Biochar replaces peat in horticulture: Environmental impact assessment of combined biochar & bioenergy production

Abstract

Horticulture in temperate climate zones is energy intensive and the use of peat as the main ingredient in substrates releases additional GHG emissions during mining and processing. This paper evaluates the environmental impact of the co-production and application of bioenergy and biochar using agricultural and woody feedstock to replace natural gas and peat in horticulture by means of a life cycle analysis (LCA), including the timing of CO2 release and uptake, the decay of peat and biochar and the carbon stability of biochar and peat. Lab-scale data on biochar carbon recalcitrance compared to peat (~80% vs. 40% respectively) indicate that spent biochar-based substrates in soil are a carbon storage tool. The combination of bioenergy replacing fossil energy, biochar replacing peat in substrate and long term storage of the spent biochar in soil, contribute to GHG reductions.