The integration of seawater desalination and wind energy technologies has allowed for the development of a directly wind-driven desalination system, with the potential to address freshwater scarcity issues without contributing to CO2 emissions. The system described in this manuscript consists of a wind turbine rotor, which employs a hydraulic transmission to directly pressurise seawater into a reverse osmosis desalination plant and a Pelton turbine generator. After building and commissioning of a 44 m hydraulic wind turbine prototype in the port of Rotterdam in the Netherlands, an experimental campaign was conducted to evaluate the operational range and performance of the hydraulic system. A combination of hardware-in-the-loop tests where used to get insight into the behaviour of the integrated system. The control philosophies used for automatic operation and safety of the system are compared and discussed, as well as the system's behaviour in response to different wind conditions using dummy elements to replace the desalination module. Technical challenges and achievements of commissioning and testing the system are also described, along with lessons learned.

Desalination is a well-established technology used all over the world to mitigate freshwater scarcity. Wind-powered reverse osmosis plants are one of the most promising alternatives for renewable energy desalination, particularly for coastal areas and islands. Wind energy can satisfy the high energy consumption of desalination while reducing costs and CO2 emissions. However, the mismatch between the intermittent availability of the wind resource and the desalination’s power demand makes the integration between the two technologies critical. This paper presents a review of wind-powered desalination systems, focusing on the existing topologies and technological advances. An overview of the advantages and disadvantages are analysed based on the theoretical and experimental cases available in the scientific literature. The goal of this work is to show the current status of wind-powered desalination and to present the technical challenges that need to be overcome in order to ensure a sustainable freshwater source.

The integration of wind energy to desalinate seawater can address the freshwater scarcity issue and alleviate the environmental impact of desalination. This paper presents the use of the Delft Offshore Turbine, an unconventional wind turbine with hydraulic transmission which can be used to directly drive a seawater reverse osmosis desalination process and to produce electricity with a Pelton turbine. A steady-state model is used to identify the potential regions at which it is possible to operate the system and to propose a system settings for maximising water production. The results show that the proposed system provides up to 300 kW of electricity and can desalinate up to 25 m³/h, at rated operating conditions.

Desalination of seawater from renewable energy sources is without doubt an appealing solution to face water scarcity issues in coastal areas. In particular, tidal energy technologies offer high potential to be integrated with existing desalination technologies. This paper contributes to the idea of using a horizontal axis tidal turbine for direct driven reverse-osmosis seawater desalination without intermediate electrical power conversion. In combination with a positive displacement pump and RO membranes, a back-pressure valve is employed at the brine exit to induce a suitable pressure in the system while keeping a variable speed operation of the rotor. A time-domain numerical model is used to simulate and compare the dynamic response of a passive and an active controlled valve configuration. Intermediate results are given for a 300 kW system under turbulent current conditions.

The integration of renewable energy sources to power seawater desalination is crucial to mitigate CO2 emissions and to face the increasing challenges that are stressing fresh water resources depletion. In particular wind energy is one of the most cost-effective forms of renewable energy with a high potential to reduce the seawater desalination's environmental impact. While most applications are aimed at using conventional wind technologies to produce the electricity required by the desalination processes, wind turbines with hydraulic transmission can bring new opportunities to avoid the multiple energy conversion steps and make fresh water production from wind energy more simple and cost-effective. This paper elaborates on two potential configurations, numerical modelling and possible control strategies which are able to directly combine a horizontal axis wind turbine rotor, a hydraulic transmission and a seawater reverse osmosis (SWRO) desalination unit. The integration of an ideal pressure exchanger as energy recovery devices (ERD) to increase the operating efficiency of the SWRO unit is analysed. Results are shown for the most relevant operating conditions of the integrated system in terms of wind speeds, pressures, brine salinity and fresh water productions. Intermediate results are also shown for the dynamic analysis and simulation of the wind powered direct-driven SWRO system subject to turbulent wind speed conditions.