The costs and benefits of biochar production and use: A systematic review

Besides being an opportunity to valorize biomass residues, biochar (i.e., the solid product of biomass pyrolysis) has many potential environmental benefits, such as climate change mitigation and reduced nutrient leaching. Even though the academic interest in biochar has increased, it is not being used at a large scale yet, mainly because of its economic feasibility compared to fertilizers and because farmers are either unaware of or skeptical about its effects. In this paper, the economics of biochar are examined by performing a systematic review, following the guidelines of the Collaboration for Environmental Evidence. Specifically, it has been examined to which extent the production and application of biochar are yet profitable from an investor's perspective and desirable from a societal perspective. For the first time, this review investigates the extent to which previous studies have included external costs and benefits. We find that profitability and desirability of biochar production and use are highly uncertain and case-specific, depending on factors like location, feedstock, scale, pyrolysis conditions, biochar price, cultivated crop, and the potential internalization of externalities, which hampers private investment. To advance biochar development and deployment, those factors must be considered carefully for each case. Although externalities are included in the literature to some extent, the focus is mostly on external benefits rather than external costs, often focusing on its carbon sequestration potential. The inclusion of externalities in economic assessments is necessary to provide solid arguments to develop policies for the acceleration of market uptake of biochar technology.