Residual Biomass, Sustainability Criteria and Availability
Our sister organization, atmosfair, together with the ifeu Institute for Energy and Environmental Research, has conducted a study on the potential availability of residual biomass. The study focuses on how much residual biomass is available in countries of the Global South for climate protection applications. One of these applications is the Biomass-to-Liquid (BtL) pathway, in which solid biomass residues are gasified and subsequently converted into synthetic crude oil through the Fischer–Tropsch process. Kerosene refined from this synthetic crude can be used in aircraft engines with a near carbon-neutral lifecycle.
BtL kerosene can be produced from residual biomass such as agricultural residues, sawmill wood chips, or dried sewage sludge. However, not all biomass feedstocks meet the sustainability principles of atmosfair and Solarbelt. Energy crops are particularly problematic because they compete with food production for agricultural land. Likewise, we do not support industrial crop cultivation that relies heavily on pesticides and synthetic fertilizers. Residues from production systems associated with human rights violations or that create dependencies for smallholder farmers are also excluded. Finally, we only consider genuine residual materials—biomass that has no higher-value alternative use, such as animal feed or mulch that protects agricultural soils from erosion.
To identify residual biomass that is environmentally and socially sustainable and available in sufficient quantities, the study derives a set of criteria from the United Nations Sustainable Development Goals
(SDGs). It first conducts a qualitative assessment to determine the general suitability of different types of biomass residues for climate protection applications. In a second, quantitative phase, it estimates the global potential of suitable residual biomass using a combination of expert interviews and external studies. No previous assessment has combined a comprehensive analysis of biomass availability with such extensive environmental and social sustainability criteria, making this study an important contribution that fills a significant knowledge gap.
The study shows that more than 90% of the solid residual biomass generated in the Global South does not meet our sustainability criteria. According to our conservative estimates, only around 420 million tonnes of residual biomass are both environmentally and socially sustainable and available for use. Even so, this resource base would be sufficient to produce around 40 million tonnes of BtL kerosene, enough to cover approximately 20% of global aviation fuel demand. Beyond reducing CO₂ emissions, the collection and processing of residual biomass could also support economic and social development in countries of the Global South, where communities are among those most severely affected by the impacts of climate change.
Illustration of the step-by-step selection of residual biomass using 11 criteria based on four environmental and social sustainability principles.