The greenest solar power? Life cycle assessment of foam-based flexible floatovoltaics

Abstract

This study presents a life cycle analysis (LCA) of a 10 MW foam-based floatovoltaics (FPV) plant installed on Lake Mead, Nevada, U.S. A material inventory of the flexible crystalline silicon (c-Si)-based module involved massing and determination of material composition of the module's encapsulation layers with ATR/FTR spectroscopy and electron microscopy. The LCA was performed using SimaPro and the results were interpreted in terms of cumulative energy demands, energy payback time, global warming potential, GHG emissions, and water footprint including negative values for reduced evaporation. A sensitivity analysis was performed on the lifetime of the modules and the foam-based racking. The results show that the 30 year lifetime foam-based FPV system has one of the lowest energy payback times (1.3 years) and the lowest GHG emissions to energy ratio (11 kg CO₂ eq per MW h) in c-Si solar PV technologies reported to date. In addition, the foam-based FPV system also had 5 times less water footprint (21.5 m³ per MW h) as compared to a conventional pontoon-based FPV (110 m³ per MW h). The lifetime of the foam-based racking does not affect the result, while the lifetime of the modules has a significant effect on the lifecycle impacts of the foam-based FPV plant. Foam-based FPV has a net positive impact on the environment for CO₂ emissions and energy consumption if its lifetime is above 7.4 years and the technology has the potential to become the greenest c-Si-based solar PV technology if the lifetime of the modules can be guaranteed for at least 26.6 years. Future work is needed to determine the lifetimes of these systems and expand them.