1. Convert wet feedstock to dry feedstock
Use moisture as a fraction of the mass received. With 2,250 t/year of wet feedstock and 43.5% moisture, the dry fraction is 56.5%. The annual dry feedstock is 2,250 × (1 − 0.435) = 1,271.25 t/year. The remaining 978.75 tonnes is water.
Do not apply the dry-basis biochar yield directly to wet mass. Doing so counts water as feedstock available for conversion and overstates the output.
2. Calculate biochar and its carbon mass
Multiply dry feedstock by the assumed dry-basis biochar yield. A 25% yield gives 1,271.25 × 0.25 = 317.8125 t/year of dry biochar. At an assumed 70% carbon content, the carbon mass is 317.8125 × 0.70 = 222.46875 t C/year.
Yield and carbon content are different inputs. Yield describes the mass of biochar obtained from dry feedstock. Carbon content describes how much of that biochar is carbon. Actual values require production measurements and laboratory analysis.
3. Convert carbon to gross CO₂ equivalent
The molecular-mass ratio of CO₂ to carbon is 44/12. Multiplying the carbon mass by this ratio gives 222.46875 × 44/12 = 815.71875 t CO₂e/year. This gross quantity does not yet account for durability or project emissions.
The ENVIID planning mode then applies an assumed 80% stable-carbon factor. That leaves 652.575 t CO₂e/year. It deducts an assumed 10% of that stable quantity, or 65.2575 tonnes, for project emissions.
4. Read the planning result correctly
The resulting estimate is 652.575 − 65.2575 = 587.3175 t CO₂e/year, displayed as 587.3. The complete planning expression is:
Wet mass × (1 − moisture) × dry yield × carbon content × 44/12 × 0.80 × 0.90
The last two factors are ENVIID planning assumptions. They are not universal certification defaults. The result is a scenario estimate, not issued carbon credits. An approved methodology, measured output, storage evidence, an emissions inventory and independent verification are needed to report verified removal.
5. Use operating hours and detailed emissions
At 6,300 operating hours per year, the wet feed rate required for this scenario is 2,250 × 1,000 / 6,300 = 357.14 kg/hour. Changing hours changes the required rate. It does not change annual output when the annual supplied mass stays fixed. This requirement is not proof of a reactor’s capacity.
The calculator’s detailed mode accepts a persistence fraction and emissions activity data for electricity, methane, transport, sourcing, security and other emissions. It requires factor sources and marks incomplete inputs. It does not silently replace missing evidence with the planning deductions.
Open the biochar carbon removal calculator to change the scenario. Read the digital MRV guide for the records that support the inputs. Isometric’s public biochar protocol provides a separate methodology reference for net-removal accounting.