A hybrid renewable energy system as a potential energy source for water desalination using reverse osmosis: A review

Optimal design of a hybrid solar-wind power to drive a small-size reverse osmosis desalination plant

The transition from fossil fuels to renewable energy sources is imperative to mitigate climate change and achieve sustainable development goals (SGDs). Hydrogen, as a clean energy carrier, holds great potential for decarbonizing various sectors, yet its production remains predominantly reliant on fossil fuels. This study explores a novel approach to sustainable hydrogen production by integrating offshore wind energy with reverse osmosis (RO) desalination technology. The proposed configuration harnesses offshore wind power to energize both a RO desalination system and water electrolysis unit. Initially, the wind energy powers the RO desalination process, purifying seawater, and then desalinated water is directed to water electrolysis system for generating green hydrogen directly from seawater. The resulting renewable hydrogen holds potential for diverse applications, including marine industries, and can be transported onshore as needed. The RO system is configured to treat 20 kg s−1 of seawater with a salinity of 35 000 ppm, aiming for a high recovery ratio and reduced freshwater salinity. A pressure exchanger (PX) is integrated to recover energy from high‐pressure brine stream and transfer it to the low‐pressure feed water, thus reducing the overall energy consumption of the RO process. The concentrated brine extracted from RO desalination is proposed to be utilized for the production of sodium hydroxide that can further pretreat incoming seawater and enhance the effectiveness of the filtration process by mitigating membrane fouling. This pressure exchanger increases the energy efficiency of the RO system from 63.1% to 64.0% and exergetic efficiency from 13.9% to 18.2% increasing the overall first and second law efficiencies to 37.9% and 33.5%. By leveraging offshore wind power to drive RO desalination systems, this research not only addresses freshwater scarcity but also facilitates green hydrogen generation, contributing to the advancement of renewable energy solutions and fostering environmental sustainability.

Due to the rising cost of fossil fuels and environmental pollution, renewable energy (RE) resources are currently being used as alternatives. To reduce the high dependence of RE resources on the change of weather conditions, a hybrid renewable energy system (HRES) is introduced in this research, especially for an isolated microgrid. In HRES, solar and wind energies are the primary energy resources while the battery and fuel cells (FCs) are considered as the storage systems that supply energy in case of insufficiency. Moreover, a diesel generator is adopted as a back-up system to fulfill the load demand in the event of a power shortage. This study focuses on the development of HRES with the combination of battery and hydrogen FCs. Three major parts were considered including optimal sizing, maximum power point tracking (MPPT) control, and the energy management system (EMS). Recent developments and achievements in the fields of machine learning (ML) and reinforcement learning (RL) have led to new challenges and opportunities for HRES development. Firstly, the optimal sizing of the hybrid renewable hydrogen energy system was defined based on the Hybrid Optimization Model for Multiple Energy Resources (HOMER) software for the case study in an island in the Philippines. According to the assessment of EMS and MPPT control of HRES, it can be concluded that RL is one of the most emerging optimal control solutions. Finally, a hybrid perturbation and observation (P&O) and Q-learning (h-POQL) MPPT was proposed for a photovoltaic (PV) system. It was conducted and validated through the simulation in MATLAB/Simulink. The results show that it showed better performance in comparison to the P&O method.

Investigation into economical desalination using optimized hybrid renewable energy system

The optimal configuration of hybrid renewable energy (RE) system is useful for ensuring enough power is generated to meet the demand with reliable and cost effective manner. This is an alternative environmental friendly approach to reduce the use of diesel generators and cost of power generation. It is also a step to support the government's intention to move towards green energy. In this paper, the hybrid of micro-hydro, solar, diesel generator, power converter and battery as back-up supply are the basic components considered in the optimal sizing and operation of hybrid RE system. Based on the domestic load at Kampung Pasir Raja, Dungun, the proposed hybrid RE system is determined and analyzed by using the Hybrid Optimization Model for Electrical Renewables (HOMER) software. This paper discusses thoroughly on the best combination of hybrid RE system determined based on the lowest Total Net Present Cost (TNPC). Furthermore, the results have shown that the TNPC produced by the hybrid RE system is better than the conventional energy that is the diesel generator.

Water scarcity represents one of the most critical environmental and economic challenges worldwide, especially in arid and semi-arid regions lacking access to reliable freshwater sources. In response, seawater desalination has emerged as a strategic solution to ensure a sustainable and secure supply of potable water for various applications. Among desalination technologies, Reverse Osmosis (RO) stands out for its high efficiency and widespread adoption, primarily due to its relatively low specific energy consumption compared to thermal-based methods. However, high operational costs particularly those related to energy consumption remain a barrier, as most conventional desalination plants rely on fossil fuels, contributing significantly to greenhouse gas emissions and environmental degradation. In this context, integrating renewable energy sources, specifically solar photovoltaic (PV) and wind energy, offers a viable pathway to reduce operational expenditures and minimize environmental impact. Several studies have demonstrated that hybrid renewable energy systems can enhance the sustainability and energy autonomy of desalination plants, aligning with Global Sustainable Development Goals (SDGs). This study conducts a techno-economic analysis of a Seawater Reverse Osmosis (SWRO) plant located in Al Wajh, Saudi Arabia. Detailed Capital expenditures (CAPEX) and Operational Expenditures (OPEX) were estimated for both conventional electricity-based operation and for configurations utilizing solar and wind energy in the same location. An energy simulation model was conducted to determine the optimal number of wind turbines required to maximize energy efficiency while minimizing excess power generation. The analysis revealed that the SWRO powered by renewable energy achieved an energy efficiency of 99%, compared to its conventional electricity-powered counterpart, with an energy surplus of no more than 4%. CAPEX and OPEX cost projections were calculated for both scenarios: conventional grid electricity and renewable energy sources. The findings indicated that the unit production cost per cubic meter of the SWRO plant was 0.59–0.76 $/m3 in the case of grid electricity, whereas it was 0.74–1.12 $/m3 under renewable energy integration. This cost disparity is primarily attributed to the higher CAPEX required for the renewable energy-powered SWRO system, which amounted to 0.28–0.36 $/m3, in contrast to a significantly lower CAPEX of only 0.06–0.09 $/m3 for the electricity-based SWRO configuration. Moreover, artificial intelligence (AI) was employed to support the results and forecast future water demand based on regional climate conditions and consumption patterns. The study concludes with a set of recommendations aimed at optimizing the integration of renewable energy technologies into desalination systems to enhance long-term economic and environmental sustainability.

The key drivers for increasing the use of renewable energy are large and un-explored potential, a gap between demand and supply to increase in potency, and environment concerns. The maximum available potential at all sites are majorly wind and solar energy, but due to the high unpredictable nature of wind, designing a system based on only wind energy may not be technically viable, therefore, a combination of renewable energy sources is fascinating researchers to design and implement the power system in a developing country leads the development of the hybrid energy system. Research and development in the field of solar, wind other renewable energy sources will be the future substitute in meeting the demand and supply gap of power. This paper presents a review of work done by various researchers in the area of pre-feasibility, unit sizing, modelling, and operation and control of various hybrid renewable energy systems.

The Southwest Maluku region in eastern Indonesia is considered a frontier, outermost and underdeveloped region. Its inhabitants live on isolated islands, including the residents of Mahaleta Village, where only 9.4% of the community have limited access to electricity. This study aimed to design an economically feasible hybrid renewable energy (RE) system based on solar and wind energy to integrate with the productive activities of the village. The study developed conceptual schemes to meet the demand for electricity from the residential, community, commercial and productive sectors of the village. The analysis was performed using a techno-economic approach. The hybrid system was designed using the HOMER Pro optimization function, and cold-storage and dryer systems were designed to support related productive activities. The optimized design of the hybrid RE system comprised 271.62 kW of solar photovoltaics, 80 kW of wind turbines and a 1-MWh lead–acid battery. We found that the hybrid RE system would only be economically feasible with a full-grant incentive and an electricity tariff of $0.0808/kWh. However, the productive activity schemes were all economically feasible, with a cold-storage cost of $0.035/kg and a drying cost of $0.082/kg. Integrating the hybrid RE system with productive activities can improve the economic feasibility of the energy system and create more jobs as well as increase income for the local community.

Energy is pivotal for the economic progress and societal advancement of any nation. To minimize reliance on imported fuels and address the increasing gap between energy demand and supply, it is imperative to optimize indigenous energy resources, while considering economic, environmental, and social constraints. The surge in population has exacerbated the energy crisis, widening the disparity between demand and supply. Depletion of conventional energy sources has led to an energy supply shortfall. While renewable energy sources (RES) offer promise in the energy sector, their standalone operation is hindered by their intermittent nature, resulting in interruptions in power supply to loads. To ensure stable and reliable power supply, hybrid combinations of renewable energy sources have been adopted. The design of a hybrid wind-solar Photovoltaic (SPV) system for power generation, targeting domestic households in remote areas disconnected from the grid, has been proposed. Such hybrid systems operate either in isolated mode or in grid-connected mode via power electronics interfaces, augmenting reliability and ensuring continuous power supply. Introducing a Hybrid Renewable Energy System (HRES) aims to enhance the productivity and operability of individual renewable energy systems. Extensive technological investigations have explored various approaches, including linear programming and a novel optimum control strategy incorporating PID controllers, fuzzy logic controllers, AI, and optimal torque with Maximum Power Point Tracking (MPPT) techniques. The developed novel optimum control strategy facilitates the coordinated operation of diverse devices and power interface circuitries, with the primary objective of ensuring continuous power supply. Simulation studies have evaluated system performance under different scenarios, including varying solar radiation, temperature, air conditions, and battery charge/discharge conditions. Results indicate variable power generation and affirm the efficacy of the integrated system and control strategies in real-time installations. The investigation reveals that the developed novel optimum control strategy significantly enhances the performance of standalone hybrid wind-SPV systems. The hybrid system, when integrated with controllers, exhibits improved output power and ensures continuous power delivery, thereby enhancing overall system efficiency and reliability. Such systems are indispensable in isolated regions where grid connectivity is unavailable, ensuring secure power generation by intelligently harnessing diverse energy sources.

The archipelagic geography of the Philippines has resulted in thousands of inhabited off grid islands wherein energy and water access are hindered. Electricity in these islands is provided by diesel generators, while water is obtained from rainwater, groundwater, or imports from the mainland. As an alternative to these costly and unsustainable sources, hybrid renewable energy systems (HRES) coupled with reverse osmosis (RO) desalination has been investigated for the cogeneration of electricity and water. In this work, the techno economic potential of coupled RO HRES in selected off grid areas in the Philippines was evaluated. Solar photovoltaics, wind turbines, lithium ion batteries, and diesel generators were considered as HRES components. Dumaran Island and Bantayan Island were chosen as case studies because both islands have faced electricity and water supply concerns. Moreover, these islands present different use cases as Dumaran Island is mainly residential while Bantayan Island has a growing resort industry. Three scenarios were considered in this work to analyze the transition from the status quo to the energy water system: diesel only, HRES, and RO HRES. The islands and scenarios were modeled using the Island Systems LCOEmin Algorithm, an in house energy systems modeling tool written in Python 3. Transition from the diesel only system to HRES decreased the system costs by an average of 15.1 % in both islands. However, the installation of RO was primarily beneficial for the resort island wherein electricity costs increased by only 0.8 % from the HRES scenario and water costs were 80 % lower than current rates in surrounding islands. In contrast, RO deployment in the residential island raised electricity prices by 10.8 %.

Remote island communities are mostly energized by diesel generation. Although fossil fuel provides on-demand power, its application on these type of islands has its drawback in terms of operations and logistics. Today, Renewable Energy technologies is becoming cost-competitive with fossil fuels and can be deployed on large scales. For these islands community’s power demand, renewable energy is an option, but unfortunately, it cannot cover the demands at all times. In such cases, a hybrid energy system is recommended. This study, focused on the performance analysis of different combinations of Diesel – RE hybrid system in terms of the lowest cost of energy, renewable energy fraction, and carbon emission reduction. The analysis has been performed using HOMER Pro, in which for a Diesel – RE hybrid system in Cuyo Island, the most suitable is the Diesel/Wind Hybrid Electrical System, which gives the lowest cost of energy of about $0.113/kWh, renewable energy fraction of about 72.8% and emission reduction of 71.8%. This system can support additional future load as much as 88.6% of the existing load demand and has a significant impact on mitigating carbon footprint. Wind Turbine and Solar PV array’s Levelized Cost of Energy (LCOE) are $ 0.029/kWh and $ 0.053/kWh respectively. With a 40-year wave hindcast data from MetOceanView, Wave Energy Converter (WEC) performance was also assessed using the Hydro module of Homer Pro Software. Assessment has been made with single and multi – WEC combined with diesel and other RE’s. Results show that the LCOE for WEC is about $0.66/kWh, which is within the range of $0.20 - $0.90/kWh levelized cost for wave energy at present. With the continues evolution of RE Technologies and cost – competitiveness is becoming less of an issue, electrifying isolated island communities through hybrid electrical system will be more feasible in the future.

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