Life Cycle Carbon Emission Assessment of Modular Marine Floating Structures Based on S*-LCA Method

Against the backdrop of intensifying global carbon emissions and growing coastal land demand, deep-sea development is becoming a critical expansion direction. Marine floating structures, which occupy no land and can be deployed in deep-sea areas, offer a promising solution for future energy and spatial needs. However, quantitative research on their life-cycle carbon emissions remains limited, hindering the identification of high-emission stages and the formulation of effective low-carbon strategies during design. This study adopts the Streamlined Life Cycle Assessment (S*-LCA) method to evaluate a marine floating platform composed of 20 linearly connected buoyancy units under two construction scenarios: modular prefabrication and traditional cast-in-situ. A quantitative analysis of greenhouse gas emissions was conducted across the platform’s entire life cycle, from raw material extraction to demolition. Results show that the modular prefabricated scheme generates total emissions of 25.66 × 10⁶ kg CO₂eq, approximately 28.06% lower than the traditional scheme (35.66 × 10⁶ kg CO₂eq). Per-unit carbon emission intensity is 1.28 × 10⁶ kg CO₂eq and 1.78 × 10⁶ kg CO₂eq, respectively. The operation and maintenance (O&M) stage is the largest emission source in both schemes, accounting for 55.43% (prefabricated) and 58.65% (traditional), followed by raw material supply, where ultra-high-performance concrete and steel fibers are key contributors. Transportation emissions differ markedly: centralized prefabrication and integrated marine transport limit emissions to 1.25% in the modular scheme, whereas multi-stage land and sea transport raise the share to 10.17% in the traditional scheme. Construction and demolition phases contribute minimally in both cases. The study quantifies emission profiles of marine floating structures and highlights key reduction opportunities in material production and O&M, providing a scientific basis for green construction and carbon reduction strategies in future marine engineering.