Keeping the Door Open (and the Curtain Closed!): Why New Kon-Tiki Research Matters for Smallholder Farmers

This article was contributed by IBI member Carbon Standards International.

Smallholder farmers are the original biochar producers.

Long before carbon markets existed, communities across the Global South were converting crop residues into biochar using open-topped kilns, flame curtain pits, and simple pyrolysis vessels. The Kon-Tiki kiln formalised and refined that tradition — and the Global Artisan C-Sink Standard turned it into a pathway to carbon market participation for some of the world’s smallest-scale producers.

But standards are only as good as the science behind them. New research published in GCB Bioenergy by the Ithaka Institute now gives that standard something it has long needed: rigorous, field-relevant emissions data covering a wide range of feedstocks and real-world moisture conditions.

The study conducted the first direct, side-by-side comparison of greenhouse gas emissions from Kon-Tiki pyrolysis and open burning of crop residues – the practice it most commonly replaces. Five feedstocks were tested across dry, semi-moist, and moist conditions: wheat straw, orchard pruning, giant reed, coffee stem wood, and guadua bamboo. Emissions of CO₂, CO, methane, and propane were continuously measured throughout each burn. The result is one of the most comprehensive emissions dataset for flame curtain pyrolysis yet produced.

Compared to open burning, Kon-Tiki pyrolysis reduced CO emissions by around 35% and methane by 36% on average. For wheat straw – among the most widely burned crop residues globally – the reduction was statistically significant and large. Crucially, every tonne of straw pyrolysed produced around 200 kg of biochar representing a carbon sink of more than 500 kg CO₂ equivalent when applied to soil. The climate arithmetic strongly favours the kiln.

The key finding is the relationship between feedstock moisture and methane
emissions. Dry feedstocks at or below 15% moisture produced consistently low
methane – below 5 g per kg of biochar – regardless of feedstock type. Wet feedstocks at or above 25% moisture produced up to ten times more. This confirms the importance of the Global Artisan C-Sink Standard’s existing 25% moisture threshold, while making a strong case for differentiating emission factors by moisture class so that producers who dry their feedstock further are credited accordingly.

The mechanism matters for understanding what farmers can actually control: wet biomass absorbs heat during combustion to evaporate water, cooling the flame curtain and allowing methane to escape unoxidised. Drying feedstock before use is a simple, low-cost intervention – and one the Global Artisan C-Sink Standard already supports with a dedicated drying protocol. This research gives that protocol even stronger scientific foundation.

These findings are significant for farmers. The stronger and more credible the
emissions case for Kon-Tiki pyrolysis, the more confidently certifiers, buyers, and regulators can support artisan biochar credits. Robust science is what keeps smallholder participation viable in markets that are increasingly scrutinised.

As we know, smallholder farmers are not peripheral to climate action. They manage vast areas of agricultural land, produce enormous quantities of crop residues, and are often the first communities to bear the costs of a changing climate. Research like this – precise, practical and directly actionable – provides the differentiated, evidence-based emission factors that will allow the Global Artisan C-Sink Standard to remain both rigorous and genuinely accessible, ensuring that the farmers most essential to scaling decentralised carbon removal can continue to play a central role in addressing climate change.

Lotz, S., Hagemann, N., Hölscher, D., & Schmidt, H.-P. (2026). Methane Emissions From Flame Curtain Pyrolysis (Kon-Tiki). GCB Bioenergy, 18, e70108. https://doi.org/10.1111/gcbb.70108