What kiln temperature records does a biochar verifier ask for?
Under Verra VM0044 v1.2, production temperature is logged continuously by an instrument with a recordable signal, such as a thermocouple, and averaged for the year. The sensor is calibrated against a primary device from an independent accredited lab. Without a measured temperature, a default factor of 0.56 applies and credits drop.
Why temperature changes the credit
For biochar in soil, VM0044 v1.2 sets how much carbon counts as lasting 100 years by production temperature: 0.89 above 600 °C, 0.80 from 450 to 600 °C and 0.65 from 350 to 450 °C. Where temperature is not measured, recorded and reported, the factor is 0.56.
What the log must show
- A continuous record, rolled up to an annual average.
- A digital or analogue instrument that records its signal, such as a thermocouple or thermoresistor.
- Calibration against a primary device from an independent accredited lab, as often as the maker specifies.
- Written operation and maintenance logs.
- An offsite electronic backup of all logged data, with access for the verifier.
High technology status needs it too
A facility counts as high technology only if pyrolysis gases are recovered or burnt, at least 70% of the pyrolysis heat is used, pollution controls meet emission limits, and production temperature is measured and reported. Only high technology biochar can go into concrete, asphalt and other non-soil uses.
Is there a minimum temperature?
VM0044 v1.2 sets no minimum temperature as an eligibility condition. Its permanence table starts at 350 °C, with lower factors for cooler bands. A project can choose a stricter floor, such as 450 °C, to keep every batch in the medium band.
Example: the same biochar, logged and not logged
- Carbon stored in the biochar before the permanence factor: 100 tonnes CO2
- Kiln logged between 450 and 600 °C: 100 x 0.80 = 80 tonnes counted
- Kiln not measured: 100 x 0.56 = 56 tonnes counted
- Project emissions from fuel and transport are deducted after this
Factors from VM0044 v1.2, Table 3 and footnote 21. The 100 tonnes is an example figure.
What Senseible does here
On a Senseible project, kiln sensor temperature logs keep each batch's heat record with its lab result, and the automatic flags with kiln at least 450 C, H:Corg at most 0.7, spreading inside the plot and transport distance catch a cold batch on the spot. Senseible prepares and checks the record; an accredited verifier checks it again.
Last reviewed 2026-11-02.