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I found this helpful in describing a bit about how to build such a system. As someone that operates solar, it's become quite clear that solar gives very little

I found this helpful in describing a bit about how to build such a system. As someone that operates solar, it's become quite clear that solar gives very little energy in the winter and water heating is a huge part of winter power use. So if you're going off grid, this seems like a critical part. Now if we just had some better tech around turning felled trees into a furnace without so much human effort....

eliaspro 5y ago
We're using 2 Paradigma water-based vacuum tube solar panels and pull even during the coldest winter days around 20kWh of thermal energy for hot water/heating out of them - even with just passive/diffused sunlight. Only on really dark/cloudy days it might just get us 1-3kWh. As fallback we still use natural gas, the wood burner which is also integrated in the hot water circuit is out of service since several years, as I just couldn't run it anymore with a good conscience knowing the extreme pollution those cause and the fact that burning wood is possibly the worst thing CO2-wise one could do given the current state of affairs.
- JshWright 5y ago
  Burning wood is certainly polluting, but CO2 is not the concern. The CO2 released by burning the wood was already part of the global CO2 "budget". As wood is burned, releasing CO2, more wood is grown, capturing it again. Wood burning, from a CO2 perspective, is effectively neutral, and far from "the worst thing".
- bacon_waffle 5y ago
  > burning wood is possibly the worst thing CO2-wise one could do given the current state of affairs. I'm curious about this. Around here the carbon from the wood (less emissions from a relatively small amount of petrol to cut and transport it) would've been taken out of the atmosphere in the last 20-ish years, where the natural gas carbon is in the millions of years (and additionally a much longer supply chain). I understand that smoke particles are not great in the short term, but assume we're talking about modern equipment.
  - BurningFrog 5y ago
    Wood is a renewable and carbon neutral energy source. OP is right that it's dirty as hell, by modern standards.
    - rmah 5y ago
      Burning wood is only carbon neutral if you plant and grow trees to replace the ones you burnt. It surprises many people just how many trees need to be grown to heat a single home for a year.
      - alamortsubite 5y ago
        Is that true? Firewood comes from downed/dead trees (unless a tree is felled for some other reason). I thought the same amount of carbon was released whether a dead tree rotted on the ground or was burned for heating.
        meepmorp 5y ago
        Burning the wood is taking carbon that would've been largely recycled as in ground biomass and converting it to heat + carbon oxides + particulates. There's an equivalent amount of carbon at all times, but the form it's in matters a lot.
  - eliaspro 5y ago
    This is one of the greatest achievements of the Biomass industry - marketing wood as "renewable" and "carbon neutral". First and foremost - at a time, when every bit of CO2 not emitted counts, we should be happy about CO2 being fixated in trees - once it's released, it doesn't matter whether the it is coming from jet engines or wood - the effect on climate change is the same. Furthermore, burning wood is quite inefficient in terms of mass/energy gain - even worse than coal. But besides that, there are a lot of systematic effects which make wood a non-neutral source of energy and making use of it as energy source comes with a lot of issues. Even if wood would be completely neutral, it would still be negative due to the energy required to harvest, process and transport it. Trees don't only sequestrate carbon in wood, but also in the forest soil through their roots. Decaying wood is processed by microorganisms and mycelium in the soil, so it's not only about the tree itself capturing CO2, but also about it being part of a more complex sequestration system which is disturbed by removing the tree. Cutting down single trees from an otherwise intact forest as part of a "sustainable forestry" strategy is actually often quite problematic, as the sudden exposure to sun & weather leads to decreased survival rates of fresh growth, but also soil erosion and thereby CO2 release - not even taking the damage of harvesting machinery etc. into account. Those "wounded" forests decrease the Earth's Albedo which also adds to climate change. Last but not least are forests not simply something that can be "renewed" by replanting trees, but are extremly complex ecosystems which might take millenia to build up. Right now, we're cutting down massive amounts of old growth around the world which can never be properly restored - we're far from managing wood like a crop on designated "farms". With technologies available like Passivhaus construction, heatpumps, solar and/or geothermal energy, there's zero reason to add to our systemic issues by using wood as an energy source. When it comes to particle and toxic emissions, there isn't a single non-industrial wood burner that would only come close to the emissions of a gas or oil furnace (not saying they're good, as they're using fossil fuels). The best even modern filters will get you is still worse by factor of ~400-500 compared to oil.

eliaspro 5y ago

We're using 2 Paradigma water-based vacuum tube solar panels and pull even during the coldest winter days around 20kWh of thermal energy for hot water/heating out of them - even with just passive/diffused sunlight. Only on really dark/cloudy days it might just get us 1-3kWh. As fallback we still use natural gas, the wood burner which is also integrated in the hot water circuit is out of service since several years, as I just couldn't run it anymore with a good conscience knowing the extreme pollution those cause and the fact that burning wood is possibly the worst thing CO2-wise one could do given the current state of affairs.

JshWright 5y ago
Burning wood is certainly polluting, but CO2 is not the concern. The CO2 released by burning the wood was already part of the global CO2 "budget". As wood is burned, releasing CO2, more wood is grown, capturing it again. Wood burning, from a CO2 perspective, is effectively neutral, and far from "the worst thing".
bacon_waffle 5y ago
> burning wood is possibly the worst thing CO2-wise one could do given the current state of affairs. I'm curious about this. Around here the carbon from the wood (less emissions from a relatively small amount of petrol to cut and transport it) would've been taken out of the atmosphere in the last 20-ish years, where the natural gas carbon is in the millions of years (and additionally a much longer supply chain). I understand that smoke particles are not great in the short term, but assume we're talking about modern equipment.
- BurningFrog 5y ago
  Wood is a renewable and carbon neutral energy source. OP is right that it's dirty as hell, by modern standards.
  - rmah 5y ago
    Burning wood is only carbon neutral if you plant and grow trees to replace the ones you burnt. It surprises many people just how many trees need to be grown to heat a single home for a year.
    - alamortsubite 5y ago
      Is that true? Firewood comes from downed/dead trees (unless a tree is felled for some other reason). I thought the same amount of carbon was released whether a dead tree rotted on the ground or was burned for heating.
      - meepmorp 5y ago
        Burning the wood is taking carbon that would've been largely recycled as in ground biomass and converting it to heat + carbon oxides + particulates. There's an equivalent amount of carbon at all times, but the form it's in matters a lot.
- eliaspro 5y ago
  This is one of the greatest achievements of the Biomass industry - marketing wood as "renewable" and "carbon neutral". First and foremost - at a time, when every bit of CO2 not emitted counts, we should be happy about CO2 being fixated in trees - once it's released, it doesn't matter whether the it is coming from jet engines or wood - the effect on climate change is the same. Furthermore, burning wood is quite inefficient in terms of mass/energy gain - even worse than coal. But besides that, there are a lot of systematic effects which make wood a non-neutral source of energy and making use of it as energy source comes with a lot of issues. Even if wood would be completely neutral, it would still be negative due to the energy required to harvest, process and transport it. Trees don't only sequestrate carbon in wood, but also in the forest soil through their roots. Decaying wood is processed by microorganisms and mycelium in the soil, so it's not only about the tree itself capturing CO2, but also about it being part of a more complex sequestration system which is disturbed by removing the tree. Cutting down single trees from an otherwise intact forest as part of a "sustainable forestry" strategy is actually often quite problematic, as the sudden exposure to sun & weather leads to decreased survival rates of fresh growth, but also soil erosion and thereby CO2 release - not even taking the damage of harvesting machinery etc. into account. Those "wounded" forests decrease the Earth's Albedo which also adds to climate change. Last but not least are forests not simply something that can be "renewed" by replanting trees, but are extremly complex ecosystems which might take millenia to build up. Right now, we're cutting down massive amounts of old growth around the world which can never be properly restored - we're far from managing wood like a crop on designated "farms". With technologies available like Passivhaus construction, heatpumps, solar and/or geothermal energy, there's zero reason to add to our systemic issues by using wood as an energy source. When it comes to particle and toxic emissions, there isn't a single non-industrial wood burner that would only come close to the emissions of a gas or oil furnace (not saying they're good, as they're using fossil fuels). The best even modern filters will get you is still worse by factor of ~400-500 compared to oil.