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Comment by DickingAround | Hacker News Reader

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....

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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.

> 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.

Wood is a renewable and carbon neutral energy source.

OP is right that it's dirty as hell, by modern standards.

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.

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.

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.

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.

People aren't cutting down live trees to burn in their wood stoves.

Even if (which is far from the reality) only dead wood would be collected from the forest, it's still releasing CO2 which would otherwise be mostly sequestrated by microorganisms and fungi in the forest soil and provide a key ingredient to a functioning soil ecosystem.

The reality is: huge amounts of protected forests (e.g. in Romania or Estonia) are cut down and sold as firewood in central Europe.

Live trees are full of water, and take, in my experience, two years minimum after they die to season properly before their wood can be burned in a stove. If people are harvesting live trees for firewood, my guess is they're desperate for other options. I don't think that's the case in NZ (the context for this discussion), but I admit to being clueless about the situation in Central Europe.

Also, if a dead tree is laying on the ground and your options are 1) use it to heat your home, or 2) leave it the to mushrooms and bugs and burn fossil fuel instead, then if the environment is your concern, I don't see how you could pick the latter. Keep in mind that one of the best things about heating with wood is that it takes a tremendous amount of effort on the part of the end user. Cutting, splitting, stacking, starting a fire, feeding the stove, adjusting the stove, taking out the ashes. Some of us enjoy it, but it's definitely a lot of hard work, and I'd argue all the time you put into it makes you far more in touch with how much energy you consume than someone who simply twists a dial on the wall and kicks back to Netflix. You might even choose a much smaller house and wear a sweater.

I've hiked in a forest in Romania. Despite the fact that it was a great place to be eaten by a bear, it was spectacular and a resource to be treasured.

I'm pretty sure live trees are harvested, cut to length and split into firewood, dried for two years, and sold. It's sort of necessarily true that the trees used are dead. I think the point is: many are killed specifically to produce firewood.

Can you please provide a reference? Writing as someone with a wood stove, with neighbors with wood stoves, whose fuel comes from trees that are not felled for firewood, I'm very skeptical this is true in the context of the article we're discussing.

I can't, and it's entirely possible you're right about your wood and your neighbors.

Some of the wood I could buy in the U.S. is birch harvested in the Baltics. I've seen videos of harvesting operations that are definitely harvesting live birch and splitting it with equipment that's all designed with that in mind. But I've got no proof for you!

In NZ, pine trees are an invasive pest.

https://www.doc.govt.nz/nature/pests-and-threats/weeds/commo...

I can't imagine burning pine in a stove, except as kindling.

The notable invasive species where I live is ailanthus. I've burned some out of curiosity. It's better than pine, but not worth the trouble when you're tripping over red oak.

Pine is one of the most common firewoods here. I tend to go for gum, which is also an introduced species. And, yes that's often felled to be used only as firewood.

I should point out that there are plenty pine species that aren't considered invasive pests like wilding pines are; for example one of our bigger exports is radiata pine.

People did. That is largely a matter of scale.

Woodstoves are not widely used in major habitated areas (cities and suburbs) in advanced countries. They're a primary heating source principally in rural areas, where population is sparse. Or, of course, in developing countries where other heating options aren't available.

When woodfuel was a principle fuel source, forests were indeed being cut down faster than they could regrow just to provide fuel. And some of the oldest enviromental regulations and restrictions in the world address the sustenance and conservation of woodlands. The aphorism that "forests preceed mankind, deserts follow" has a great deal of truth to it. It was exhaustion of fuelwood throughout Great Britain, Ireland, and mainland Europe that lead to the adoption of coal, and the burning of coal which largely lead to the resurgence of European forests.

In developing countries, fuel avaiability and woodstove (or other solid fuel, often animal droppings) particulate emissions are major energy security and health concerns.

At small scale, and for occasional use, in areas with abundant tree growth, fuelwood is viable. Given present human population densities, at a large scale, it is not.

> Woodstoves are not widely used in major habitated areas (cities and suburbs) in advanced countries. They're a primary heating source principally in rural areas, where population is sparse. Or, of course, in developing countries where other heating options aren't available.

Unfortunately, that's not the case for large parts of Western Europe, where wood-based heating is considered eco-friendly, due to it being classified as "renewable". For example. in Germany you'll get 40% of a wood-pellet burner subsidized. Many villages and also towns are plagued by heavy air pollution. Emissions from those by now have surpassed those by cars, according to the German federal environmental agency. [1] Scientific findings and political action don't match up at all here - some other European countries slowly start to address this issue, but then again UK is pushing for the Drax power plant which runs exclusively on wood pellets whose wood sources are highly problematic [2].

[1] https://www.umweltbundesamt.de/daten/luft/emissionsminderung...

[2] https://www.biofuelwatch.org.uk/2021/draxs-pinewells-case-st...

I'm not contesting that fuelwood isn't a major particulate pollution source, where and when used.

I'm contesting that it's widely used.

Wood / pellet stoves in dense urban environments are a small fraction of total cooking and heating load.

And I'm also arguing precisely your point: that woodstoves widely used are a major pollution and deforestation issue.

They are here in Vermont. When a woodlot gets cut, high grade gets sawn for lumber, stuff that doesn't make the cut for saw logs but can be pulped becomes paper and stuff that doesn't work for either of the above becomes firewood.

There may be some variation based on pricing any given day, but my understanding is that this is pretty common when harvesting mixed forest (as opposed to a monoculture forest).

We got three cords delivered last year that was mostly black birch, red oak, and white ash, and we burned two, supplemented by propane that kept the overnight low around 50F/10C inside. Our hot water, incidentally, is tankless propane.

> When a woodlot gets cut, high grade gets sawn for lumber, stuff that doesn't make the cut for saw logs but can be pulped becomes paper and stuff that doesn't work for either of the above becomes firewood.

OK, but making complete use of the wood is hardly the same as harvesting timber specifically for firewood.

Also, relatively speaking, little of the species you're burning are used for lumber. And you can't throw a rock without hitting a dead ash tree these days.

Without starting a point-by-point rebuttal, I think we're talking a bit past each other. Here, there are a couple perspectives to consider:

You're a landowner and need to decide how to use your land (ed: which has already been cleared of native bush). Practically, the usual choices are something like:

  * Dairy farming
  * Subdivide and build residential sprawl
  * Crop farming
  * Forestry (introduced tree species)

Note that all of those can provide wood that's suitable for heating, however only two do it in a way that aren't clearly bad from a greenhouse gas standpoint. A lot of land here isn't suitable for crop farming, and generally crop farms don't have many wind breaks either.

Or, you're a homeowner and need to decide how to heat your existing, likely built to a low/nonexistent efficiency standard, house. Your choices are:

  * Heat pump, usually poorly located/installed
  * Electrical resistance heaters where needed
  * Burn wood
  * Burn coal

In the balance, I think wood heat is a pretty good compromise. Currently, our electricity is relatively "clean", but only because previous generations installed a bunch of hydro. At some stage, we'll hopefully have a better mix with wind and PV, and of course those do have costs too, but we're not there yet.

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".

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