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.