Life cycle assessment of biochar-to-soil systems: A review

Abstract The climate change and soil degradation are among the most prominent environmental issues of today and solutions need to be looked for. Pyrolysis of (waste) biomass to produce biochar that is then applied to agricultural soil could be one of the means to tackle these problems. Many authors have used the Life Cycle Assessment method to evaluate the environmental impact of biochar-to-soil projects and in this paper those studies are systematically reviewed to uncover the overall trend. Although the differences in the contexts and characteristics of these studies disallow direct comparison of results, it is still obvious that the application of biochar brings significant benefits, either to neutralize the greenhouse gas emission of agricultural production or as a carbon capture method. There is also a great potential for energy production by utilizing the co-products - syngas and bio-oil. The benefits of carbon sequestration in biochar and the energy production usually overcompensate the greenhouse gas emissions produced during feedstock production and handling. However, the effect on other impact categories needs to be evaluated and limited and the economic sustainability of the project needs to be assured. To facilitate future progress, some methodology unification would be beneficial.