A methodology to obtain the performance curves of windmills associated with piston pumps: application in water desalination systems by reverse osmosis

Nowadays, shortage of the water resources is a global issue. Water desalination is a solution that can be used to solve the water shortage problem. Several methods have been proposed for water desalination and are categorized to membrane and non-membrane procedures. The most popular membrane processes are electrodialysis (ED) and reverse osmosis (RO); in contrast, the most popular non- membrane processes are capacitive deionization (CDI) and distillation. All water desalination procedures need energy supplies. The solar and Photovoltaic (PV) energy is potentially a desirable green energy supply for water desalination especially for non-residential areas where the grid is not available. In areas such as deserts and offshore stations, the PV solar energy is a practical and cost effective solution for water desalination systems. Where the grid connection is available, the PV and solar desalination systems produce fewer emissions. The PV energy needs to be processed through power electronic power conditioning systems. This paper proposes the application of PV power and solar energy to supply the water desalination systems.

Fresh water production is one of the main concerns in the new century. Population grows fast and potable water resources are decreased. In the other hand energy crises would also be another issue that must be well addressed by the politicians and also scientists. Developing desalination plant with using renewable energy (particularly solar energy) is one of the important options to overcome these concerns. Thus many researchers have been working on different desalination plants to find the best conditions and to realize the most efficient performances for different cycles. Different approaches have been used to achieve the most efficient conditions or to find the optimum operation and design conditions. Some of the researchers used parametric study approach while many other adopted different conventional optimization algorithms for these tasks. The algorithms such as gradient based algorithm, genetic algorithm, search and pattern algorithm and neural network method have been used in the field of desalination. For instance; Ophir and Lokiec (2005) described the design principles of a MED plant and various energy considerations that result in an economical MED process and plant. Kamali and Mohebbinia (2007) showed that parametric study as one of the optimization methods on thermo-hydraulic data strongly helps to increase GOR value inside MED-TVC systems. Shamel and Chung (2006) used parametric study to find the optimum condition of a Reverse Osmosis (RO) system for sea water desalination. Metaiche et al (2008) developed optimization software, Desaltop, for RO system for water desalination. They used genetic algorithm to find suitable operating parameters and also to find appropriate type of membrane. Al-Shayji (1998) used neural network method for optimization of large-scale commercial desalination plants. Djebedjian et al. (2008) used genetic algorithm for optimization of a reverse osmosis desalination system. Mussati et al. (2003) used an evolutionary algorithm for the optimization of Multi Stage Flash (MSF) system. Finding the optimum conditions is a major challenge on the desalination plant studies. The plant performance depends on several different variables and constraints that need exhausting efforts to find the optimum conditions. This chapter introduces Design of Experiment (DOE) method as a statistical tool for optimization of desalination systems. Thus two different desalination plants; Multi-Effect Desalination (MED) system and solar desalination using humidification–dehumidification cycle (SDHD) have been considered to show the ability of DOE method for optimizing such systems. These both desalination plants could use the low graded heating energy sources

This paper explores the application of genetic algorithms (GA) for optimal design of reverse osmosis (RO) water desalination systems. While RO desalination is among the most cost and energy efficient methods for water desalination, optimal design of such systems is rarely an easy task. In these systems, salty water is made to flow at high pressure through vessels that contain semi-permeable membrane modules. The membranes can allow water to flow through, but prohibit the passage of salt ions. When the pressure is sufficiently high, water molecules will flow through the membranes leaving the salt ions behind and are collected in a fresh water stream. Typical system design variables for RO systems include the number and layout of the vessels and membrane modules, as well as the operating pressure and flow rate. This paper explores models for single and two-stage RO pressure vessel configurations. The number and layout of the vessels and membrane modules are regarded as discrete variables, while the operating pressures and flow rate are regarded as continuous variables. GA is applied to optimize the models for minimum overall cost of unit produced fresh water. Case studies are considered for four different water salinity concentration levels. In each of the studies, three different types of crossover are explored in the GA. While all the studied crossover types yielded satisfactory results, the crossover types that attempt to exploit design variable continuity performed slightly better, even for the discrete variables of this problem.

In this work the performance evaluation of directly driven Reverse Osmosis (RO) water desalination system by Photovoltaic (PV) arrays is investigated by a novice method. Reverse Osmosis water desalination system needs continuous supply of energy and on the other hand energy from the PV is intermittent in nature. The energy consumption of RO plant is strong function of clean water (permeate) flow rate and system pressure and they needs to be tuned to match the maximum power provided by the PV arrays. In this work a novice method to tune the RO system parameters by manipulating the position of the valve at the brine side of the RO system is proposed. A simple perturb and observe algorithm is used for automatic control of the valve position. The performance of the proposed battery less system is compared with a conventional system using PV, charge controller and battery. The proposed directly driven battery-less system provides more water per day than battery operated system.

Desalination of brackish water by using reverse osmosis (RO) system powered by solar PV has not been tried and examined in Palestine until now. This paper proposes rural village Al Maleh for erection and testing of the first PV-powered RO system. Al Maleh is highly qualified for testing of such systems since it has a lot of mineral hot water springs of about 3400 ppm salinity. Based on the climate conditions in Al Maleh, the paper presents the design of the PV-powered RO water desalination system. The obtained design results can be used for an economic feasibility study of this technology [Mahmoud, M. Techno-economic feasibility of PV-powered water desalination in Palestine. Special Case: Al Maleh Village (to be published).]. The performance of the designed system is investigated by software simulation. The obtained results show that a daily production of 1 m3 from the brackish water in Al Maleh would require about 820 peak watt of PV generator.

Current progress in integrated solar desalination systems: Prospects from coupling configurations to energy conversion and desalination processes

Handling the variability and uncertainty associated with integrating large capacities of renewable energy sources (RES) into the power grid is a challenge that is increasingly influencing the power systems operation. At the same time, the growing need for desalinated water in arid areas increases the importance of suitable energy sources for sustainable operation of water desalination plants. However, as power and water system operators have traditionally operated their systems in isolation, there is a lack of understanding of the interdependence and interactions between these two systems. This paper addresses this gap by proposing a risk-based two-stage stochastic co-optimization framework that coordinates the operation of a renewable-rich power system with the operation of grid-connected reverse-osmosis water desalination plants (RO-WDP) to minimize their combined operational costs while increasing the utilization of RES. From the power system operation standpoint, the RO-WDPs are considered as controllable demand, and the proposed model integrates the energy flexibility of RO-WDPs in the day-ahead power system operation. The proposed model considers the operational constraints of both power and water desalination systems, thus co-optimizing their operation without compromising the reliable supply of power and water to end-users, while taking into account the uncertainty of the demands and RES. Simulation results demonstrate the benefits of the proposed coordination on enhancing the power system efficiency, facilitating RES integration, and minimizing the combined operational costs of both systems while minimizing their operating risk using conditional value at risk.

Modeling and optimization of hybrid wind–solar-powered reverse osmosis water desalination system in Saudi Arabia

The Development of a Renewable-Energy-Driven Reverse Osmosis System for Water Desalination and Aquaculture Production

Hydrophilic hollow fiber membranes for water desalination by the pervaporation method

A hybrid multi effect distillation and double reverse osmosis system for most economical brackish water desalination

Reverse Osmosis (RO) is a widely used technology in Defence operations to provide clean, potable water in remote and harsh environments. The water desalination systems available with the services experience operational discontinuities, treatment of a wide range of feedwater, which results in a significant enhancement of RO membrane fouling. Herein, the impact of fouling was studied using an in-house developed high-pressure desalination system. Experiments were conducted on two types of membrane modules, one with induced fouling using underground water (MM1) and a naturally fouled membrane module due to operational discontinuities over a period of 9 months (MM2). The performance of these modules was recorded before scaling, after scaling and, after scale removal in terms of per cent salt rejection, per cent recovery, product TDS, and product flux rate. It was observed that MM1 fouled mainly due to inorganic scaling was easily regenerated using 2wt % citric acid cleaning solution, while MM2 fouled due to inorganic and biological agents was treated using tailored cleaning protocols, amongst which, sodium tripolyphosphate and sodium dodecylbenzene sulphonate mixture provided the best results. Overall, these findings underscore the necessity of proper mitigation strategies to combat fouling of RO membrane modules that are operated at a high pressure similar to commercial desalination systems.

Eco-friendly RO system for water desalination

Supervisory Predictive Control of an Integrated Wind/Solar Energy Generation and Water Desalination System

This work proposes a two-time-scale framework for the design of a supervisory predictive control system for long-term optimal management and operation of an integrated wind-solar energy generation and reverse-osmosis (RO) water desalination system. Specifically, we design the supervisory control system via model predictive control (MPC) which coordinates the wind and solar subsystems as well as a battery bank to provide enough energy to the RO subsystem. In the supervisory MPC design, a two-time-scale property of the dynamics of the integrated system is taken advantage of to improve the computational efficiency of the control problem formulation. Furthermore, optimality considerations on system operation and energy savings are taken into account via appropriate constraints in the supervisory controller formulation. Simulations are carried out to illustrate the applicability and effectiveness of the proposed supervisory predictive control design.