Biochar: a win-win-win solution for sustainable small-scale farming in Sweden?

Sammanfattning: Biochar is a recalcitrant carbon rich solid product widely praised for the ability to improve soil fertility and sequester carbon, thereby improving crop yields and mitigating climate change. In addition to this, gaseous by products from production can be combusted for energy. Despite the recent global peaks in biochar research, studies focused on temperate regions are relatively scarce and few European farmers are familiar with the concept. At Håkan Rasmusson Golf och Lantbruk (HRGL), a 40-ha farm in southern Sweden, the potential for biochar production using cheap and simple production technology (a double barrel charcoal kiln) is being investigated. This report aims to theoretically study whether biochar production will benefit the farm in terms of increased crop yields, climate change mitigation and energy production, using a literature review and an enthalpy-based energy model. The results show that it is possible to fulfil the annual heat requirement of 30 000 kWh using a double barrel kiln. This could also result in a net offset of approximately 1.96 tons CO2e per year. Increased crop yields are unlikely, though biochar might positively affect other soil parameters, for example water holding capacity, in a way that could protect the soil from future resource limitations. However, there is a contradiction between production optimised for soil improvement and production optimised for climate regulation and energy production. In conclusion, biochar production is likely to be overall beneficial to HRGL. This report highlights the many factors to consider for a successful biochar production system but contains many assumptions and potential sources of error. It is strongly suggested that practical implementation is combined with monitoring to confirm the results of this study.