The study examines the environmental impact of the production of biochar from straw and sewage sludge using the pyrolysis process and its utilization. The aim is to evaluate the ecological advantages and disadvantages of this technology and to compare it with existing energetic utilization systems for straw in combined heat and power plants and sewage sludge in mono-incineration plants. The entire life cycle is analyzed, from the provision of biomass to the agricultural use of biochar.
The results show that biochar can make an important contribution to the reduction of greenhouse gases through the long-term storage of carbon – the sequestration. In addition, pyrolysis can supply energy in the form of heat and electricity, which means that fossil fuels can be substituted. This leads to a significantly better carbon footprint compared to the reference systems. Using a solely energetic balance, pyrolysis has more CO2-equivalent emissions than the respective reference process. In other impact categories such as acidification or eutrophication, pyrolysis generally has higher environmental impacts compared to the reference system.
The study underlines the potential of pyrolysis to achieve climate and negative emissions targets by storing carbon and providing renewable energy. At the same time, challenges such as resource consumption and emission reduction in the process are highlighted. Overall, the LCA shows that pyrolysis can be a sustainable option for biomass utilization. The results of the study can be interpreted differently depending on the question posed. If the focus is on the generation of negative emissions, pyrolysis offers a promising option. However, if the focus is on providing renewable energy, conventional ways of utilizing straw and sewage sludge in a combined heat and power plant and mono incineration are ecologically more advantageous.