Techno-economic and life cycle analysis of coupled reverse-osmosis hybrid renewable energy systems in 634 Philippine off-grid islands

The energy and water crisis is a major barrier for the economic development of off-grid islands, such as in the Philippines. Off-grid islands are typically dependent on diesel generators for electricity, and islands without reliable clean water sources resort to importation from mainland, which leads to high energy and water costs for island residents. This work proposes reverse osmosis coupled with hybrid renewable energy systems (RO-HRES) for Philippine off-grid islands to address the energy-water nexus crisis on a national level. The 634 Philippine off-grid islands considered in this work was further categorized into four island sizes (Large, Medium, Small, and Very Small) based on the peak load of each island. The RO-HRES components were sized using the Island Systems LCOE min Algorithm (ISLA) software, an in-house energy systems modeling tool. It was determined that larger islands are able to accommodate higher RE penetration, while smaller islands remain mostly diesel dependent. This results to average LCOE values for large islands of 0.234 USD/kWh compared to an average LCOE value of 0.316 USD/kWh for very small islands, but the LCOW of all islands sizes are similar in values. However, the capital costs of desalination technologies are still too high for off-grid island applications. Additionally, a life-cycle analysis (LCA) of the generated component sizes were performed to assess the environmental and health impacts of RO-HRES for off-grid islands. The high diesel dependence of very small islands, and wind turbines for large islands have been determined to have significant environmental impact. The findings in this study should encourage technology manufacturers to figure out how to drive down technology costs to allow the cost-effective deployment of desalination technology in Philippine off-grid islands. Meanwhile, policy makers should also make an effort to author new laws that will promote RO-HRES utilization in the country. • Modeled reverse osmosis with hybrid renewable systems (RO-HRES) for off-grid islands in the Philippines. • Conducted techno-economic and life cycle environmental impact assessments. • Larger islands allow more renewable energy use; smaller islands remain diesel-reliant. • Larger islands have lower LCOE; LCOW is similar across island sizes. • Diesel reliance on smaller islands harms health, ecosystem quality, and resource availability.