Wood Heater Pollution and CO2

[AndrewJ]

Modern reactor designs insure no possibility of accidents like those in Japan.

Thats what the Japanese thought.
In the followup of that little episode, it was illuminating to see how the economics of designing for disaster scenarios, as well as running the units involved "corner cutting" by the operators.
ie You cannot design greedy operators out of any object, and forcing them to put aside a suitable amount of money for decommisioning will be nigh on impossible.
The money spent ( directly and indirectly ) by governments to clean up Chernobyl and Fukushima must be getting quite large by now.

Andrew

[sheeny (Al)]

Originally Posted by glend

I would like to remind respondents that burning wood in a device inside your house depletes oxygen from your air supply ( a wood fire needs oxygen to burn, as do gas heaters in homes). These devices also emit carbon monoxide as part of the combustion process, which can be deadly in itself. A properly designed flue system is needed to vent the combustion gases but it does not help with input air supply quality, you need to have outsude air coming in to sustain aur quality. So unless your wood heater has its own outside air source you are going to need to keep a window open. It scares me that people with young kids use these things, as these kiddies are much more susceptible to oxygen depletion and carbon monoxide buildup.

Not so, Glen.

The air in your house is NOT depleted of oxygen, because the air moves FROM the house TO the heater and not vice versa.

Carbon monoxide is a product of partial combustion. With adequate temperature and excess air in the heater, the flue gas contains minimal CO. We tune our solid biofuel (wood) furnaces at work to 0% CO (<40ppm) but a domestic heater doesn't have this sort of control. The correct chimney design ensures that the CO concentration by the time the gas gets to breathable zones is less than the safe exposure limits - but a leaky flue inside a building can be lethal!

An open window is NOT necessary to replace the air used by the heater. The volume of air used by the heater by easily replaced by the small amount of leakage through the gaps between windows and doors and their frames. This amount is not even enough to be a detectible breeze!

I don't have the stoichiometric calculations here to quote the air requirements for burning wood, but I as I frequently tune wood fire furnaces at work I have the data and I have a good appreciation of the real world implications.

People turning to wood burning in response to electricity, or gas, price increases, is perhaps a natural response in a country without any sort of national energy policy. The lack of leadership is incredible. Having lived in Sydney, i know how pollution can hang in that bowl east of the Blue Mountains, and bush fire smoke can linger there. Is there actually a no burning policy in Sydney? I seem to recall a ban on back yard incinerators, don't wood heaters fall into the same category?

Absolutely, not. A properly designed incinerator is required to have a minimum residence time above a certain temperature to ensure complete combustion of what you are trying to destroy. The backyard "incinerators" to which you refer are too small to provide adequate residence time for anything other than clean dry paper and wood. That's the problem - people burn rubbish in them not clean dry paper and wood. This is also why you should never burn anything in your wood heater other than clean dry wood (and perhaps a little bit of paper to get it started).

Burning colour printed pamphlets in a wood heater or back yard incinerator will emit a cocktail of heavy metals in the flue gas, plastics will produce VOC's and all manner of partially combusted organic compounds with all sorts of adverse health effects.

So, no, incinerators and not the same thing as heaters.

Craig i am a big fan of Australian nuclear power.. we are self sufficent in uranium. Modern reactor designs insure no possibility of accidents like those in Japan. Canada has been doing some great design work in this area. If total cost is considered nuclear is expensive due to build cost. Fusion is the ultimate answer, as i was reminded of watching " Back to the Future" last night, sign me uo for a Mr Fusion unit.

I am in two minds about fission power. To me it seems to be a big compromise, a bit like the current electric cars. When we get fusion power, now that should be much safer and better for the environment.

Al.

[xelasnave]

Originally Posted by UniPol

http://www.health.nsw.gov.au/environ...ood-smoke.aspx

That's from the government are you going to believe them
Alex

[Renato1 (Renato)]

Just a warning to others with wood heaters, as a few months ago our wood heater nearly burned our house down.

What happened was that after getting the flue cleaned last year, it was working very well, and I was lighting it during the day at a low level, then putting more wood in at night. And the wood I used was all the dead wood on my property and that which my neighbour gives me - and it wasn't hardwood.

As a result big crystal-like bits of soot formed within the flue, which one day - when I was in hospital - came crashing down to the base of the flue and blocked it. As a result of which the flue started glowing red hot and heating the wooden ceiling. My wife called the Fire Department, who put it out slowly using my big garden fire hose, and made sure with their device that the ceiling heat receded rather than started burning.

The wood heater repair plumber said that for best operation, I should have used hard wood, or to at least have mixed hardwood with what I was burning. So now I only light it at night, and make it burn very, very hot to ensure those soot crystals don't form. During the day I use a reverse cycle air-conditioner for heating.

Being on an acre property, like the rest of my neighbours, wood heaters aren't an issue around here, except that I know it's pointless trying to observe planets in the direction of the flue.
Regards,
Renato

[Nebulous (Chris)]

Originally Posted by sheeny

Being a country dweller, I am all for wood heaters. However, I understand your irritation, especially when you see the down side and not the benefits, but they have their place. In the city or built up areas where you need to buy your firewood, and gas is readily available I think they are a luxury and not terribly appropriate.

SNIP .............

We do not have any problem with smoke smell in our clothing from the washing line, though it is rare we run the wood heater during the day.

Al.

+1

Good post Al. We're in much the same position - a country location and our own trees that die at a natural rate. We would have to wait for many years before a freshly cut down tree was seasoned enough to use for firewood. Even the firewood sold locally has been harvested as dry dead logs from the local forests.

Like you, I believe that a properly adjusted wood fire is not necessarily more harmful, in terms of producing pollutants, than any other form of home heating - if you look closely at the whole supply and production chain.

The major problem,as i see it, is population density. When you cram enough people together in a city you get more waste, of every kind, than can be disposed of simply. Many solutions just push the problem somewhere else on the "out of sight out of mind" principle.

To put it into perspective, when I was born in 1946 the population of the entire world was less than two and a half billion. Now it's already blown out to seven and a half billion. So, in the space of a single lifetime (which isn't quite over yet!) the population has trebled. The pressure on resources and environment is increasing at an unsustainable rate. Getting a little "greener" is clearly desirable, but if we keep breeding at that rate, recycling our beer bottles etc will only delay things by a few eye-blinks.

We all contribute to this. For instance, I'm personally addicted to breathing in oxygen and other gases and exhaling some of it as carbon dioxide. And it's not just me - my wife and son are addicted too. And we're addicted to food as well - we eat some almost every day. And it takes a lot of good land to keep us chomping away.... Water too (and we all know what humans turn that into...)

I don't have a firm opinion on nuclear power, but maybe if we could just nuke a few cities we could thin the population out a bit? Well, maybe not.... there's bound to be a fuss of some kind...

But IMO the greenest tool isn't an electric heater, it's a vasectomy knife...

Cross your legs fellers, I'm coming after you...

Cheers,

Chris

[Boozlefoot]

Well said Al, I can honestly say my wood heater emanating a heat haze rather than smoke uses less carbon than the alternatives. Wood heaters are the way to go if you have access to clean dry wood. Naturally, the home needs to have the necessary insulation to be frugal with wood. Don't let others fall into the trap that if you cut your own wood, it must be cheaper and you're a lucky fella. Consider the time involved, fuel, chainbar and chain wear. It still costs. Even here in Windeyer, the wood is getting scarce as the bulk cutters have moved in and are taking huge truck and dog loads to the city. Now, not being picky, but in the bush we learn fairly quickly to be practical. A lot of the problems emanating from wood fires in the heavily populated areas are caused by inexperience and the use of the "bag" lots of wood which are not only expensive but often contain unsuitable or unseasoned fuel. Horses for courses.

[el_draco (Rom)]

Originally Posted by Nebulous

But IMO the greenest tool isn't an electric heater, it's a vasectomy knife...

Cross your legs fellers, I'm coming after you...

Cheers,

Chris

SWEET!! Can I hold some candidates down for you... Doesn't matter if the knife is blunt either...

[Nebulous (Chris)]

Originally Posted by el_draco

SWEET!! Can I hold some candidates down for you... Doesn't matter if the knife is blunt either...

What a team we'll make! We'll sort the planet out in no time.

[sheeny (Al)]

There are several factors that influence the build up of both soot and creosote in chimneys:

1. Burning some softwood species ANECDOTALLY causes creosote build up. I have been warned about burning willow for this reason, however, I have successfully burned nearly a tonne of dry willow blended in amongst hardwood without any evidence of creosote buildup. I noticed a piece in the wood heap the other day, so I still have the odd piece of willow kicking around, but I basically burned the tonne of willow over two years in probably about 4-5 tonnes of wood total.

2. Lighting a fire and throttling the air before the fire and flue has gotten fully up to temperature. A cold flue and a small fire (for the flue size) results in the steam from the moisture of combustion condensing in the flue. The soot and creosote get trapped in the moisture layer and stick to the walls of the flue before being emitted. When it does heat up, it gets baked into place. As the cycle repeats, the soot and or creosote builds up.

3. Burning green wood (i.e. not properly dry or seasoned) greatly increases the chances of soot and creosote build up in chimney because the extra moisture means there's more steam to condense in the flue and it takes more energy to evaporate it so, the fire doesn't burn as hot. This in turn doesn't heat the flue enough, so the condensation and build up occurs.

Best advice is to make sure your wood is truly dry (seasoned) and allow the fire to get up to full temperature before throttling the air.

Fortunately once the pyrolysis phase of the fire is past, (i.e. all the volatiles have been flashed out of the wood and burned and you are no longer adding new wood) the burning coals are predominantly carbon, so the combustion reaction is C + O = CO and CO + O = CO2 with no water of combustion produced, so as the fire dies down you don't have a creosote or soot buildup problem as there's no steam to condense.

Al.

Originally Posted by Renato1

Just a warning to others with wood heaters, as a few months ago our wood heater nearly burned our house down.

What happened was that after getting the flue cleaned last year, it was working very well, and I was lighting it during the day at a low level, then putting more wood in at night. And the wood I used was all the dead wood on my property and that which my neighbour gives me - and it wasn't hardwood.

As a result big crystal-like bits of soot formed within the flue, which one day - when I was in hospital - came crashing down to the base of the flue and blocked it. As a result of which the flue started glowing red hot and heating the wooden ceiling. My wife called the Fire Department, who put it out slowly using my big garden fire hose, and made sure with their device that the ceiling heat receded rather than started burning.

The wood heater repair plumber said that for best operation, I should have used hard wood, or to at least have mixed hardwood with what I was burning. So now I only light it at night, and make it burn very, very hot to ensure those soot crystals don't form. During the day I use a reverse cycle air-conditioner for heating.

Being on an acre property, like the rest of my neighbours, wood heaters aren't an issue around here, except that I know it's pointless trying to observe planets in the direction of the flue.
Regards,
Renato

[w0mbat (Ian)]

Having worked in the nuclear industry for 20 years and perhaps because of that experience I would have absolutely nothing to do with Nuclear Power where there was any profit motive involved and would have serious doubts even with a government run nuclear power plant.
The problem is that in the admittedly unlikely case of a significant accident you have an absolutely massive problem likely to cost billions to rectify even if that is possible at all. It is human nature that eventually someone will cut a corner or try to economise once too often and then....disaster.
Simply not worth the risk.
And then there is the timing problem. Nuclear plants are massively complex, slow and expensive to build. We need a much faster response to climate change than nuclear can provide.
And then there is the waste......and so on and so on. Problem after problem.
I believe nuclear will make an insignificant contribution to solving the problems we have.
Ian

[raymo]

Nuclear contribution can hardly be insignificant when many nuclear
stations are already running around the world,[ and have been for many, many years],and not emitting the pollutants that traditional stations would
have done.
How much pollution would traditional stations have produced in that time?
Our present situation would be significantly worse if those nuclear stations
had never existed. Obviously the waste problem still remains.
raymo

[Renato1 (Renato)]

Originally Posted by sheeny

There are several factors that influence the build up of both soot and creosote in chimneys:

1. Burning some softwood species ANECDOTALLY causes creosote build up. I have been warned about burning willow for this reason, however, I have successfully burned nearly a tonne of dry willow blended in amongst hardwood without any evidence of creosote buildup. I noticed a piece in the wood heap the other day, so I still have the odd piece of willow kicking around, but I basically burned the tonne of willow over two years in probably about 4-5 tonnes of wood total.

2. Lighting a fire and throttling the air before the fire and flue has gotten fully up to temperature. A cold flue and a small fire (for the flue size) results in the steam from the moisture of combustion condensing in the flue. The soot and creosote get trapped in the moisture layer and stick to the walls of the flue before being emitted. When it does heat up, it gets baked into place. As the cycle repeats, the soot and or creosote builds up.

3. Burning green wood (i.e. not properly dry or seasoned) greatly increases the chances of soot and creosote build up in chimney because the extra moisture means there's more steam to condense in the flue and it takes more energy to evaporate it so, the fire doesn't burn as hot. This in turn doesn't heat the flue enough, so the condensation and build up occurs.

Best advice is to make sure your wood is truly dry (seasoned) and allow the fire to get up to full temperature before throttling the air.

Fortunately once the pyrolysis phase of the fire is past, (i.e. all the volatiles have been flashed out of the wood and burned and you are no longer adding new wood) the burning coals are predominantly carbon, so the combustion reaction is C + O = CO and CO + O = CO2 with no water of combustion produced, so as the fire dies down you don't have a creosote or soot buildup problem as there's no steam to condense.

Al.

Thanks Al,
That was very informative and comprehensive.

My wood is pretty much dry, most of the greener stuff having been left in my woodshed for at least a year, if not two. I think that No2 is mainly to blame for our issue, though the plumber was adamant about the hard wood - claiming that some people living in areas where there is only hard wood available have sometimes not cleaned their flues for over 30 years.

Regards,
Renato

[sheeny (Al)]

Originally Posted by Renato1

Thanks Al,
That was very informative and comprehensive.

My wood is pretty much dry, most of the greener stuff having been left in my woodshed for at least a year, if not two. I think that No2 is mainly to blame for our issue, though the plumber was adamant about the hard wood - claiming that some people living in areas where there is only hard wood available have sometimes not cleaned their flues for over 30 years.

Regards,
Renato

Yeah, there's a lot of variables behind that statement Renato. That's why I emphasized the anecdotal nature of it. I've heard similar stories, but if there's real fact behind it, it would have to be due to a biological (and indeed chemical) difference between hardwood and softwood that I'm not aware of.

The reason I am skeptical is that 100% of the wood fuel we burn at work is softwood (radiata pine and radiata pine bark plus traces of additives such as resins), and we have NO evidence of creosote formation and while we get fly ash build ups, they aren't building up in condensation layers. Radiata pine is typically 1% ash, while bark is 6% ash but has a higher calorific value so we burn both.

Al.

[glend (Glen)]

Look for folks living out in the bush, with access to the fuel, it makes sense, but not in suburbia. Try aiming your telescope over a heat plume four houses away, or even on the next street. Doesn't matter if your visual or imaging, your stuffed in that direction. It's at its worse on nights when seeing is at its best. And i can testify that many of these people are starting their fires with any rubbish they have on hand, including plastic. They stuff the heater with wood and it takes forever to reach operating temperature, smoking like an old coal fired steam train. Any idiot can buy one, there is no requirement to know how to do it, or what they should burn. I watched a guy break up some old treated pine garden furniture and take it inside to burn. On a still night, like last night, the smoke haze hangs over the area with haze light cones around any street lights. I go outside and my jacket smells like smoke within minutes. It has to be controlled, and its only getting worse.

[xelasnave]

I will drop by start digging some holes.

Yes Glen its not right but please don't let it upset you.
There is nothing worse.
Maybe print off the sheet linked above wherein the Dept of Health listed the problems...then letter box drop the region.
Hand them out at the shopping center and tell folk you are trying to prevent cancer in children.

You have a genuine complaint but as I said don't get upset ..it is not good for you.

Alex

[sheeny (Al)]

Originally Posted by glend

Look for folks living out in the bush, with access to the fuel, it makes sense, but not in suburbia. Try aiming your telescope over a heat plume four houses away, or even on the next street. Doesn't matter if your visual or imaging, your stuffed in that direction. It's at its worse on nights when seeing is at its best. And i can testify that many of these people are starting their fires with any rubbish they have on hand, including plastic. They stuff the heater with wood and it takes forever to reach operating temperature, smoking like an old coal fired steam train. Any idiot can buy one, there is no requirement to know how to do it, or what they should burn. I watched a guy break up some old treated pine garden furniture and take it inside to burn. On a still night, like last night, the smoke haze hangs over the area with haze light cones around any street lights. I go outside and my jacket smells like smoke within minutes. It has to be controlled, and its only getting worse.

These are all real problems, Glen. Burning treated pine is especially bad due to the cyanide!

Regulation isn't he answer IMO. Australia as a society is over-regulated. I read something the other day that I initially took offense at, but on reflection realized that they were right... Australia is over regulated because we are a nation of fools... we regulate to protect the fools and we are fools for regulating to protect the fools. But that's a whole other debate.

FWIW I just went outside to check my chimney. Absolutely no smoke. The firebox is about 40% full and the air damper is about 40% open (which is the spot I've empirically worked out gives me best heat output out of the heater).

I was at a bonfire last night (the bonfire itself was cancelled due to fire risk but we had a fire in a fire pit). I tried a few shots around the fire and was quickly reminded that photography through a heat plume is worthless. Heat plume from houses and especially chimneys are no good for seeing. It's a disadvantage of being and astronomer in a built up area.

Al.

[skysurfer]

I have a wood stove as well.
But I only burn dry seasoned oak and beech wood which burn very hot. I never burn impregnated, treated or green wood, not to say plastics.
To set fire to it, I use two lighter blocks (smell like kerosene), put them on the logs and that's all.
And I let clean my flue every year.

One problem still with wood stoves is particulate matter. I never understood why there are no PM filters available for woodstoves. When it is foggy, many woodstoves per sq km can cause a problem as the PM is not blown away.
The extra heat exchanger between the flue pipe and the combustion chamber also captures some dust and PM, but by far not enough.

But PM is also a problem of automobiles. And the stinking and noisy two stoke engines (leaf blowers, mopeds) are far worse than autos or woodstoves. I never understood why two stroke mopeds are not completely banned (at least here in the EU).


EDIT: This topic also depicts energy in general. Mankind is the only species which uses external energy sources, like fossil fuel or nuclear. I have no problem with that, but the way we are now using excessive amounts calls for another approach.
We should, together with reducing CO2 emission from nonrenewable energy (this exempts properly burnt woodstoves as wood is renewable), also beat unnecessary energy consumption, such as lighting during daytime or air con enabled when it is not hotter than 20 C. I see that many times. Or short haul flights like Sydney-Canberra or even Sydney-Melbourne which can be replaced by high speed trains or, when that succeeds, hyperloop. But as long energy intensive air travel is heavily subsidized by all governments in the world, this won't work.
And it is already technically feasible to extract CO2 from the air and use this for making synfuel, for fueling air and ship travel of which are no electrical alternatives.

That costs a lot of money, but such stupid coal mine projects as Adani mine with a terminal port in the middle of the Great Barrier reef (may be funded by the AU federal government !) does cost $billions as well.

As long as such things like Adani mine continue, we should not worry at all about (hot and clean burning) wood stoves !

[UniPol]

http://theconversation.com/everyone-...worth-it-13536

[The_bluester (Paul)]

Originally Posted by glend

I would like to remind respondents that burning wood in a device inside your house depletes oxygen from your air supply ( a wood fire needs oxygen to burn, as do gas heaters in homes). These devices also emit carbon monoxide as part of the combustion process, which can be deadly in itself. A properly designed flue system is needed to vent the combustion gases but it does not help with input air supply quality, you need to have outsude air coming in to sustain aur quality. So unless your wood heater has its own outside air source you are going to need to keep a window open. It scares me that people with young kids use these things, as these kiddies are much more susceptible to oxygen depletion and carbon monoxide buildup.

With a properly designed wood heater I have to say that really neither of those stack up as arguments.

Burning wood (in a properly designed and maintained) combustion heater does not deplete oxygen in a house. That would require the heater to selectively intake only the oxygen and return the rest (Including combustion products) to the room. Air is taken in to support combustion, is exhausted through the flue and make up air has to flow into the house from outside. It would be an impressively airtight house that did not allow make up air to enter and I reckon you would notice a pretty sullen fire it it managed. And yes, a properly designed flue is certainly designed to exhaust combustion gasses, that goes without saying, as it does for a gas heater. At least safety wise you don't have to worry about the fuel gas as well as the combustion products.

[The_bluester (Paul)]

I should add that we have a wood heater as we live away from town gas and it is the only feasible way. I can not comment on the relative benefits of older stoves which could be damped right down and were more efficient thermally versus the new ones. Except that fan forcing is far more common now around the firebox so at least a bit more heat is captured that way. I have often thought of a flue heat exchanger so we can at least extract a bit more heat to help the solar hot water along in the winter months, where it is much less effective than in the summer.

All our firewood comes form fallen wood from our own property, but I have been thinking of a dedicated plantation on the place (We can spare the land) to be able to really lay claim to using a renewable heat source, particularly if we plant more than we use in the longer term.