Biochar-Now: GFZ

Biochar from waste materials to reduce CO₂ in the atmosphere (CDR) – potential and environmental risks

In order to keep the rise in global warming below 2ºC (Paris Agreement), it has become clear that the mere reduction of greenhouse gas emissions will not be sufficient and that CO₂ drawdown from the atmosphere will be essential. One technological solution is the pyrolytic fixation of photosynthetically generated biomass to biochar. Biochar products are mainly used as an agricultural enhancer, where it acts, amongst other factors, as a source of nutrients and a means for enhanced retention of soil humidity, whereas the coal itself remains inert and leads to long-term storage of CO₂-derived carbon in soils. As a side effect, the pyrolysis process generates surplus energy, which can be used in a process chain for heating or electricity production. The largest concern in terms of using waste feedstock relates to the potential presence of harmful pollutants and heavy metals in these materials. In the proposed project we will generate biochar from various waste streams, test whether the laboratory pyrolysis results can be upscaled to commercial pyrolysis reactors, analyze the organic and inorganic composition of the different waste-based biochars and evaluate their release potential for harmful pollutants and heavy metals under laboratory and more natural conditions using leaching experiments. To investigate the fate of waste-based biochars in soils, moreover, the interaction of biochar with microbial communities and their impact on the biochar chemistry and mobilization of harmful pollutants will be studied in detail. Using these results, we will evaluate upscaling-potential, feasibility, and likelihood of success for various potential source/application scenarios, leading to clear scientifically-based recommendations.

The Biochar-Now Project is part of the BMFTR funded CDRterra research program on land-based CO₂ removal (CDR) methods

Partners:

Funding: Federal Ministry of Research, Technology and Space (BMFTR)

Funding code: 01LS2515A