Integrating allocation methods and regional optimization in life cycle assessment of floating photovoltaics for cleaner energy transitions in China

Abstract

Floating photovoltaic (FPV) systems present a promising avenue for clean energy development by minimizing land-use conflicts and enhancing power generation efficiency. However, inconsistencies in life cycle assessment (LCA) allocation methods continue to obscure accurate carbon footprint estimations. This study demonstrated that the estimated carbon footprints of FPV systems ranged from 147.6 to 184.9 kg CO₂/m², with the Attributional with Production Output Substitution (APOS) method producing an intermediate value of 160.6 kg CO₂/m². To support strategic FPV deployment, we constructed a spatial optimization model tailored to China's seven grid zones, incorporating solar irradiance, grid carbon intensity, and system-level operational performance. The optimized allocation strategy could shorten the energy-based carbon payback time (EPBT) by up to 35.0 %, with current national averages ranging from 1.0 to 2.5 years. Scenario-based projections further suggest that as China's grid decarbonizes, EPBT will systematically rise from 13.6 months in 2023 to 16.7 months in 2030 and 18.9 months in 2035, due to diminishing marginal emission offsets. These insights underscore the time-sensitive value of near-term FPV adoption and offer a quantitative foundation for informed policy decisions, investment timing, and region-specific transition planning.