Energy-Water Nexus: Floating Solar for Treating Inland Water Bodies

Abstract The accelerating impacts of climate change are intensifying pressure on freshwater ecosystems while simultaneously increasing demand for low-carbon energy solutions. Rising temperatures, altered precipitation patterns, and nutrient enrichment are driving the proliferation of harmful algal blooms (HABs) in inland water bodies, degrading water quality and threatening public health and ecosystem resilience. Addressing these challenges requires integrated engineering solutions that couple renewable energy generation with sustainable water treatment. This paper presents a hybrid Floating Photovoltaic–Ultraviolet (FPV–UV) system designed to deliver renewable-powered, in-situ treatment of eutrophic inland waters. The system combines floating solar photovoltaics with UV disinfection to provide chemical-free algal control while operating independently of grid electricity. Lough Neagh, Northern Ireland’s largest freshwater lake, is used as a case study to evaluate system feasibility under representative climatic and hydrological conditions. In addition, the hydraulic performance, UV treatment efficiency, and energy balance of the designed model are assessed. Results demonstrate that the proposed FPV–UV platform can sustain a treatment flow rate of 3 m3/s while remaining energy self-sufficient through on-site solar generation. The modular design enables scalability and adaptability to different lake environments, offering a transferable engineering solution at the energy–water nexus. The study highlights the potential of floating renewable technologies to support sustainable water management while contributing to affordable clean energy provision.