« The Printed Website: Second Volume Out Now | Main | Low-tech Magazine in Spanish, French, and Other Languages »


Feed You can follow this conversation by subscribing to the comment feed for this post.



Whilst I have recently become convinced that civilisation was possibly humanity's worst mistake, one which looks set to kill us all eventually, there are some problems with this article.

Telling us that the wildfires which are causing many problems in Australia - and they are certainly a serious threat to life - are more damaging to humans than the use of controlled domestic fires does not seem to have good evidence.

"But with fire also came the first anthropogenic pollution, evidenced by the soot still found in prehistoric caves. Over the past few centuries about half of humanity has been able to afford to transition from traditional biomass fuels (wood, animal dung, crop residues such as rice husks, etc.) to fossil fuels such as kerosene or gas, or to electricity. The remaining half of humanity, almost all in developing countries, continues to use biomass fuels or coal, often in open fires or in inefficient, smoky stoves. Consequently, the United Nations Environment Programme/World Health Organization Global Environment Monitoring System (GEMS) has confirmed that the worst overall air pollution conditions and the largest indoor pollutant concentrations and exposures are found in both rural and urban areas of the developing world...

...Demand for traditional fuel also places significant pressure on local forests and woodlands, contributing to deforestation, soil erosion and desertification. Frequently, the need for wood is so great that reforestation attempts of badly degraded regions prove impossible because even young trees are rapidly harvested for cooking fuelwood or charcoal production."

"Stoves and open fires are the primary means of cooking and heating for nearly three billion people. In India, some 400,000 people die each year from the toxic fumes. In Africa, 500,000 children under the age of five die from pneumonia attributable to indoor air pollution, according to the WHO. And in Afghanistan, smoke from cooking and heating fires killed 20 times as many people in 2010 as did the ongoing conflict. Dr Nigel Bruce, consultant at WHO, said: "The problem is caused by the inefficiency of traditional open fires and stoves resulting in very incomplete combustion of wood, dung and other solid fuels that a majority of people in developing countries rely on for their everyday cooking needs.”

This does not seem consonant with the author's back-of-an-envelope calculation of the amount of land needed. Sorry, but this does not appear to be a realistic, healthy, sustainable or safe idea.

Graham Ford


Concerning your proposal of burning 6 cubic metres of wood per capita. That is around 3 tonnes or 45 GJ per person annually.

This seems rather on the high side, especially when some Nepalese households were managing with 6 cubic metres per HOUSEHOLD.

Also, some plants produce biomass in great abundance - Miscanthus and similar grasses will produce 25 tonnes per hectare annually of dry matter in many parts of the world, so 3 tonnes per capita would only require 1200 sq m of land per capita, a growing area for a planet of 10 billion people of only 12 million square kilometers, 10% of what you were considering.

Improve the efficiency of the processes (self-heating houses, efficient stoves, TEG generators for lighting, for example) and probably 10% of this fuel use is all that would be required.

kris de decker



"Telling us that the wildfires which are causing many problems in Australia - and they are certainly a serious threat to life - are more damaging to humans than the use of controlled domestic fires does not seem to have good evidence."

The Australian wildfires are just one example. And there will be more examples each year. We ain't seen nothing yet.



Would you consider writing an article on compost based heating systems?

Although some systems depend on industrial wood chippers, these wood chippers could be powered by biogas produced inside the compost pile (see Jean Pain's work: https://www.dropbox.com/sh/7j32pgllmomdfew/AADo5-559B4lJyf9EFWqM8FRa?dl=0&preview=Another+Kind+of+Garden.pdf ).

A low tech wood chipper would also be welcome.

Assuming the pile is made for compost, this form of energy could be considered as carbon negative that also contributes to the regeneration of stripped-from-fertility soils.

Some more sources that may help for such an article are:


 J Kovatch


I doubt the calculation of 80% of the earth surface being needed for wood production. The paper industry has perfected the hybrid poplar production and it is surely more efficient than the calculations allow. Last figures I remember are 2 acres will sustain a homestead at a 10 year harvest cycle, or 0.2 acres per year used. I think the big problem would be water for the trees, not the space required.



Thank you for this reflexion on the firewood topic, however there is a huge contradiction!

"so we need 12 billion ha or 120 million square kilometers of forest if we want to avoid deforestation. That’s three times as much as we have today, and about 80% of the total land area of our planet (150 million square kilometers). Because we don’t need extra space for factories and roads to make and distribute consumer goods, we actually could go back to the open hearth without destroying our environment."

How can you conclude this, when we would need 3 times more forest area?? & i guess this doesn't even account for the land required for food... What this says is that if we work with the existing area of forests, we might only make it for one third... 3.33 Billion people.

...or did i get this wrong ? how ?




Have you looked at microgasification? It essentially eliminates indoor air pollution from cooking and the byproduct(biochar) can actually be used in reforestation, not deforestation.



You do not need 6 cubic meter. We use around 10 max here for 3 people and our house is way too big for us.
With good insulation, large household and intelligent management, my guess is that you would use much less.

It is also not true that fire is very polluting. Most people do not know how to light a fire and go on burning wood at low temperature and polute. They are usually buying wood cut in large pieces that burn inefficiently and are too lazy to spend some time collecting small firewood to get an initial high temperature. If you look at old peasant in cold countries, they spend a lot of time splitting wood in small pieces to get a good fire going on (and fast). They also use extra dry wood and the more you split in advance, the drier it gets.

Even for an open fire, I am spliting all 50 cm long logs in two or three thin piece and put them in a pyramid shape to get a "torching" firewood. The base of the log touching hot amber, turns into gaz (fume) and this smoke trapped between the log and the wall burns at the top of the log. Besides, when you put a new log, water is escaping at the top (you hear a pssshit and see bubbles), whereas in the horizontal mode, it is mixing with combustion gaz and lowers efficiency.

I get a real powerfull torch for hours and I guess i am well above the 15 percent "theoritical" efficiency of open fire, because it actually get pretty warm in the room, even if it is zero outside. I guessed people found a lot of tricks, playing with fire on a daily base and would probably not all live in toxic fumes.

Chimney design is also crucial. Here they do not let smoke comin into the room if you burn like I do.

Joshua Spodek


The section "Energy Use Compared: Ancient vs. Modern Households" made me think of my food power consumption. It was December and I don't heat my apartment so it's chilly.

Yet my refrigerator was on. As I started to wonder if I could get by without it, at least during the winter, when the apartment is cool anyway and my food is less perishable -- more root vegetables, cabbage, etc -- I figured the best way to find out was to try. Nothing would kill me and I'd find the problems to solve best by exposing and facing them.

So I unplugged the fridge, ate the perishable things, and will see how long I can go before plugging it back in. Putting things by the window, where it's cooler, is working so far.

I think Low Tech Magazine started me fermenting things instead of refrigerating . . . [searches site] . . . yes, these posts:



So I already have a bunch of sauerkraut and vinegar. Let's see what comes next. I also look forward to my electrical bill.



Intresting article! It's not like heat from electronic stove, other appliances disappear, it stays in the house. If heating system uses termostat than it doesn't use more energy. At warm period of the year people tend to avoid unnecessary heating. Clothes can be dried as easily with central heating as well from the same fire that was used to create electricity. Biomasas has to be harvested as well - sure it is not as energy intensive as mining copper or cobalt.

It is right on point that we need to stop overusing resources on disposable products, optimize the whole system if we want to live as easy as we are able to do now for many years to come.

Simon Derauw


Dear Kris,

I quite not understand when you considerate sustainable to have about 80% of the total land area of our planet reforested in order to supply fire combustion for 10 billion people. Obviously, we are far from having that space available considering the land use of 10 billion people.

Kind regards,

Bruce Teakle


Thanks Kris for another excellent article.

I live in Australia and a lot of my time is spent managing native forest on private land, with a big focus on reducing the impact of wildfire on people's stuff and on ecological values - both of which are being devastated by our current season of wildfire on top of drought.

Climate change is making bushfires much worse, but this comes on top of 100 - 200 years of white-fella management (or non-management) of our forests. Aboriginal fires - cool and frequent - reduced understorey vegetation and enabled trees to grow old and big.

Thickened understoreys and infrequent fire leads to much hotter fires, killing tall trees, burning down hollow trees and leading to shorter, hotter-burning regeneration.

Stepping back our sick and overcrowded forests to a more Aboriginal structure is complex: often you can't simply burn it into shape. It takes lots of cutting and fuel disposal to re-structure the forest without incinerating it.

I have a constant struggle working out how to dispose of surplus wood fuel without causing more forest and soil damage. We use wood to cook in our own home, make charcoal for cooking and blacksmithing, make biochar for gardens and orchards and make things out of wood - but this takes a lot of labour and processes relatively tiny amounts of waste wood.

This means that a lot of energy wood could be produced as a by-product of managing forests for ecological values. If it's burnt in the communities that are in the forest, minimal energy is required for harvesting and transport, and the ash and char waste can be returned to the land that produced the wood.

Will wood produced this way sustain the affluent lifestyles of our wealthy cities? Of course not - could anything?



Dear Kris,

Thank you for this article. It would be usefull I think to mention "new" stove designs based on Aprovecho Research Center's rocket stove. This design manages to produce high energy with much less fuel and almost no smoke thanks to complete combustion. Those stoves are among those promoted by the Clean Coocking Alliance (https://www.cleancookingalliance.org/home/index.html)
Well designed rocket stoves work so well that they now epitomize low-tech for me.



While I agree with the point made in the article: the under-appreciation and usefulness of a fireplace, using forest fires in Australia as an example of climate change weakens it. Forest fires are a natural occurrence in most of Australia and other dry regions of the world. Many plants have evolved to survive and thrive with fire, so-called pyrophyte plants. Some species like Eucalyptus have deliberately evolved to be flammable, and many species of pine have seeds that only germinate after being exposed to high temperatures.
Large scale forest fires neither are a new phenomenon, nor are the recent temperatures any extremer than those measured prior to 1910. Which is the reason for media and researchers not to include older temperature records as it would show no upward trend for Australia, but more of a 'business as usual' scenario.

David Veale


Don't forget the important byproduct of a wood fire -- ash! We both heat and cook over wood in our Michigan home, and I also use the ash for fertilizing our orchard and garden (it's the original "potash", high in calcium and potassium for sweetening acidic soils), dehairing hides as part of the leather tanning process, and also for creating lye used in soap making. It's precious stuff -- and even with our extensive use (about 6 cords per year), we generate less than 100 gallons of it annually.

kris de decker


@ Marnix (#14)

I read very different things about the reasons not to include temperature recordings from before 1910: https://theconversation.com/factcheck-was-the-1896-heatwave-wiped-from-the-record-33742

David Veale


@Marnix -- as a forester I studied wildland fires quite a bit, as well as having fought them. The key here is the fire return interval. Most all forests have a typical interval (in Washington State, USA where I worked, it was 500 years on the wet side of the Cascades, and somewhere between 5-30 years on the dry eastern side of the mountains). If the fire return interval becomes too frequent, forests cannot establish -- assuming there's still enough precipitation (typically 25cm annually, where it doesn't all evaporate too quickly) for them to establish. I strongly suspect that many Australian forests are seeing a significant increase in fire frequency combined with a drop in average available soil moisture -- just as we're seeing develop in California and many subtropical environments.



One point that makes the claims less straight forward: What about flexibility? It is rather rare being in need of all the opportunities an open fire delivers. So the consequence is a huge drop in efficiency by firing up each time you just need a coffee. At the same time you cannot stop one effect from another, so light will always mean heating, if you have overheaten, you need to waste all the energy by getting rid of it somehow.
Our ancestors logic, third world economy and your calculation are based on very specific conditions that are just not to be found in our grown-up societies.
Conditions are: small-crowded living spaces, constant huge heat loss, cheap broadly available fuel, low purchasing power, small complexity overpowers specialisation, not constricted time windows



Interesting article, but the debate is obviously not closed.

I live on the southern slope of Massif central, at 500 m above sea level. It gets reasonably cold in the winter with several nights under -5 degree celsius.
I have an open fire in the kitchen (because i have very low income and little time to rebuild the place) and a cast iron stove in one room.
Living in the kitchen during december and january is tough. It usually gets under 8 degree and every task becomes painful (for the fingers...).
You would not be able to have a sedentary job at this temperature. These houses were build by farmers in the 19th, tough people who worked outside as much as they could...

I usually burn between 10 and 15 "stere" (french measure) of hard wood for both stove and open hearth. It correspond to 7 m3, for four.
In the room, with a small stove, we have 18 degree in average (22 in the evening, less in the morning) and my partner does office work at home. The stove is simple but efficient.

However, there are advantages and disadvantages: with experience, i came to be able to make a very warm fire, nearly smoke free, in a matter of minute in an open fire place. Impossible to get the same effect with a stove if you get home wet and shivering after a cold rain.

Ancient people would have found stove inconvenient because, to have a small stove burning nice and warm you need a lot more work on your wood (sawing and splitting), whereas you can burn larger piece in an open fire. If you do not have expensive machines to make the wood fuel, you'll find it is tough. Noone can tell if those complex machines that usually run together with tractors and thus need petroleum, will be massively available un the long term. I doubt it.

Ancestors were smart. If it is hard to warm a large room with a simple fire, they had a trick: they were building reflecting walls
It you sit in between the walls, then it is warm.
I started to insulate the ceiling with raw wool for some years, and the temperature have gone up quite a bit.

To make a smoke free fire, I usually try to cover the burning center with wood, so that it radiate back to the center. In this way it gets really hot, with a lot of red amber, and it then burn long dried wood (i split logs)positioned verticaly against the wall. In the end one can put large logs against the hearth (not in the hearth)and get large flames and no smoke.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been saved. Comments are moderated and will not appear until approved by the author. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Comments are moderated, and will not appear until the author has approved them.

Your Information

(Name is required. Email address will not be displayed with the comment.)