On Biochar

23 05 2017

Last weekend, as the threat of looming downpours for much of Tasmania was forecast, I went to a biochar workshop organised by the Huon Producers’ Network, and I reckon it was the best thirty five bucks I ever spent……. I’ve read quite a bit on the matter, and have always been fascinated by Terra Preta. Having cut down some fifty trees to make way and building material for our new house, I’m not exactly short of biomass to get rid of…. I had four huge piles of the stuff, and unfortunately, sometimes even the best laid plans have to yield to reality and two of them have been burned to make way for ‘development’ on the Fanny Farm. Each time I burned the piles, I got the guilts knowing all that resource was going to waste and contributing to climate change, but having inadvertently put several tonnes of wood in the wrong place (designing my patch is an evolutionary process) and having no quick means of moving them, I just put a match to it. At least, the ash went on the current market garden patch……Image result for biochar kiln

I had some expectations of what I was going to be shown, but they were all thrown out the window…. I had been expecting to see kilns such as the one at right which are all enclosed for the purpose of starving the fire of Oxygen so as to pyrolise the wood and make charcoal. My friend Bruce in Queensland has been making charcoal this way for thirty years to satisfy his blacksmithing habit (and those of many others I might add), and he has this down to a fine art. But it appears there’s a revolution underway…..

The presenter on the day was Frank Strie, who thirty years ago emigrated from Germany with his whole family to Tasmania. “We started to plant lots of different fruit trees” Frank says on his website, “such as Cherries, Apricots, Peaches, Plums, Prunes and various apple and pear trees. And of course, we wanted to grow our own vegetables. Also, about 20 years ago we established a Hazelnut Orchard, which covers nearly one third of the property.” It’s all organic of course, and he sounds like he’s pretty good mates with Peter Cundall, Tassie’s gardening guru…… See his Terra Preta website.


“The baby”

The fact that he brought three kilns on a trailer and the back of a ute all the way from Launceston just shows how versatile and portable his gear is.

The new kilns are open topped, and most interestingly, funnel shaped. They make the process faster – like maybe half the time or better – and allow for activation of the charcoal (which is what turns it into biochar) all in one go. Being able to just tip the finished product onto the ground instead of laboriously shoveling it out of the kiln looks good to this old man with a bad back as well.

Andrew, a local also known as Stretch – and so tall he can’t fit in photos – was also there to ably assist Frank; he’d organised20170520_121304 lots of firewood and stacked it in piles of graded sizes along with cardboard and kindling. We actually got three kilns started; from a smallish one designed for hobby gardeners, to something that will make a cubic metre at a time (and double up as a BBQ!) to the farm sized device I could probably use but can’t afford….. though there is now talk of buying one as a community resource which is a darn good idea!

The idea of the funnel shape is that as the air outside is heated, it rises up the sides, and when it reaches the lip, a vortex effect is created causing the air to be sucked into the kiln speeding up the burn. The ‘big one’ even comes with a skirt that acts as a venturi, speeding up the air as it is squeezed between the kiln and skirt at the lip of the kiln. The effect was clearly visible, though nigh impossible to catch in a still photo.


The ‘smothering’ effect is created by simply adding more and more firewood to the pile. Before combustion is complete, the fire is quenched (with water on this particular day, but normally a liquid fertiliser would be used) from the bottom up. The bottom of the kiln is plumbed to a pipe which can be used for both removing excess liquid, or adding it under pressure from an IBC on, say, the back of a ute. On the day, Frank used a garden hose, because we could not do what he normally does because of where we were….



On the day, the kiln was not filled to capacity due to location and time constraints, but you can clearly see the results. The big kiln even comes with a winch to tip the biochar out for easy work, and if it wasn’t for the fact I’m far too busy house building and counting my remaining pennies, I would buy one tomorrow,

To learn more about biochar, here is an interesting link supplied by Frank that anyone keen on this process would find enlightening. I think this is definitely the way of the future, a bright light among all the rubbish we see every day about renewable energy and electric cars. This has the potential to sequester huge amounts of Carbon, and even more importantly, prepare farm soil for the post oil era looming on the horizon.




15 responses

23 05 2017

Mike said: “Each time I burned the piles, I got the guilts knowing all that resource was going to waste and contributing to climate change”.

My understanding has always been that – with regard to CO2 outputs – if you are simply ‘converting’ carbon that is already in the biosphere from one form to another then you are not contributing to climate change. You are simply participating in what is essentially a naturally occurring climate cycle. I acknowledge the potential impacts of ‘extreme’ levels of such processes of ‘conversion’, but isn’t it ‘fossil carbon’ – releasing the stuff locked away for millennia – that we should ‘get the guilts’ about…

23 05 2017

Only if you replace the cut down trees……. and I am working on that.

23 05 2017
Barry Vokes

I’m happy that you posted this Mike. As a Texas Master Gardener (and current president of our county Master Gardener Association), I’m interested in biochar. I did considerable research on this several years ago and have written newsletter stories about it. Biochar passes the tests of time and history and there is some evidence (in South America) that it actually regenerates itself and grows over time. While I’m knowledgable about biochar, your post added something new and interesting to me — the specific method your friend and colleague uses to create it. The old-fashioned way can get a bit tedious. I’m especially interested in the comment that the technique you describe both creates and activates the biochar. That intrigues me. As for your regret about burning that pile of accumulated timber and brush, just remember that the average person does not know the difference between carbon sequestration and carbon de-sequestration. Keep your sense of humor. I suspect you will need it one of these days. We all will. There will be some surprises along the way.

23 05 2017

Biochar is a spin off of terra prete, which was discovered in the Amazon basin relatively recently, created by people hundreds of years ago. Be interesting to find out if outside the Amazon it can regenerate itself. We sure need it in this nation of poor soils. Rock dust is another useful soil conditioner.

23 05 2017


Super cool. I think i will tap into that one.

I would want to include

1. BBQ
2. Some way of heating water for the outdoor bath.



24 05 2017

Yes, he did mention heating water….

24 05 2017
Bruce Teakle

Thanks for your biochar post Mike! Very interesting – I especially like the look of the big tilting cone kiln. Can you ask Frank why he quenches the char with water, instead of putting on a lid? We make quite a lot of biochar/charcoal in 200 litre drums as well as a big steel box, and snuff the charcoal by restricting air, so we don’t need to get water to the site (quite a challenge), don’t have to transport wet charcoal, and can use the charcoal for fuel as well. The easy way we make biochar is described in my blog: http://bruceteakle.blogspot.com.au/2017/01/quick-and-easy-biochar-in-200-litre-44.html
We also use charcoal as a fuel every day, in a Thai charcoal stove. Charcoal is an excellent, smokeless fuel which needs very little hardware and doesn’t blacken your pots: http://bruceteakle.blogspot.com.au/p/cooking-on-thai-charcoal-stove.html
I agree: we’re past the time when it’s fine to burn wood to waste in windrows. Fuel-grade wood can be used for fuel to displace fossil fuels, or used as biochar for soil improvement and long-term sequestration. That’s the economy we need to build asap.

24 05 2017

Hi Bruce….. he normally quenches it with liquid fertiliser. Water was used for the workshop because it was less expensive and easier on the day. Quenching is way faster, I’m told. We made all that charcoal in the pics in just four hours…. I also think the idea of doing it this way is that you make the biochar right where you need it so don’t have to transport it wet. Of course it means moving firewood instead!

24 05 2017

Interesting. Here’s a little something that I found (after reading your post) which I found just as interesting:


24 05 2017
Bruce Teakle

Interesting, Lemmiwinks, I read the “beware” essay. It reads somewhat like an Ian Plimer essay about climate change. Essentially it says that industrial scale agriculture for biochar could be harmful (agreed), clearing old growth forest for biochar isn’t good (agreed), some charcoal doesn’t last as long as others (agreed), sometimes biochar doesn’t increase crop yields (well documented), and making biochar risks de-oxygenating the planet (??!! eccentric proposition). (see http://www.columbia.edu/cu/21stC/issue-2.1/broecker.htm). The essay cherry-picks fragments of evidence and neglects to take an overview.
Consider the load of biochar we made here today: a 200litre drum full, made mostly from lantana. The oxygen and hydrogen from the wood has been put into the atmosphere as water, leaving some of the carbon to go in the soil for 100s or 1000s of years. If we didn’t char it, all the oxygen, hydrogen and carbon from the wood would be in the air, in the form of CO2 and water, within months, from normal decomposition. The charcoal will make a small area of heavy clay soil more friable, and more able to absorb water and nutrients. It’s the same with other piles of sticks we make into biochar: if we don’t, they’ll either rot or be burnt, releasing all the carbon as CO2 in short time.
Sure, biochar shouldn’t be a religion, and it requires the same caution as any other land and ecosystem management should. But it is a useful technology as part of a systems approach to our problems.

25 05 2017
Frank Strie - Terra Preta Developments

In short: Spot on!
Considering when the Biofuel Watch claims first surfaced years ago, many credible, responsible, knowledgeable people have commented on these often conflicting arguments. There is plenty of information out there what we aim for. The Biochar Journal has valuable information for anyone truly interested in the truth and facts.
Thanks for the great discussions and comments.
Good work in progress.

24 05 2017

This is over the top…….. Oxygen depletion….? REALLY? Give me a break; air is 200,000ppm O2. Compare that with 400ppm CO2…… We’re not going to run out any time soon. And nobody is talking about cutting down forests to make biochar, there is so much wood litter on the side of the road here where I live, and sawmill offcuts, I could, given enough time, cover my whole farm with enough biochar to make it worthwhile without cutting down a single tree……

25 05 2017

Chaps, I thought the oxygen depletion was wacky and detracted from an otherwise OK article.

25 05 2017

Ah good……. 🙂

7 07 2017

It may be worthwhile reading up on the original archeological research re. Terra Prete (National Geo has some good articles online). TP is not the same as the biochar we can produce as per Mike’s post. It also includes a host of other inputs including human, animal and food wastes and a bacterial load that may well take many years to develop. There appear to be a number of factors which ‘activate’ it to varying degrees – all are probably important to the overall equation. In other words, ‘it’s complex’! Which is not to say it shouldn’t be pursued of course. I guess though we may be wise to temper any notions that it might ‘save’ Australia’s depleted sold, our broad-acre agriculture and a population of 20-30M given that – over the several millennia it took to develop in the Amazon it appears to have supported a population of no more than 500,000!

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