Department of Sustainable Development, Environmental Engineering, and Sciences (SEED), KTH Royal Institute of Technology, Sweden.
Department of Soil and Environment, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
J Environ Manage. 2021 May 15;286:112154. doi: 10.1016/j.jenvman.2021.112154. Epub 2021 Feb 17.
Biochar has been recognised as a carbon dioxide removal (CDR) technology. Unlike other CDR technologies, biochar is expected to deliver various valuable effects in e.g. agriculture, animal husbandry, industrial processes, remediation activities and waste management. The diversity of biochar side effects to CDR makes the systematic environmental assessment of biochar projects challenging, and to date, there is no common framework for evaluating them. Our aim is to bridge the methodology gap for evaluating biochar systems from a life-cycle perspective. Using life cycle theory, actual biochar projects, and reviews of biochar research, we propose a general description of biochar systems, an overview of biochar effects, and an evaluation framework for biochar effects. The evaluation framework was applied to a case study, the Stockholm Biochar Project. In the framework, biochar effects are classified according to life cycle stage and life cycle effect type; and the biochar's end-of-life and the reference situations are made explicit. Three types of effects are easily included in life cycle theory: changes in biosphere exchanges, technosphere inputs, and technosphere outputs. For other effects, analysing the cause-effect chain may be helpful. Several biochar effects in agroecosystems can be modelled as future productivity increases against a reference situation. In practice, the complexity of agroecosystems can be bypassed by using empirical models. Existing biochar life cycle studies are often limited to carbon footprint calculations and quantify a limited amount of biochar effects, mainly carbon sequestration, energy displacements and fertiliser-related emissions. The methodological development in this study can be of benefit to the biochar and CDR research communities, as well as decision-makers in biochar practice and policy.
生物炭已被视为一种二氧化碳去除（CDR）技术。与其他 CDR 技术不同，生物炭有望在农业、畜牧业、工业过程、修复活动和废物管理等方面带来各种有价值的效果。生物炭对 CDR 的多种副作用使得对生物炭项目进行系统的环境评估具有挑战性，而且迄今为止，还没有用于评估它们的通用框架。我们的目标是弥合从生命周期角度评估生物炭系统的方法差距。使用生命周期理论、实际的生物炭项目以及对生物炭研究的综述，我们提出了生物炭系统的一般描述、生物炭效果概述以及生物炭效果评估框架。该评估框架应用于一个案例研究，即斯德哥尔摩生物炭项目。在该框架中，根据生命周期阶段和生命周期效应类型对生物炭效应进行分类；并明确了生物炭的使用寿命结束和参考情况。生命周期理论中很容易包含三种类型的效应：生物圈交换、技术圈投入和技术圈产出的变化。对于其他效应，分析因果关系链可能会有所帮助。农业生态系统中的几种生物炭效应可以建模为相对于参考情况的未来生产力增加。在实践中，可以通过使用经验模型来绕过农业生态系统的复杂性。现有的生物炭生命周期研究通常仅限于碳足迹计算，并量化了有限数量的生物炭效应，主要是碳封存、能源替代和与肥料相关的排放。本研究中的方法学发展可以使生物炭和 CDR 研究界以及生物炭实践和政策的决策者受益。
