Darzin International Company Multidisciplinary Engineering Science Open 1 Serial Number 1 2024 02 01 Life-Cycle Assessment of Negative-Emissions Technologies: System Boundaries, Co-Benefits, and Trade-Offs Life-Cycle Assessment of Negative-Emissions Technologies: System Boundaries, Co-Benefits, and Trade-Offs 1 11 EN Journal Article 2023 11 18 <p class="Abstract" style="line-height: 150%;"><span style="font-size: 8.0pt; line-height: 150%;">This review aims to critically synthesize the life-cycle assessment (LCA) literature on negative-emissions technologies (NETs) to evaluate how system boundaries, co-benefits, and trade-offs have been operationalized across diverse pathways. A qualitative literature review was conducted using fifteen peer-reviewed studies selected from major scientific databases, including Scopus and Web of Science. The analysis focused exclusively on LCAs of NETs, employing theoretical saturation to ensure conceptual completeness. Data were extracted and coded using NVivo 14 software, with open, axial, and selective coding applied to identify key themes related to system boundary definition, environmental and socioeconomic co-benefits, trade-offs, and comparative assessment across NETs such as bioenergy with carbon capture and storage (BECCS), direct air capture (DAC), enhanced weathering, and biochar systems. The review revealed significant methodological heterogeneity in LCA of NETs, particularly in system boundary selection, functional units, temporal treatment of carbon storage, and inclusion of indirect effects. Co-benefits such as improved soil fertility, biodiversity enhancement, and air quality improvement were often reported alongside trade-offs including land-use competition, water demand, and energy intensity. Comparative analyses across NET pathways indicated that technology-specific impacts vary substantially, with hybrid and integrated systems offering potential synergies but remaining underrepresented in existing studies. Thematic synthesis highlighted the need for transparent boundary definition, inclusion of socioeconomic dimensions, and sensitivity analyses to improve credibility and comparability. NET LCAs exhibit substantial variability and uncertainty, yet provide critical insights into environmental trade-offs and co-benefits. Standardized methodological frameworks, transparent reporting, and integration of social and ecological impacts are essential to guide policy and technology deployment decisions. Harmonized approaches will facilitate robust comparisons, inform climate mitigation strategies, and support sustainable scaling of NETs to achieve net-negative emissions targets.</span></p> https://jmesopen.com/index.php/jmesopen/article/download/35/30