This series of blog posts and videos will follow my experience getting stuck into the physical realities of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More production, building and honing a number of burner retort systems, assessing different feedstocks and pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More efficiencies. I have been a biochar enthusiast since being introduced to it during my MSc (in Environmental Change and International Development), and I, like many others it seems, became fascinated with the concept. Through these past years, however, I have become increasingly concerned about the industry’s fascination with research over implementation. There are numerous extremely valuable papers that explore the various characteristics of different feedstocks, as well as their uses in specific soils, systems, and geographies; yet there is a significant deficiency in publications on the logistics, economics, and general realities of biochar application and production. 

It is nearly unanimous now that biochar is a serious game changer in the battle against climate change, soil degradation, and food insecurity; so let’s focus on getting biochar, or (perhaps better) the means of producing it, into the hands of those that need it most.

Choosing the Right Burner Setup

There’s no shortage of designs out there—from Kon-Tiki kilns and flame cap pits to TLUDs (Top-Lit Updraft) and double-barrel retorts. I opted to begin with a double barrel burner retort, after watching Living Web Farms brilliant biochar series on YouTube. The double barrel system appealed to me because of its hypothetical efficiency, low greenhouse gas emissions output and the notion that it can self-regulate its own burn, utilising the feedstock’s natural gases. 

A small retort system, at its core, is just a sealed container that heats biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More in the absence of oxygen, releasing volatile gases that either combust or vent, depending on the setup. Getting the seal right is crucial, and that’s where many DIY systems fail. Leaks lead to inefficient burns and unnecessary emissions, not to mention fire hazards. I went through a few iterations before I could comfortably say my setup was safe and effective enough to run reliably. 

It is important to note that clip-lid (or open-head) barrels can be more effective than standard oil drums, which often use nozzle/tap holes instead. I purchased a scrap barrel like this to use as a single drum (smother) burner by angle grinding the top off, which is effective at producing charcoalCharcoal is a black, brittle, and porous material produced by heating wood or other organic substances in a low-oxygen environment. It is primarily used as a fuel source for cooking and heating.   More, but is far more wasteful than the other systems. 

Another key consideration is hole sizes – I drilled my air-intake/gas-release holes with a 20mm hole saw bit, and I am concerned, after initial burns, that this may be too large, allowing natural gas to release too quickly and oxygen to be too available to the primary burn fuel, resulting in an incomplete burn. 

The cost of creating one of these burner retorts will vary depending on your location and access to scrap metal. Having not been in the world of fabricating metal, I was concerned that I would have lost a small fortune on this burner, but the reality was far more reasonable.

Approximate costs:

Thoughts Going Forward

The biggest lesson so far has been that biochar production, in its most practical form, is as much art as science. You can read combustion temperature charts and efficiency curves all day long, but you don’t really get it until you’re chopping up feedstockFeedstock refers to the raw organic material used to produce biochar. This can include a wide range of materials, such as wood chips, agricultural residues, and animal manure. More, listening to the roar of the flame, and watching the retort sweat under heat.

It’s this kind of visceral learning that I think is missing from much of the discourse around biochar. The lab data is invaluable, but implementation (especially in low-resource contexts, where we expect biochar to have the most impact) demands a level of improvisation, responsiveness, and embodied knowledge that only hands-on practice can provide.

As I continue to refine these systems, I’m beginning to think less about producing perfect char and more about understanding how biochar systems can be replicable, affordable, and adaptable in a range of contexts. This means embracing imperfection and sharing what doesn’t work just as freely as what does. Stay tuned for plenty of that!

Ultimately, the goal isn’t just carbon sequestration or soil regeneration – it’s agency. If someone in a rural community, a smallholder farm, or an urban garden can take a pile of waste biomass and turn it into a climate solution with tools they understand and control, that’s a win. And it starts with people like us, getting our hands dirty, making mistakes, and lighting the match.