Assessment of municipal solid waste torrefaction for sustainable biochar production: A comprehensive life cycle evaluation of eight process scenarios

Rapidly increasing municipal solid waste (MSW) generation in developing countries presents significant environmental and resource management challenges. Conventional disposal methods such as landfilling and incineration lead to greenhouse gas (GHG) emissions, pollution, and missed opportunities for resource recovery. This study aims to evaluate the environmental performance of MSW torrefaction for sustainable biochar production using a life cycle assessment (LCA) approach.Eight processing scenarios (S1–S8) were developed by varying configurations of sorting, shredding, drying, and torrefaction. LCA was conducted under a gate-to-gate boundary using primary data from Dehradun, India, and environmental impacts were assessed across six categories; global warming potential (GWP), freshwater eutrophication potential (FEP), land use (LU), and human toxicity potential (HTP), acidification potential (AP) and particulate matter formation potential (PMFP) based on the ReCiPe 2016 framework. Scenario S1, which integrates air drying and renewable electricity use, was identified as the most sustainable configuration, achieving a net GWP of −1.724 kg CO₂ eq/kg biochar, LU benefit of −0.079 m²·a crop eq, and favourable trade-offs across other categories. Sensitivity analysis based on monte Carlo technique, confirmed S1’s robustness under operational variability, while comparative assessments with literature and commercial systems validated its environmental advantages. This work highlights the viability of decentralized, low-tech torrefaction systems for climate-resilient waste management and carbon-negative biochar production in low-resource settings. Future research should focus on region-specific validation, upscaling challenges, and integration with agricultural value chains.