Renewable energy powered membrane technology: A review of the reliability of photovoltaic-powered membrane system components for brackish water desalination

Highlights: • Review of photovoltaic-powered membrane systems for brackish water desalination. • 20-year lifetime for small-scale systems (= lowest cost for water) possible via: • 1) Smart component selection based operating range, reliability and lifetime. • 2) System design optimized to enhance performance under fluctuating conditions. • 3) Correct choice of membranes as well as system operation and maintenance strategy. -- Abstract: Photovoltaic-powered membrane filtration (PV-membrane) systems are of interest for the provision of clean drinking water in small communities, especially in remote areas. In order to deliver clean water at the lowest cost over the lifetime of the system, a reliable and robust design is paramount. This paper provides a comprehensive review of the operating range and reliability of all components of a small-scale PV-membrane system for brackish water desalination. The failure and degradation modes, as well as lifetime and robustness issues associated with field operation are discussed and best-practice recommendations made. The outcomes of this paper suggest that a small-scale (power rating <1.5 kW) PV-membrane system – based on a helical rotor pump driven by a direct-current brushless motor and powered by silicon photovoltaic modules – may achieve a lifetime of 20 years, while operating with a specific energy consumption of 1.5–3 kWh/m³. Possible methods for mitigating the effects of membrane fouling and damage are also discussed. To maximize membrane lifetime, such systems ought to be operated with a recovery of less than 30% and limit the rate of change of pressure (induced by fluctuations in solar irradiance) to less than 0.7 bar/s. The analysis is useful for identifying the optimal combination of components, system operation and possible reliability improvements. The investigation into component and system failures allows the weakest links to be avoided and enable the optimization of future systems. This review is intended as valuable reference for engineers engaged in the field of renewable-energy-powered membrane filtration technologies.