Detect
We use satellite imagery and multispectral analysis to map where Prosopis is growing across the district and to estimate how much biomass each plot will give.
Artisan Biochar
We give village artisans a simple steel kiln and a clear method, and together we turn invasive Prosopis juliflora into biochar that holds its carbon in the soil for centuries. Every batch is recorded as it is made, so the carbon it stores can be certified and sold as credits under the Global Artisan C-Sink methodology.
The Kari Kontikki Kiln, which we build in Coimbatore from 10 mm steel and rate for firing at up to 700 °C.
01 — The Kontikki kiln
A cone of steel that burns its own smoke
The Kontikki is our open-top conical kiln, which we fabricate from 10 mm steel at our own carbon machinery unit in Coimbatore. It works on the flame-curtain principle that the Global Artisan C-Sink guidelines recognise for artisanal biochar. The artisan feeds it in thin layers onto a glowing bed, the gases from each new layer catch fire across the mouth of the cone, and the char settling below matures at up to 700 °C, which is the range in which biochar carbon becomes most stable.
This is what happens inside the kiln while it is firing.
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01 / GEOMETRY
Technical specifications
10mm steel
- Mouth diameter
- 6.5 ft (≈ 1.98 m)
- Lower base diameter
- 3 ft (≈ 0.91 m)
- Height
- 5 ft (≈ 1.52 m)
- Material
- 10 mm steel
- Features
- Heat barrier, rotatable dumping lever, support stand
01 — The Kontikki kiln
The flame becomes the curtain
When charcoal is made the traditional way, in an earth mound, the gases coming off the wood leak out for days as thick, choking smoke. In the Kontikki, those same gases rise into the flame curtain and burn within minutes, so their energy goes into heating the next layer and the air around the kiln stays much cleaner for the people working beside it.
The bigger gain is where the carbon ends up. Prosopis that is burned in the open or sold as firewood puts its carbon back into the atmosphere within months. When the same wood goes through the Kontikki, about three-quarters of the carbon in the char is expected to stay in the soil for at least a hundred years.
What field measurements show
Grams per kilogram of char
Carbon monoxide
85% lessVolatile organic compounds
89% lessMethane, counted honestly
These figures come from Cornelissen et al. (2016), Emissions and char quality of flame-curtain “Kon Tiki” kilns for farmer-scale charcoal/biochar production, PLoS ONE 11(5): e0154617. Each pair of bars is drawn to its own scale.
C-Sink carbon credits
From a single batch to a certified carbon sink.
Every artisan takes the C-Sink training and passes its exam, and we register each kiln with its exact surface area and depth so that the volume of every batch can be worked out.
During each firing the artisan uses the app to log the feedstock and the amount of char, and takes dated, location-stamped photos and GPS video halfway through and again at the end.
A laboratory tests the char for its carbon content and its H/C ratio, which together tell us how much of that carbon will still be there in a hundred years.
The biochar is enriched and worked into farm soil or mixed into compost, and we track it from the kiln all the way to the field where its carbon comes to rest.
We offset the methane released during firing, as the guidelines require, and an independent certifier audits the batch records and the laboratory results.
The verified tonnes of CO2e are entered in the registry as certificates, which companies can then buy and retire against their climate targets.
KARI / BATCH RECORD
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CHAIN OF CUSTODY / STEP 01Train and register
Every artisan takes the C-Sink training and passes its exam, and we register each kiln with its exact surface area and depth so that the volume of every batch can be worked out.
How a tonne of biochar becomes credits
01 / BIOCHAR1 t
of biochar comes out of the kiln.
02 / CARBON75%
of it is carbon, less a 3% safety margin.
03 / CONVERSION3.67
tonnes of CO₂ match each tonne of carbon.
04 / RETENTION74%
of that carbon is still stored after 100 years.
CERTIFIED LASTING SINK≈ 1.97 t
of CO₂e is certified as a lasting sink.
This is the Global Artisan C-Sink worked example for Kon-Tiki biochar made above 650 °C with H/C below 0.4. Each project’s certified figure depends on laboratory analysis of its own feedstock.
04 / ONGOING PROJECT IN TENKASI DISTRICT
From invasive thicket
to soil carbon.
In Tenkasi, we identify Prosopis juliflora—locally known as seemai karuvelam—using satellite imagery and multispectral analysis. Village artisans harvest it and make biochar in Kontikki kilns. The biochar goes into farm soils, with every batch on record.
01 / 05Detect
Harvest
Village teams clear the mapped stands, cut the stems to a size that fits the kiln and leave them to dry so that they burn cleanly.
Carbonise
Artisans tend the Kontikki through the day and turn a tonne of Prosopis into 350 kg of biochar.
Lock in permanence
Once it is quenched and enriched, the biochar is worked into farm soils, where its carbon stays put for centuries.
Verify
Every batch is documented through dMRV, and we keep watching the cleared land from space for any regrowth and for native plants coming back.
Where the tonne goes
A day at one Kontikki
1,000 kg
of Prosopis goes into the kiln each day.
350 kg
comes out as biochar, which is a yield of 35%.
650 kg
leaves as water vapour and as gases that burn off in the flame curtain.
05 — Impact
What one kiln delivers in a year
These are indicative figures for a single Kontikki working 300 days a year at the Tenkasi rate of a tonne of Prosopis a day. Every new kiln that a district or an offtake partner brings into the programme adds another set of them.
Six goals served by one value chain
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Zero Hunger
Biochar helps smallholder soils hold on to water and nutrients, and it builds a healthier soil structure over the years.
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Good Health and Well-being
The flame curtain burns off most of the carbon monoxide and volatile organics, so people living and working near the kiln breathe far cleaner air.
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Decent Work and Economic Growth
Trained village artisans earn a living through the year from harvesting the wood, running the kilns and applying the biochar.
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Responsible Consumption and Production
Wood cleared from invasive stands finds a second life as a durable product inside a circular value chain.
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Climate Action
Every batch takes carbon out of circulation and stores it for centuries, with C-Sink verification standing behind it.
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Life on Land
Clearing Prosopis directly supports target 15.8 on invasive alien species and frees the land for native restoration.
Collaborate
Durable removals, secured through offtake
When a company signs a forward offtake with us, it gets a steady supply of verified, long-lasting carbon removals from a project its people can visit, measure and explain to others. That commitment is what puts kilns and artisan crews to work from the very first season, and every certificate retired in the company's name leads back to a documented batch, a cleared stand of Prosopis and a farm where the carbon now rests.
If you run an agri-business or a plantation, you can also buy the biochar itself for your own soil programmes and pair that physical supply with certified removals.
07 — For Tamil Nadu
Tamil Nadu has made clearing invasive plants a statewide priority through its Policy on Invasive Plants and Ecological Restoration. In March 2026 the Madras High Court went further and set out a framework for removing seemai karuvelam that encourages district-level enterprises, public-private partnerships and self-help groups to put the cleared wood to good use. Artisan biochar gives that wood its most valuable use, turning what used to be a clearance cost into carbon revenue, rural income and restored land.
Carbon and biochar revenue cover part of the cost of clearing every hectare, so district and conservation budgets go further.
Satellite maps and batch records give district administrations a clear, checkable account of how many hectares have been cleared, how much wood has been converted and whether the Prosopis is growing back.
Artisan crews and self-help groups earn from every batch, and restoration becomes a rural business in its own right.
Cleared plots are handed back for native planting, and the biochar-enriched soil gives young saplings a stronger start.