Winter in many Australian country towns is accompanied by a pall of smoke from wood-fired heaters that lasts from late afternoon to the following morning. In larger towns and cities burning wood has been limited by laws to reduce the impact of smoke on respiratory health. This is not a significant concession, given that other sources of heat, with much lower emissions, are available.
The majority of heat and electrical energy we use is recovered from oxidizing compounds of mainly carbon or carbon hydrogen and oxygen, usually by combustion of fuel in a furnace. When fuel is burned, a variety of compounds are released with the energy. These include organic molecules of varying molecular weights, carbon, carbon dioxide, carbon monoxide, hydrogen, water, oxides of nitrogen and sulphur, ammonia, and others. Of course the products of combustion are dependent on the fuel composition.
Burning wood produces all the compounds listed above with the exclusion of sulphur oxides. These are more commonly a product of coal or, to a lesser extent, gas combustion, and are noted to produce acids in the atmosphere that fall as rain. Natural gas is a primarily a mix of gaseous alkanes (CnH2n+1) and some minor compounds such as hydrogen sulphide. Burning natural gas produces larger amounts of lower molecular weight compounds compared to wood, and because these can quickly distribute with the same compounds in the atmosphere, burning gas is considered to be cleaner. In addition, burning wood produces heavy compounds as liquids and solids. Smoke, as an example, is particulate carbon and minerals.
In Australia, particulate emissions are broadly limited to particles 10 micrometers in size and at a concentration of no more than 50 micrograms per cubic meter. This air appears clear to the naked eye. Particles of this size are very small and are drawn deep into the lungs when breathing. They are considered to be responsible for respiratory and cardiovascular disease in some cases. Liquid products (tar and organic solvents) can also be drawn into the lungs if suitably exposed, and additional health impacts can occur. Any (educated) smoker will agree.
The products of wood combustion can also be varied with the temperature of combustion. For example, more wood is converted to relatively harmless gasses and water if the temperature of combustion is high (>1000°C). Particulate emissions are much reduced due to more complete oxidation of carbon compounds. Lower temperature combustion produces less energy because some compounds remain incompletely burned and pass up the chimney. Open fires and slow-combustion heaters are less clean than burning natural gas. However, new wood-burning technologies, including secondary higher-temperature burning and catalytic conversion of primary products, are substantially cleaner and their use has been legislated in parts of the US and Europe.
Any discussion like this should consider the issue of atmospheric carbon emissions, and of course any biomass combustion represents no net increase in greenhouse gas concentration. Fossil fuels on the other hand are primary contributors. It appears that completely clean energy production will be achieved only where biomass is converted to fuel and/or energy with sufficient scale to cost efficiently incorporate technology for the control of emissions.
The economics of energy production and price is unfortunately a maze of scale, fuel, markets, technology, legislation, regional economic circumstances, and the list goes on. There is no single global solution. One easy observation is that if an individual collects wood with little or no monetary cost, and burns this to produce heat for warmth and cooking, then this is as economically efficient as an individual might become. This is probably the least clean of all options, but to argue against such freedoms of activity is difficult on cultural or economic grounds. To then impose an increasing cost on the alternatives is even more difficult to justify. Fortunately there are still places where individuals can grow and use wood for heating and cooking, and we are all free to choose to live in these places. These places should also be conserved in Australia.

Another easy observation is that with good building design, the need for heating energy and spending money is significantly reduced. Many households that seek the open fire tradition or comfort have a fire place and are usually older dwellings with no insulation in the walls or ceiling. Is it reasonable that this tradition and comfort be limited to the camp site or barbecue from time to time?
With rising fuel and energy costs, the use of wood obtained at no or low cost could save many households money and in rural households where incomes are lower, this saving is important. Where population density is high however, more people risk more concentrated exposure to the products of burning wood fuel over sustained periods. The population density is defined indirectly by the acceptable limits on particulate emissions. There are, and should be, controls to minimise the risk to people in populated areas who are susceptible to health impacts of particulate pollution. Burning wood is controlled in these places because there are just too many air-breathing people over small spaces to maintain a healthy environment. It is noteworthy that the cost of wood-fuel in urban areas, or the rising cost of gathering and transporting it to town, soon diminishes any economic advantage.
Infrequent and short term exposure to wood combustion products, for most people, does not threaten health. In rural Australia after 60,000 years, fire is still used in land management, and fires are started naturally all the time, without worrying consequences for rural people. With larger distance between households in the rural landscape, wood is still used cost efficiently for heating and cooking. At the same time there is nothing healthy about countless wood fires in the suburbs or towns, and there are good alternatives such as natural gas.
The argument that the romance of open fires should risk community health is weak. However, the discussion raises an important issue. There is an engineering challenge to be faced here, to provide clean biofuel combustion at any scale to consumers. In this circumstance all combustible industrial and domestic waste becomes a source of energy that can replace costlier imported fuels. A history of exploiting cheap fossil fuels has discouraged development, however.
Comments welcome below.
Diana Taylor
retired psychotherapist
I am in the process of considering a change from my combustion wood heater to an alternative heat supply. Where I live, this means either electricity or LPG gas. Does anyone have the figures to determine the carbon footprint and the economics for these three options?
Mike Hansen
Mr
According to Matthew Wright from Beyond Zero Emissions, a good quality reverse cycle air conditioner is the way to go.
http://beyondzeroemissions.org/media/newswire/why-i-have-six-air-conditioners-111011
Mike Hansen
Mr
Diana
Here is the same article on Climate Spectator with Matthew responding to his critics in the comments.
http://www.climatespectator.com.au/commentary/why-i-have-six-air-conditioners
Stiofán Mac Suibhne
Contrarian / Epistemologist
What about a pellet fire?
Stephen Pritchard
Researcher, cognitive science
ECONOMICS
most cost effective (running costs only):
reverse cycle A/C*
not sure how exe wood is
least cost effective (running costs):
electric resistance heating
LPG gas
obviously you can buy a cheap electric resistance heater at bargain basement prices though.
CO2
Least co2:
efficient wood fire (presuming you use a renewable source of wood, not clearing land etc)
Mid co2:
LPG gas and reverse cycle a/c
Worst co2:
electric resistance heating
Note:
Read moreWhile reverse cycle…
Diana Taylor
retired psychotherapist
Never heard of them. what are the pellets made from? Can they be used in a wood heater? what is the carbon footprint making and transporting the pellets? What emission from burning them?
Diana Taylor
retired psychotherapist
Thanks for the url, Mike. Very interesting reading and I had not thought of air-conditioners as heat pumps.
Ian Ashman
Manager
Diana, the Europeans are miles ahead on high efficiency wood heaters and boilers.
The two 'cleanest' options are (I think) pellets and manufactured wool logs.
Have a look at:
http://www.dulas.org.uk/biomass.cfm
http://www.morsoe.com/Mors%C3%B8---the-environment-1106.aspx
http://www.pelletheaters.com.au/
and
http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12570
Byron Smith
PhD candidate in Christian Ethics at University of Edinburgh
I'm no expert in these things, but I would have thought that a ground-source heat pump would be the best option from an emissions perspective.
Stiofán Mac Suibhne
Contrarian / Epistemologist
This is an Australian supplier of pellets. Theyare made form saw dust that is crushed into pellets. Look rabbit food. Otherwise the sawdust goes to landfill where it will rot / ferment. So using burning pellets probably does not have a carbon foot print as such. Methane from fermentation has a more potent effect than CO2 as a greenhouse gas.
The pellets go the top of the fire in a reservoir and then drop one by one into a ceramic looking trough and then ignite. The combustion is very efficient…
Read moreDiana Taylor
retired psychotherapist
Thanks for the info. They are even located within driving distance from here near Wilsons Prom.
Matthew Thredgold
Software Engineer/Secondary Teacher
"The combustion is very efficient so virtually no particulate emissions. "
Not true.
Again that is an advertisement, and should be removed from this comment thread.
Stiofán Mac Suibhne
Contrarian / Epistemologist
It's a link to a website. Not an advertisement. So don't be silly. You may not like them and that is entirely acceptable. I understand that they have been restricted in some USA localities due to fire hazard.
Matthew Thredgold
Software Engineer/Secondary Teacher
Nope it's an advertisement for products that they (you?) are selling.
It's disingenuous to pretend otherwise.
Blair Donaldson
logged in via Twitter
Some winter evenings the outside air quality is terrible primarily because of wood smoke. Calm, frosty night seemed to be the worst. I often wonder how people with asthma get on when the air quality is so bad. Presumably they don't go outside more than necessary.
Dorothy L Robinson
logged in via email @gmail.com
Canberra Lung Life Support Group says “In most cases in our group, people affected by wood smoke have modified their lives, sealed their houses as well as they can, and limited the activities they do.”
In Canberra, in 2008, only 3.9% of households burned wood as the main source of heating (2.3% in 2011), but these households emit 71% of all particle pollution and 66% of PAH (polycyclic aromatic hydrocarbons, which include known human carcinogens such as benzo[a]pyrene). Pollution increases…
Read moreMichael Block
Idler
I agree, we are currently planning a new rural dwelling in the sub-alpine region of Victoria and we're planning for good insulation and solar hydronic as the only form of heating. There really is a pall of wood smoke on still winter days.
Stephen Pritchard
Researcher, cognitive science
When talking about wood smoke in rural areas, some mention of atmospheric inversion layers (e.g. http://en.wikipedia.org/wiki/Inversion_(meteorology)) and their contribution to wood smoke pollution would be good too, I think.
Wood smoke is probably more of an issue in the towns and cities in rural areas where there are lots of houses in an small area, where it gets cold, and where inversion layers are common (e.g., Armidale in NSW)
----
Also, when comparing different heating sources, wood…
Read moreStiofán Mac Suibhne
Contrarian / Epistemologist
I used to live in Christurch and there is terrible air quality issues in winter due to wood burning / inversion layer. The council had a programme to replace old style inefficient wood burners with clean burn ones, pellet fires and reverse cycle a/c it really started to make a difference. Pellet fires are excellent as they use saw dust from milling which is a waste product and an environmental nuisance in itself. There is no messy cleaning up dramas lighting the fires. I a, planning to install one in my house. This company is just getting through Australian red tape. The locally approved ones are less elegant / programmable but they do pump out heat. Combined with a heat transfer system one pellet fire will hear a whole house.
http://www.rika.at/en/B2C/
Diana Taylor
retired psychotherapist
Can the pellets be used with logs in a traditional wood heater?
Stiofán Mac Suibhne
Contrarian / Epistemologist
I dont think you can use pellets in a log burner. The pellets are v small. I presume in part so complete combustion can occur in the 'crucible'. They would fall through the slats in log burner and one of the major benefits of the pellet fire is its reduced emmission over log burners. There is just a little dust left afte several days use.
Matthew Thredgold
Software Engineer/Secondary Teacher
That is an advertisement for the pellet burning product. I think such an advertisement is inappropriate for a forum such as the Conversation.
Pellet fires do cause considerable pollution in their own right, and have been banned in some North American jurisdictions.
I'd hate for a neighbour to be relying on one, and if it caused a nuisance (which I believe they do) I would fight to get it removed. With all solid fuel fires the buyer should be aware that they could have a fight on their hands. It's better to go with a cleaner form of heating again than a pellet burner. Nothing dirtier than a gas fire should be the rule.
stib
logged in via Twitter
Every time I put the washing out. Every. Frickin'. Time. Thanks, elderly neighbours.
BTW what about the effect that open fires have of pulling cold air into a house and pumping hot air out the chimney, thus lowering the overall temperature of the house. This makes them actually less than 0% efficient, so they actually cool your house. (The Mythbusters did it so it must be true:
http://youtu.be/k17B6CFVeEA?t=9m19s )
Trevor S
Jack of all Trades
Good start to the investigation. We live in a rural area of Northern NSW and collect our own wood from coppiced trees which are therefore endlessly renewable. We are on our own small property (50 acres) and have no neighbours with-in 600m and then only one. We have a slow combustion wood heater, I am unsure of it's efficiency level but as discussed, open fireplaces are basically useless. We also cook on the trivet top occasionally, using it as a proover for bread, to heat stews and soups and keep…
Read moreChris O'Neill
Telecommunications Engineer
"..becomes a source of energy that can replace costlier imported fuels."
What does this mean? There is very, very little fuel imported to Australia used for home heating.
Gil Hardwick
Anthropologist
My view is that using firewood in country districts, especially in wooded areas, will never be stopped. There are many reasons for this, not just fuel efficiency, including distance from power lines, sustainability, charm and amenity.
The issue seems to be concerned with open fireplaces, when what country houses need is good solar passive design, good open-plan thermal mass and heavy insulation, and not least a good quality slow combustion stove and/or pot-belly enhanced with heat transfer pipes…
Read moreWil B
B.Sc, GDipAppSci, MEnvSc, Environmental Planner
A real issue is when fires are damped down overnight and basically smoulder. That's when emissions go through the roof. A modern Australian Standard wood fired burner, when burning hot, can be very clean, with very limited emissions. But an older model, slowly ticking over, is when I get cross at our neighbours.
Wil B
B.Sc, GDipAppSci, MEnvSc, Environmental Planner
Also, forgot to add, you can get a lot of extra bang for your buck with a wood-fired slow combustion heater by buying a 'wet-back' model, that heats your household water too. Nice and complementary with solar hot water.
Stephen Pritchard
Researcher, cognitive science
The "fires damped down overnight" issue applies to efficient slow combustion heaters too.
There is something of a tradeoff between efficiency of heat delivery (ie efficient use of energy) and particulate emissions.
Opening the grill and letting some air in means the fire burns hotter and there are less particulate emissions and partially combusted by products, but more heat is lost up the chimney.
Damping the fire down by closing the grill increases fuel burning efficiency, but the burn is at lower temps and there is more smoke.
Tracey OBrien
Feng Shui Consultant
We moved to a pristine valley in semi rural Southern Tas nearly 2 years ago. We have gone to great effort & expense to build a house that is environmentally sound and well suited to living on the side of a (small) mountain.Super insulated, double glazed timber windows, N. facing,
Read moresolar hot water etc.& a Daikin floor mounted Heat Pump adequately warms our 88squM not so big house.A healthy eco retreat on 3 acres, turns out to be the smokiest most toxic environment we've ever lived in. Although not…
Stiofán Mac Suibhne
Contrarian / Epistemologist
You should ask for air quality monitoring and get the public health / environmental health functions to take responsibility. Once there is data showing the air is injurious to health it becomes actionable and you can rightfully expect your local representatives / public servants to get a plan together to improve things. You are looking at cultural change and the weight of conventional thinking / practices weigh heavy. The myth of the rural idyll..
I remember the shock of my first winter in Christchurch NZ, when I first tastesd / smelled and coughed up the stench of wood burning. People were burning rubbish to save 50c a bag on the municipal collection. Hiddeous. It was ironic to be missing the clean air of London.
Tom Dawson
teacher
There is in fact a health risk to every person from wood smoke, and not just those with cardiac/respiratory problems. The author is seriously misinformed!
Ernest Grolimund
Engineer
Wood smoke smells indicate a health problem per health authorities. Health problems have to be stopped by law and public policy. Unfortuneately, the smells exist in the country as they do in the cities and driving in the country for a long distance to get to the cities, exposes people to unhealthy pollution causing stinging eyes and other health problems in even the healthy. The health problems from direct exposure and the indirect world wide health problems from global warming due to the black soot…
Read moreMatthew Thredgold
Software Engineer/Secondary Teacher
I have experiences I'd like to share living in 5 different places in Australia and New Zealand.
1. A suburb in Adelaide's North Eastern suburbs. Me I hardly used it, but I had an oil heater to heat and ceiling fans to cool. Quarterly electricity bills were about $66. (I lived alone), Neighbours heated with wood. Wood smoke was terrible. Local council was hopeless (and negligent in my opinion). I had to move because of the wood smoke. So I agree with the author. There should be a complete ban on…
Read moreNeed Clean Air
Business Analyst
I live in a neighborhood with pellet burning stoves. The toxics and particulate matter coming from the pellet stoves are very lung and sinus irritating. We have had a serious decrease in health in the neighborhood since it was installed. One smoke caused heart attack, numerous smoke caused asthma, chronic bronchitis, COPD, siuns infection and migraine attacks and/or diagnosis since the stove was installed. Multiple cancer diagnosis. One was lung cancer in a young person (40) who had never used tobacco…
Read more