet that are likely to become basically unliveable without AC soon, and as the heat dome last year showed even 'cold' areas are likely to start experiencing heat levels they're unable to really manage (up here in the north we build homes to hold heat in. Guess what that's like in a heat dome).

i_am_proteus 5y ago

"Heat pump" typically refers to a refrigeration cycle unit that uses a working fluid to transfer heat from a cold body to a hot body. An air conditioner uses this mechanism to heat the outside of the home (cooling the inside). Technically electricity is not required, although most of these units, in practice, use electricity, converted to mechanical energy, to power compressors. Heat pumps are much more efficient than e.g. electric baseboard heating because the energy consumed is used to move heat, rather than to generate heat. The efficiency difference drops in "very" cold climates (ambient temperatures well below freezing) and in those climates the heat pump usually is backed up by a direct heating method such as resistance electric heating, gas furnace, et cetera.

deleted 5y ago
[deleted]

stormbrew 5y ago

As sibling reply said, while peltier elements are technically heat pumps they're not the kind that's used in home heating. There are two things that make them much more efficient in terms of GHG than other kinds of heating: - Using central electricity generation means using more efficient combustion. Where I live most heating is done by gas and it is extremely inefficient compared to even a gas power plant. This is why we use central electricity generation to begin with; everyone running their own generator would be extremely bad for the environment. Even if it was 1:1 generated energy input to heat it would still be better for the environment for me to be using that generated electricity than directly buring gas in my home. Also as you allude to but dismiss, much of the electricity cost can be offset by using solar or wind directly at site, and it's likely that eventually most central generation will switch off GHG emitters and if/when it does you will automatically go with it. - Heat pumps with a refrigerant cycle don't use 1:1 energy input to heat produced. They're moving energy, not producing it as burning, resistive, or even thermoelectric do. So long as conditions are right, heat pumps only use a fraction of the energy they bring into your home. So the efficiency gains are compounding here. At any rate, it's simply not feasible to convert all heating to wood burning, even if it is efficient. As the article points out the last time this was done they basically caused intense deforestation and likely there were climate effects from that. The idea that now, with several billion more people on the planet, we can do it again but get it right this time is absurd. We will never be able to plant trees on the scale necessary to do this, never mind the transportation costs (in terms of both environmental and monetary) of shipping a bunch of wood around to homes all over the place to keep them heated. At any rate, we're likely to start needing tech like heat pumps a lot more as climate change accelerates. There are parts of the planet that are likely to become basically unliveable without AC soon, and as the heat dome last year showed even 'cold' areas are likely to start experiencing heat levels they're unable to really manage (up here in the north we build homes to hold heat in. Guess what that's like in a heat dome).