Scenario analysis of hydrochar production for incorporation into boreal soils: a life cycle and technoeconomic assessment

Agriculture and forest ecosystems are significant contributors to greenhouse gas (GHG) emissions, making mitigation strategies essential for sustainable land application. This study assesses the sustainability impact of converting wood residues into hydrochar for use as a soil amendment to reduce GHG emissions and enhance carbon sequestration. Through a comprehensive life cycle assessment (LCA) and technoeconomic analysis (TEA) of establishing hydrothermal carbonization (HTC) process in pulp and paper mills, this research addresses a critical knowledge gap. The LCA indicates that applying hydrochar in boreal soils without additional fertilizers is advantageous in terms of climate change mitigation, resulting in net CO₂-equivalent savings of up to 300 kg per year. The TEA indicates that although advanced technologies for wastewater treatment from the HTC process entail higher initial costs, they yield greater financial returns compared to conventional methods. These findings suggest that HTC units have the potential to offer climate change mitigation benefits and improved economic performance when valorizing wood residues compared to the mono-incineration process.