Biochar and Biomass Process Modeling

Transparent engineering models, Cantera-based reactor examples, curated simulation data, and technical documentation for biomass thermochemical conversion, biochar formation, syngas generation, heat production, and screening-level carbon-management assessment.

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Purpose

Biomass thermochemical conversion involves strongly coupled physical and chemical processes, including:

• feedstock heating;
• moisture evaporation;
• primary devolatilization;
• tar formation and cracking;
• gas-phase oxidation;
• char formation;
• char oxidation and gasification;
• heat release and heat consumption;
• residence-time effects;
• feedstock and operating-condition variability.

This repository provides a transparent starting point for examining these interactions through simplified reactor calculations, curated simulation results, and structured engineering interpretation.

The objective is not to provide a universally predictive biomass-conversion model. It is to support:

• process understanding;
• sensitivity analysis;
• model reconstruction;
• reproducible calculation workflows;
• validation planning;
• early-stage process comparison;
• responsible technical communication.

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Practical Engineering Questions

The repository is intended to support questions such as:

• How do temperature, moisture, oxygen availability, and residence time influence predicted biomass conversion?
• Under which conditions does the simplified model favor char, tar, permanent gases, or oxidation products?
• How do drying, pyrolysis, partial oxidation, and gasification interact in the current reaction scheme?
• How sensitive are predicted biochar and syngas yields to operating assumptions?
• Which model parameters require experimental validation?
• Which trends are robust, and which may result from model structure or unit assumptions?
• What information is required before transferring a simulation result to pilot or industrial scale?
• How should heat generation, syngas use, carbon retention, and emissions be compared across thermochemical process concepts?
• Which additional measurements are needed before discussing carbon-storage or carbon-credit potential?

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Application Scope

The current repository addresses selected aspects of:

• biomass pyrolysis;
• biochar formation;
• partial oxidation;
• simplified biomass gasification;
• syngas-component formation;
• heat generation;
• residence-time effects;
• moisture sensitivity;
• temperature sensitivity;
• oxygen-to-inert-gas sensitivity;
• preliminary carbon-retention and carbon-management screening.

The repository may support:

• scientific and engineering education;
• early-stage process evaluation;
• qualitative sensitivity studies;
• model and mechanism reconstruction;
• preparation of experimental programmes;
• development of more advanced reactor models;
• technical communication related to biomass and waste-to-X concepts.

It should not be interpreted as a complete industrial biochar-plant simulator.

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Current Model Representation

The current Cantera mechanism uses a simplified, pseudo-homogeneous representation of biomass conversion.

Pseudo-species such as:

• WOOD;
• CHAR;
• TAR;
• selected gas-phase products;
• water

are represented within a common reaction framework to examine approximate conversion pathways and qualitative process trends.

The mechanism includes simplified representations of processes such as:

• moisture evaporation;
• wood decomposition;
• tar formation and cracking;
• gas-phase oxidation;
• char oxidation;
• char gasification;
• methanation;
• water–gas-shift chemistry.

This formulation is useful for screening and model development, but it does not constitute a complete multiphase biomass-reactor description.

The current model does not explicitly resolve:

• biomass-particle geometry;
• internal particle-temperature gradients;
• particle shrinkage;
• pore development;
• intraparticle diffusion;
• detailed mineral and ash chemistry;
• feedstock-specific biochemical composition;
• tar speciation;
• aerosol formation;
• solid–gas momentum coupling;
• radiation inside a particle bed;
• detailed reactor hydrodynamics;
• equipment heat losses;
• industrial control behavior.

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Current Repository Contents

The repository currently includes:

• a structured public repository;
• selected publication references;
• a Cantera-compatible wood-pyrolysis mechanism;
• the preserved original simulation script;
• refactored Python modules for further development;
• a parameterized command-line entry point;
• representative curated simulation data;
• sensitivity cases for:
  • moisture;
  • temperature;
  • oxygen/inert-gas composition;
• feedstock and carbon-screening utilities;
• documentation of assumptions and limitations;
• model-consistency notes;
• a validation-development plan;
• basic automated software tests.

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Scientific and Engineering Basis

The repository is connected to the following technical works:

Biomass Conversion and Biochar Production

Enhancing Biomass Conversion: Advanced Modelling and Process Optimization for Efficient Biochar and Heat Production

DOI: 10.5281/zenodo.19438451

Waste-to-X and Carbon-Management Context

Advancing Waste-to-X Technologies: Sustainable Thermochemical Pathways for Biomass Valorization and Carbon Credit Potential

DOI: 10.5281/zenodo.19785243

Process-Development and Scale-Up Framework

Thermochemical Process Development: From Mechanism to Scale-Up and Industrial Adoption

DOI: 10.5281/zenodo.20760609

These publications provide scientific and engineering context. The current repository does not automatically reproduce every published figure, value, or conclusion.

Exact reproduction requires confirmation of:

• model version;
• mechanism version;
• initial conditions;
• temperature units;
• feed composition;
• reactor assumptions;
• numerical settings;
• post-processing method.

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Curated Simulation Data

Selected Cantera simulation outputs are provided in data/curated/.

They allow the qualitative examination of:

• biomass conversion;
• predicted char formation;
• moisture effects;
• temperature effects;
• oxygen/inert-gas effects;
• carbon monoxide formation;
• hydrogen formation;
• methane formation;
• carbon dioxide formation.

The current sensitivity groups are stored in:

data/curated/moisture_sweep_T790_O2-N2-23-77/
data/curated/temperature_sweep_H2O10_O2-N2-23-77/
data/curated/oxygen_sweep_H2O10_T790/

A case overview is provided in:

data/manifest_simulation_cases.csv

Supporting notes are available in:

data/README.md
docs/model_consistency_notes.md
docs/model_validation_plan.md

The curated CSV files contain simulation results, not experimental measurements.

They are suitable for:

• qualitative comparison;
• trend visualization;
• regression checking;
• documentation;
• development of plotting and analysis tools.

They should not be used directly as validated design data for an industrial biomass or biochar facility.

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Quick Start

Using Conda

Create and activate the environment:

conda env create -f environment.yml
conda activate biochar-carbon

Using venv and pip

python -m venv .venv

On Linux or macOS:

source .venv/bin/activate

On Windows:

.venv\Scripts\activate

Install the dependencies:

pip install -r requirements.txt

Run a representative case:

python scripts/run_biochar_case.py \
  --temperature-k 1063.15 \
  --biomass-kg-h 100 \
  --air-kg-h 466 \
  --moisture 0.10 \
  --ash 0.015 \
  --time-s 1800 \
  --output results/base_case.csv

The mechanism is stored in:

mechanisms/Wood_pyrolysis.yaml

The preserved original script is stored in:

originals/blasi_original.py

The original script is retained for provenance and reconstruction. Its presence does not imply that every equation, parameter, unit, or numerical implementation has been independently validated.

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Important Temperature-Unit Issue

The original script contains:

tk = 790.0

and passes this value to Cantera as Kelvin.

However, some associated publication figures and captions refer to temperatures such as:

780 °C
790 °C
800 °C

These values are not equivalent to 780, 790, and 800 K.

For example:

790 °C = 1063.15 K

Therefore, published and archived results should not be described as exactly reproduced until the original temperature basis has been confirmed.

This issue is documented in:

docs/model_consistency_notes.md

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Repository Structure

biochar-process-modeling/
│
├── README.md
├── CITATION.cff
├── LICENSE
├── LICENSE_NOTES.md
├── MANIFEST.md
├── pyproject.toml
├── requirements.txt
├── environment.yml
│
├── data/
│   ├── README.md
│   ├── manifest_simulation_cases.csv
│   └── curated/
│       ├── moisture_sweep_T790_O2-N2-23-77/
│       ├── temperature_sweep_H2O10_O2-N2-23-77/
│       └── oxygen_sweep_H2O10_T790/
│
├── docs/
│   ├── model_scope.md
│   ├── assumptions_and_limitations.md
│   ├── carbon_credit_caution.md
│   ├── model_consistency_notes.md
│   ├── model_validation_plan.md
│   ├── publications.md
│   ├── repository_roadmap.md
│   ├── github_profile_snippet.md
│   └── source_publications/
│
├── mechanisms/
│   ├── Wood_pyrolysis.yaml
│   └── Wood_pyrolysis.cti
│
├── originals/
│   └── blasi_original.py
│
├── src/
│   └── biochar_model/
│       ├── __init__.py
│       ├── cantera_reactor.py
│       ├── feedstock.py
│       └── carbon_screening.py
│
├── scripts/
│   └── run_biochar_case.py
│
├── examples/
│   └── run_base_case.py
│
├── notebooks/
│   └── README.md
│
└── tests/
    └── test_feedstock.py

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Evidence and Maturity

Current status: Research reconstruction and engineering screening framework.

The repository currently provides:

• a documented model structure;
• executable Python and Cantera components;
• curated simulation outputs;
• qualitative sensitivity cases;
• model-consistency documentation;
• transparent limitations;
• basic software tests;
• a foundation for further validation.

The available software tests verify selected program behavior. They do not establish that the thermochemical mechanism is quantitatively predictive.

The current repository does not yet provide:

• comprehensive elemental and mass-balance validation for every case;
• feedstock-specific kinetic calibration;
• experimentally validated product yields;
• validated tar composition;
• validated char properties;
• validated reactor heat-transfer behavior;
• validated residence-time distributions;
• industrial-scale equipment design;
• techno-economic analysis;
• lifecycle assessment;
• formal carbon-credit quantification;
• guaranteed process performance.

Results should therefore be presented as screening-level or research-development evidence unless validated independently.

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Validation Requirements

Progress toward a predictive model would require, among other activities:

• confirming all temperature and flow-rate units;
• verifying elemental balances;
• verifying total mass conservation;
• checking reaction stoichiometry;
• reviewing kinetic parameters and original sources;
• clarifying the physical interpretation of pseudo-species;
• validating moisture-evaporation treatment;
• comparing predicted gas yields with experimental measurements;
• comparing char yield with feedstock-specific data;
• validating tar and condensable-product behavior;
• introducing particle-scale heat and mass transfer where required;
• characterizing reactor hydrodynamics;
• evaluating numerical sensitivity;
• documenting the model applicability domain.

Validation should be conducted against datasets with sufficiently clear information on:

• feedstock composition;
• particle size;
• moisture;
• ash;
• heating rate;
• pressure;
• temperature history;
• residence time;
• atmosphere;
• reactor configuration;
• analytical method;
• product collection and closure.

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Development Priorities

The next development priorities are:

1. verify the current mechanism, units, and mass balances;
2. reproduce selected archived cases under documented conditions;
3. add automated balance and conservation checks;
4. generate publication-quality plots from the curated data;
5. parameterize the reactor calculations more consistently;
6. separate feed preparation, reactor simulation, and post-processing;
7. evaluate temperature, moisture, atmosphere, and residence-time sensitivities;
8. compare results with suitable experimental or literature datasets;
9. define the model applicability domain;
10. develop higher-fidelity particle and reactor descriptions only where justified.

Development should proceed from verified foundations rather than by adding complexity before the current model has been fully audited.

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Carbon-Management and Carbon-Credit Caution

The repository may support preliminary discussion of:

• carbon retained in char;
• carbon released to gas;
• potential energy substitution;
• process-emission sources;
• qualitative carbon-management pathways.

It does not certify carbon removal or carbon credits.

A formal carbon-credit or durable carbon-removal claim requires an applicable methodology and evidence covering, as relevant:

• biomass sourcing;
• counterfactual baseline;
• additionality;
• process-energy use;
• transport emissions;
• methane and nitrous-oxide emissions;
• char carbon content;
• stability and permanence;
• intended end use;
• leakage;
• monitoring;
• reporting;
• verification;
• uncertainty;
• chain of custody.

Screening calculations from this repository should therefore not be presented as investment-grade, regulatory, certification, or credit-issuance evidence.

See:

docs/carbon_credit_caution.md

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Responsible Use

This repository is intended for:

• research;
• education;
• model development;
• engineering screening;
• sensitivity analysis;
• reproducibility;
• validation planning;
• early-stage process comparison.

It does not constitute:

• a final reactor design;
• a process-safety assessment;
• a regulatory recommendation;
• an emissions guarantee;
• an investment-grade feasibility study;
• a carbon-credit certification;
• a guarantee of industrial biochar or syngas performance.

Industrial application requires independent experimental validation, engineering design, process-safety review, materials assessment, environmental evaluation, economic assessment, and scale-up verification.

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Documentation

Relevant documentation includes:

• Model Scope
• Assumptions and Limitations
• Model Consistency Notes
• Model Validation Plan
• Carbon-Credit Caution
• Publications
• Repository Roadmap
• Data Documentation

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Citation

Citation metadata are provided in:

CITATION.cff

Users should cite the repository version and the relevant underlying technical publication when reusing the software, data, calculations, or methodology.

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License

The repository is distributed under the MIT License unless otherwise stated.

See:

LICENSE
LICENSE_NOTES.md

Historical programs, mechanisms, datasets, and publication materials may have separate provenance or reuse conditions. Users should review the relevant documentation before redistribution.

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Author

Ahmad Saylam

R&D & Technology Development Leader
Scientific & Engineering Consultant