Adelaide Hills Biochar Initiative

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by Brian Lewis - September 25th, 2017

IMG_1439 Photo courtesy of Nicki van Hooff.

The Mt. Barker Community Garden recently welcomed me to their Duck Flat site to demonstrate making biochar using a Maccy Kon-Tiki flame-cap style kiln. We successfully made a barrow load of biochar from 5 (or what is it 6?) barrow loads of tree litter that would otherwise have been mulched using their power mulching machine. The biochar wil be used in their potting soil and also in the compost heaps that the garden manages.

Members were impressed with the ease and simplicity of this method of making biochar.


by Brian Lewis - July 7th, 2017

Extract from a letter from Tom Miles, Chairman, International Biochar Initiative, 7 July 2017.

Sustainable agriculture and soil fertility have been central to the terra preta/agrichar/biochar development since the beginning of the current development efforts (2003-2017). Carbon sequestration was much touted as a potential source of funding for biochar production and use but never the only focus. Just look at the literature and the discussions on this list.

In my company we started looking at biochar as a co-product of gasification in about 2003. We had heard about “terra preta” and we had had experience in the 1970s with the beneficial effect of charcoal on crops in poor soils in Central America, on our grass seed crops here in Oregon, and in the 1990s with charcoal as a component of potting media.
Nikolaus Foidl and others had shared their experiences with charcoal on this list and on the improved cooking stoves list.

In 2004 Danny Day held a conference at University of Georgia in which UGA reported on their work with biochar and seedlings. Dr. Makato Ogawa reported to that conference on the relationship of micro-organisms to charcoal and his extensive use of biochar to restore tree health in Japan.

IBI, then International Agrichar Initiative (IAI), was organized in 2006. Erich Knight, Ron Larson, and I started the terra preta email list in 2006 to support the IAI effort. The term “biochar” was coined by the late Peter Reed to replace “agrichar” which had been trademarked by a private company. A lot of this history is on the web.

In 2008-2012 IBI got a boost to develop biochar for carbon sequestration, thanks to the efforts of people like Stephen Joseph who were part of that process. About that time Europe and Australia also invested heavily in biochar research for soil fertility and carbon sequestration.

Recently biochar research and use has substantially increased in China and South Asia. Some of the research has been re-discovering how biochar has been used historically and how to apply it today. For example, charcoal had been used for many years as an essential element of seedling planting mixes by friends working in Central America. Other efforts have been on how biochar can be modified to enhance its properties.

Today, tens of thousands of tons of biochar are used for environmental remediation, soil fertility, and other uses.
Our challenges continue to be to match the different qualities of biochars with appropriate uses, and to learn how to take advantage of short and long term benefits.


by Brian Lewis - July 4th, 2017

On 30 June I finally used my new Maccy-Kontiki kiln to make biochar from my tree litter down in the meadow.

In progress

In progress

The following observations may be of interest:

1. Overnight rain had wetted the wood but the day was sunny and mild with only a slight breeze. So I did not bother with any wind shields.

2. I had no trouble lighting a fire in the bottom of the kiln with some dry twigs I had brought with me for the purpose plus some newspaper plus a firelighter!

3. After the process had started there was some light smoke but it dissipated quickly.

4. When the process was going well I noticed the flames seemed to want to rotate around the four sides of the kiln. I also noticed a build-up of ash over the burning wood. So I started worrying that the process was not happening as it should. I have since concluded that a characteristic of this process is that it needs to burn the surface layer of the wood in order to heat it sufficiently for the volatiles to escape and be burnt.

5. I noticed that the sides of the kiln have warped but no damage is yet apparent.

6. When the burning wood had reached almost to the top of the kiln I used the hose to quench the fire and filled the kiln with water. I had forgotten to put bricks under the kiln so drainage took longer than I had expected. Like overnight!

7. The next day I shovelled the char into a large bag placed in the wheelbarrow. And then I found I could not budge it! So I transferred the char into 3 smaller bags.

In progress

In progress

After quenching

After quenching

After bagging

After bagging

Conclusion: The quality of the char appears to be very good so my concerns about ashing have been allayed.

I have weighed the wet char and will weigh it again when dry and then report back here.


by Brian Lewis - June 9th, 2017

The first trial of my new Maccy-Kontiki Kiln took place last week and I can report that it was most successful.

It was a sunny still day but cold.
I started a small fire with paper and twigs and a firelighter in the bottom of the kiln which burned rapidly with some initial smoke.
I added small twigs for a few minutes and gradually increased size of twigs until I was adding sticks and branches.
Smoke mainly ceased and flames grew quite large and high (up to a metre and more at times).

When the kiln was about 1/3 full I ran out of large sticks.
Reverting to twigs caused a flare-up with smoke.

So I decided to quench the fire.

After quenching the kiln appeared about 1/4 full and there were some larger sticks that had not completely carbonised.
But on the whole the result was charcoal.

It produced about 1/2 a wheel barrow full.

I distributed most of it between 3 compost bins and gave my wife a bucket-full to play with.

I now have a Council permit to burn my wood heap so will use all three kilns down at the wood heap at the next opportunity and then report back.


by Brian Lewis - February 3rd, 2017

Date: 3 Feb 2017.
FROM: Tom Miles, The Chairman,
International Biochar Initiative

Compost & Biochar:
There are now several biochar amended compost products in retail garden stores. Biochar has been added to compost for filtration and growing media. Research continues to improve ways in which biochar can help compost, especially for water retention and odor management. Compost is used to reduce odor in poultry (broiler and layer) production. It is used to immobilize herbicides (e.g. clopyralid) in finished compost.

Compost 2017.
Biochar was well represented at the annual meeting of the US Composting Council ( in Los Angeles, California, January 23-27, 2017. There was considerable interest in how biochar could be used with compost for growing media, landscaping, stormwater filtration, and erosion control.

Organic recycling managers were interested to know how biochar could help recycle or reuse woody waste and biosolids.

Biochar producers, Phil Blom (Terra Char), Josiah Hunt (Pacific Biochar) and Michael Whitman (Blue Sky Biochar) spread the biochar message among the more than 90 exhibitors and 1080 visitors attending the conference.

IBI Chairman, Tom Miles, provided an overview of biochar production and use.

Jack Hoeck, Rexius Products, described how his company uses biochar to produce commercial potting soil and growing media (Opus Grows).

Dave Crohn, University of California, Riverside, described results from multi-year trials using compost, biochar and biosolids for managing water in turf.

Greg Stangl, Phoenix Energy, described their production of biochar and power as a solution to the excess wood in California.


by Brian Lewis - December 31st, 2016


The Kon-Tiki charcoal maker is a relatively new design of charcoal maker currently being adopted widely by the biochar fraternity. It is effectively an above ground open fire pit. The main advantages are simplicity of design, tolerance to shape and size of feedstock, and char volume potentially as large as the container volume itself.

The design of the Kon-Tiki is based on a truncated cone. Alternatively a truncated pyramid can be used. The following plans and parts list are based on the truncated pyramid version. This version has a capacity of 0.230 m³.


Assembly: Position all 4 side plates with 900 edge at ground level and lean in to form a truncated pyramid. Check that each top corner meets flush. Fully weld each side plate to its adjacent side plate. Position bottom plate and fully weld all around to the side plates.

Material thickness:

For economy and lightness a low gauge is desirable; but for durability a larger gauge is preferred. If a light gauge is used, say 1.8mm, then reinforcing rods welded to top and bottom edges would be recommended. These rods can be extended by 100mm at each side to provide lifting means.

For durability and ease of welding 3mm sheet steel is recommended.


Based on 3mm sheet steel the approx. weight of the unit will be 35 kg.

Based on 1.8mm sheet steel the approx. weight of the unit will be 21kg.

Rim shield:

In windy conditions it is desirable to use a rim shield. For a truncated pyramid the shield can be made from flat or corrugated sections of used roof or fencing iron placed on all 4 sides. Simply cut to height of unit (600mm) and stand on bricks or similar so that it projects about 100mm above the rim of the unit and about 100mm from edge. This will provide a route for the air to flow up the outside of the unit, be preheated on its way up along the outside and then spill over into the unit to provide an air vortex over and around the top of the flame-front.



Start a small fire in the bottom of the empty unit by constructing a small heap of twigs criss-crossed to form a “chimney” with an air space up the centre. Air will be drawn down to the perimeter of the fire and into the flame area.

Feed larger twigs onto the fire so as to build it up in size.

Continue this process, pausing only if the wood starts to smoke.

Larger pieces can be added as the flame area becomes larger.
What happens is that while the first top layer of wood is burning the layer beneath is heated to the point that it releases its gas which is burnt off cleanly at the top of the wood layer. Air cannot penetrate down below the top layer so no combustion can occur there. Thus the layers are progressively pyrolysed (heated in the absence of oxygen) to produce char.

Continue until the unit is full of char and no more new wood can be added.


When the feedstock has all been converted to char the char itself will then start to burn unless it is thoroughly quenched with water. I recommend that water simply be hosed onto the surface of the char and the unit filled with water. Alternatively the hot char can be tipped out onto a flat non-combustible surface and hosed down thoroughly.

A drain hole in the centre of the base of the unit will allow the water to self-drain when a channel is dug in the ground from the outside to the middle. The drain hole must be air sealed during operation so the unit should be operated while sitting squarely on the ground.

Any questions, comments or helpful suggestions please let me know.

Brian Lewis
Adelaide Hills Biochar Initiative


by Brian Lewis - December 17th, 2016

A new type of flame carboniser is being developed by the Warm Heart organisation that is shaping up to be an ideal approach for making biochar from tree litter. It does need to be tended (or stoked) to add new layers and prevent smoking
but the trough shape makes it very suitable for longish branches and prunings thereby reducing the need to cut to size as with smaller, drum-type carbonisers.

Go to:

to see an excellent description of the technique and detailed drawings and dimensions of the various models that they have designed.

I have added the above link to the blogroll for your convenience.


by Brian Lewis - November 18th, 2016

Now that the EPA has introduced its new air quality regulations the need for a safe and cheap alternative to burning tree litter is imperative. The answer has been staring us in the face for some years. Gasifier type biochar kilns can be used by households and home gardeners to cook their garden waste at high temperatures to make biochar. This can be done with a few minutes of wood smoke during start-up after which the waste emits a clean smoke-free gas flame. The end result is high carbon biochar for use as a soil supplement via the compost heap or by direct application. Biochar kilns need to be approved by Councils as a matter of urgency for use by home gardeners and landholders so that tree litter can be cleaned up progressively before the fire-ban season arrives.

Let’s get the Council wheels in motion on this so that by next year at the latest biochar kilns can be used throughout the Adelaide Hills to help dispose of tree litter in an environmentally friendly way.

I have spoken to the EPA officer responsible for the new air quality policy and it seems that Fire Prevention Officers at the Adelaide Hills Councils simply need to satisfy themselves that the kiln does not emit visible smoke to an extent that would contravene the intent of the new EPA regulations on air quality.

So on that basis the TLUD gasifier kilns and the Kon-Tiki kilns would all satisfy the requirements. Visible smoke and particulate emissions from these types of kilns are virtually zero within a few minutes of start-up. The wood gas emitted by the wood is burned off in a clean gas flame.

So anyone out there that needs to dispose of tree litter please consider making a simple gasifier kiln over the summer months and having it ready for use as soon as the fire-ban season ends.

I’m sure the various Council fire prevention officers would be delighted with any initiative that reduces the fuel load in such an environmentally friendly manner.

MAKING BIOCHAR – With Technical Manual

by Brian Lewis - November 13th, 2016

Making biochar - with Technical Manual

South Australian on-line publisher Strong & Bold Publishing has released a new publication entitled
“Making Biochar – With Technical Manual” written by ‘Yours Truly’.

This book is based on the experience gained from 5 years of developing and trialling 3 different styles of biochar kilns. It may be unique in that it includes detailed fabrication drawings for building two different types of kiln.
The book provides an excellent introduction to biochar basics and detailed instructions on the operation of a biochar kiln together with a chapter on the economics of making and selling biochar.
The pdf version of the book includes detailed drawings of two types of kiln. A case study on using a kiln by a commercial winery is included. And a description of a DIY kiln is also included.

The book is available to purchase for $9.99 direct from

This book will be of interest to all biochar enthusiasts, small landowners, horticulturalists and anyone else interested in the improvement of soils by the addition of carbon.

Strong & Bold Publishing specialises in e-publication of Australian writers, old and new.
Further enquiries may be made to:
Strong & Bold Publishing


by Brian Lewis - November 13th, 2016

Back when blacksmiths were still in business there were charcoal makers in and around Macclesfield who used the abundant timber resources of the area to make charcoal for the blacksmiths in the town and beyond. A local landmark by the name of Retort Hill is said to be the site of a charcoal making operation back in the 1860’s. (A retort is the technical term for a vessel designed to heat materials in order to purify them or distil other substances from them without actually burning them. So when wood was heated in the retort the moisture, tar and wood gas were driven off leaving behind only charcoal.)

Fast forward 150 years and Macclesfield is now the site of a small but progressive bio-charcoal making enterprise. It is called bio-charcoal or simply biochar these days because the emphasis now is on making charcoal for agricultural use AND to capture carbon rather than burning it as in days of yore.

Greg Marlu established SA Biochar Works near Macclesfield to concentrate on making biochar for use in the garden, either by applying it directly to the soil or by mixing it with compost.

Greg is an active supporter of the Adelaide Hills Biochar Initiative, having demonstrated how to make a gasifier kiln and shared his knowledge of how to operate the kiln safely and effectively at a working bee earlier this year.

I have seen the biochar making process in action at SA Biochar Works and have no hesitation in recommending their biochar for home garden use. I say this because Greg only uses wood waste, only waste from local timber, only uncontaminated timber, takes care not to allow smoke emissions during operation, and crushes the char to a consistent and small particle size amenable to soil application.

For further details on how to purchase biochar from Macclesfield go to:

Brian Lewis
Adelaide Hills Biochar Initiative