Biomass
Introduction
Biomass is organic matter derived from living or recently living organisms. It includes materials such as wood, crop residues, grasses, organic waste, manure or algae. Biomass is the primary source of carbon for biochar and therefore the starting point of every biochar-based value chain.
All biomass consists mainly of carbon, hydrogen and oxygen, bound together in complex organic structures known as fibres. These fibres are typically composed of cellulose, hemicellulose and lignin. The relative proportions of these components differ significantly between biomass types — and this has a direct influence on how biomass behaves during conversion and on the quality of the resulting biochar.
For example, woody biomass generally contains a higher proportion of lignin. This makes it more structurally stable and typically results in biochar with higher carbon content, greater stability and a more rigid pore structure. Grasses and agricultural residues, on the other hand, usually contain more cellulose and hemicellulose and often higher mineral (ash) content. This can lead to biochar with different surface properties, nutrient content and reactivity, which may be advantageous for certain applications but less suitable for others.
Understanding these differences is essential. Biomass is not interchangeable, and the choice of feedstock strongly affects:
- biochar yield and carbon stability,
- physical and chemical properties of the biochar, and
- suitability for specific applications, such as soil improvement, construction materials or technical uses.
TASKS
Different types of biomass: Sort the types of biomass into the two categories.
Reflection
Think about biomass streams that are part of your region or your everyday environment, such as garden waste, food waste, crop residues, wood offcuts or green waste from public spaces.Choose one or two examples and follow their pathway:
- Where does the biomass originate?
- How is it collected or handled?
- What happens to it after collection (e.g. composting, incineration, disposal, reuse)?
- At which point is the carbon released or retained?
Reflect briefly on how these biomass streams are currently used. Note down your observations and reflections.
BIOCHAR CHAIN
Biochar production is not a single step, but a complex sequence of activities. This process requires organised roles, from handling raw biomass to converting it through pyrolysis and applying it in practical uses.
Each role in this chain focuses on a specific part of the process and brings its own priorities and constraints. Understanding these roles helps clarify how biochar projects function in practice and where challenges or opportunities may arise.
The following video introduces the main roles within the biochar chain and explains what each contributes to the process, as well as the key challenges they encounter along the way.
Understanding Stakeholder Roles in the Biochar Chain
Below you find the people from the video together with their statements, as well as statements describing main interests. Identify which role each person plays in the biochar value chain and assign both the person’s statement and the corresponding main-interest statement to the correct role using drag and drop.
Reflection: Your Link to the Biochar Chain
Reflect on your own position in the biochar value chain. Which role best matches your current background, activities or interests?
Briefly describe:
- The role you see yourself in
- Your main motivation or interest
- Any challenges or questions you associate with this role
BIOMASS SOURCES & PROPERTIES
Biomass comes from many different sources, and its properties vary widely depending on origin, composition and treatment. These differences strongly influence how biomass behaves during pyrolysis and what kind of biochar can be produced.
Not all biomass is equally suitable for biochar production. Materials differ in moisture content, ash content, fibre structure and chemical composition, which affects conversion efficiency, process stability and biochar quality. Harvesting, collection and preparation efforts can also vary significantly between biomass types.
Biomass is rarely unused — in most regions it already serves established purposes such as energy production, material use or composting. Biochar introduces additional and often higher-value pathways for using these same resources, but it must demonstrate clear benefits to be viable in practice. Understanding where biochar applications add value, fit existing systems and make effective use of biomass is therefore essential.
This makes it important to examine biomass sources not only in terms of availability, but also in terms of quality, current use and suitability for biochar production.
Let us explore the diversity of biomass and analyse its potential for sustainable biochar production.
Reflection: Is Your Biomass Suitable for Pyrolysis?
Revisit the one or two biomass streams you analysed in the beginning of this module (LU1, Task b, hier vielleicht das dort eingegebene nochmals darstellen?). Now assess whether these materials are suitable for pyrolysis based on their key properties.
For each biomass stream, consider:
- Is the biomass dry enough, or would drying be required?
- Is it solid and reasonably uniform, or highly mixed?
- Is the particle size suitable, or would shredding, chipping or sorting be needed?
- Does it have a sufficient and reasonably consistent calorific value (typically at least ~10 MJ/kg on a dry basis)?
Briefly note:
- Which properties already fit
- Which properties would need improvement
BIOMASS Preparation
Before biomass can be converted into biochar, it must be properly prepared. Biomass preparation includes all steps that take place before pyrolysis — from harvesting and collection to transport, storage and pre-treatment.
The way biomass is handled during these stages largely determines whether it becomes a reliable and suitable feedstock for pyrolysis. Moisture content, contamination, particle size and material uniformity are shaped by decisions made during preparation and handling.
This learning unit focuses on the key preparation steps: harvesting or collection, transport and storage, and pre-treatment measures such as drying, sorting and size reduction. Understanding these steps clarifies how raw biomass is transformed into a consistent input for biochar production and why preparation is a critical part of the biochar chain.
Reflection: What Does Your Biomass Need Before Pyrolysis?
Think back to the biomass streams you identified at the beginning of this learning module. Choose one example and consider it in more detail from a preparation perspective.
Reflect on the following questions:
- Which preparation steps would be most relevant for this biomass (e.g. separation, pressing, shredding, drying, sieving)?
- Where do you see the main challenges along the chain — during harvesting, logistics, storage or drying?
- Are there existing structures or resources in your context (such as waste management sites, storage areas or excess heat from other processes) that could support biomass preparation?
Local/Regional Investigations on Residual Biomass
Throughout this module, you have explored what biomass is, how it differs in origin and properties, and what is required to prepare it for pyrolysis. You have already worked with examples of biomass streams from your region and examined how they are collected, handled and used.
Now, let’s bring these pieces together. In this summarizing unit, you will return to your selected biomass stream and create a structured profile of it based on the criteria discussed so far. You will assess its key properties, availability and current use, and make a first, well-reasoned judgement about its suitability for pyrolysis.
This synthesis step connects knowledge with application. It helps you consolidate what you have learned into a coherent assessment and prepares you to move forward from biomass characteristics toward understanding biochar itself in the next module.
Reflection: Open Questions and Support Needs
After working through the module and assessing your biomass, reflect on what came up for you during the learning process.
Reflection prompts:
- What questions about biomass and its preparation emerged for you?
- Which aspects of biomass suitability do you feel least confident about?
- What kind of information, examples or support would help you better assess biomass in the future?