Hybrid Photovoltaic-Thermal Solar System for Brackish Water Reverse Osmosis

This paper presents a comparison between traditional flat plate solar thermal collector systems and solar photovoltaic (PV) heat pump systems. The purpose of this analysis was to determine whether or not heat pump technology has matured to the point that a solar PV system paired with a heat pump could outperform a traditional solar thermal flat plate collector system. To this end, two systems with identical panel footprints of 7.6 m2 (82 ft2) were modelled and analyzed at four different locations being Los Angeles CA, Phoenix AZ, Seattle WA, and Denver CO. The expected energy production and Levelized Cost of Energy (LCOE) for both systems at these locations were determined. The solar fraction for the solar thermal collector systems and PV heat pump systems at the four locations studied were found to be f = 0.44 and f = 0.99 in Los Angeles, f = 0.44 and f = 1.00 in Phoenix, f = 0.21 and f = 0.62 in Seattle, and f = 0.34 and f = 0.90 in Denver. As such, it is evident that the solar PV heat pump systems produced more thermal energy than the solar thermal collectors at all locations tested. The LCOE for the solar thermal collector systems and solar PV heat pump systems at each location were found to be 48.42 ¢/kWh and 36.57 ¢/kWh at Los Angeles, 55.37 ¢/kWh and 36.13 ¢/kWh at Phoenix, 81.47 ¢/kWh and 97.29 ¢/kWh at Seattle, and 52.27 ¢/kWh and 67.50 ¢/kWh at Denver. From these values, it can be seen that the solar PV heat pump systems have a lower LCOE in the warmer climates where ground source heat pumps are not needed but have slightly higher LCOE values in cooler climates where they are. As such, this study has found that solar PV heat pump systems have matured enough to outperform solar thermal flat plate collectors in most situations.

With a reverse osmosis (RO) desalination plant designed to satisfy only the contracted-for water supply, the water company would be missing out on potential benefits that could have been obtained selling water in periods of high demand. On the other hand, sizing the RO desalination plant to produce water to satisfy peak demand means incurring additional costs as well as having the plant partially idle during periods of average or low demand. A model was developed using Excel macros to perform dynamic programming to optimize the capacity expansion of an RO desalination plant. The objective function is to maximize the present value of the total net benefits over the lifetime of the RO desalination plant. The model can be used to test different scenarios to capture time-variant tourism demand and price uncertainties on investment decisions. This study focuses on tourism dominated arid coastal regions, using Sharm El Sheikh (Sharm) in South Sinai, Egypt, as an example.19 RO plants in Sharm were surveyed and data were collected including unit production costs, O&M costs, energy consumption rates, contracted-for water supply, and utilization. Unit production cost of an RO desalination plant varies according to the degree of operation of the plant. This fact has to be taken into consideration when calculating the costs of RO desalination and when deciding on the plant capacity in order to maximize the total net benefit. Using the collected data, cost functions were developed for O&M costs as a function of utilization and plant capacity. The cost model calculated similar values to the actual total net benefit for one of the surveyed RO plant taken as an example. Using the optimization model, the maximum total net benefit is obtained with a smaller installed capacity than the actual case. A modified pricing structure is suggested in the paper that ties the water selling price to consumption in an effort to reduce demand in excess of contracted-for water supply aiding the water company to fulfill its contractual commitments to all users. However, price elasticity has to be taken into consideration to determine the impact of price change on water demand.

The effects of types of collector systems, operation-control methods, and locations in the world on thermal performance of solar thermal collector systems and cost to produce required amount of 90°C-hot water were studied through numerical simulations. Also performance of a hybrid photovoltaic thermal (PVT) collector system was examined. Calculation results showed that the costs for all solar thermal collector systems were much less than that without solar thermal collector system. Effect of the locations in the word on the cost was large. Total energy efficiency and exergy efficiency of PVT system were lower than those of the solar thermal collector system. The cost for PVT system was higher than that for the solar thermal collector system.

A theoretical analysis on upgrading desalination plants with low-salt-rejection reverse osmosis

Capital cost estimation of RO plants: GCC countries versus southern Europe

Energy response of a mono-axis tracked solar thermal collector with vacuum tubes

Modeling, control, and dynamic performance analysis of a reverse osmosis desalination plant integrated within hybrid energy systems

Today, reverse osmosis membranes are the leading technology for new desalination installations, however, a challenge facing widespread application of RO technology is membrane fouling. In the present study, we used an environmentally friendly green inhibitor as anti-scaling and anti-biofouling in reverse osmosis (RO) desalination plants. The influence of Sargassum sp., Corallina mediterranea, and Avicennia marina on RO membrane mineral scaling was evaluated using gypsum as a model scalant. Antibacterial properties for three marine extracts from Sargassum sp., C. mediterranea, and Avicennia marina were investigated with Gram-positive bacteria (ArthrobactersulfureusYACS14, Staphylococcus aureus) and Gram-negative bacteria (VibrioanguillarumMVM425, Escherichia coli). The antimicrobial results were detected for the two selected extracts as the most potent extracts (ethyl acetate, methanol crude extracts of the Avicennia marina leaves). Data showed that ratios of 3 and 5% recorded the highest suppression percentages (100%) for all tested bacteria including bacterial community collected from Eastern Harbor. On the other side, data confirmed that the anti-scalant properties by 100 ppm of Avicennia marina leave extract giving 85% of scale inhibition. The effect of Avicennia marina leaves extract for calcium sulfate dihydrate (gypsum) scaling on selected reverse osmosis (RO) membrane surfaces was investigated. The effect of different concentrations of Avicennia marina leaves extract was observed in the extent of surface scale coverage and surface crystal size among the membrane studied.

To solve the problems of high specific energy consumption and excessive harmful ions in the water production of a small reverse osmosis (RO) plant, a desalination system coupling RO and membrane capacitive deionization (MCDI) is proposed in this study. Aiming at producing two cubic meters per day of fresh water with a salt concentration of less than 280 mg L−1, parameter matching optimization was carried out on two desalination system schemes of one-stage two-section RO and one-stage three-section RO coupled with MCDI. The results were compared with the parameter matching optimization results of the one-stage one-section RO and the one-stage two-section pure RO desalination system. The results show that compared with the pure RO desalination mode, the seawater desalination mode coupled with RO and MCDI reduces the specific energy consumption under the same effluent salt concentration. Moreover, it decreases the feed water pressure in front of the RO membrane, which can reduce the standard of high-pressure pump in a small seawater desalination plant. The energy consumption of the one-stage three-section RO and MCDI coupling system is lower than that of the one- stage two-section RO and MCDI coupling system, and the feed water pressure is also lower.

This article reviews the design of solar phase-change energy storage systems and their applications in residential buildings. The solar thermal collection system has high heat collection efficiency, no pollution, and it is also widely used in the field of building heating. In order to improve the efficiency of the solar collector system, the researchers found that integrating phase-change materials (PCMs) into the solar thermal collector system can achieve this goal, but there will be a problem of PCM leakage. Some researchers have solved this problem by microencapsulating PCMs, the thermal conductivity and energy storage efficiency of the PCMs after microencapsulation will be greatly affected. Adjusting the solar collector to an appropriate inclination angle can achieve the highest heat collection efficiency. Choosing the PCM in the appropriate temperature zone can improve the system efficiency. For the separated solar collector system, the parts that need to be considered include the type of heat exchanger, the structure of the energy storage heat exchanger, the shape of the heat exchanger fins, the type of solar collector, and so on. All in all, coupling PCM into the solar collector system can improve energy efficiency reduce carbon emissions and have good economics, the maximum internal rate of return of solar collectors integrated with PCMs in residential and industrial applications is 22% and 17.2%.

Recently, the reverse osmosis (RO) process is widely used in the field of desalinating brackish water and seawater to produce freshwater, but the disadvantage of using this technology is the increase in the rates of electrical energy consumption necessary to manage these units. To reduce the rates of electrical energy consumption in RO desalination plants, geothermal energy and photovoltaic/thermal panels were used as preheating units to heat the feed water before entering RO desalination plants. The proposed system in this study consists of an RO desalination plant with an energy recovery device, photovoltaic/thermal panels, and a geothermal energy extraction unit. To evaluate the system performance, three incorporated models were studied and validated by previous experimental data. The results indicated that incorporating the geothermal energy and photovoltaic/thermal panels with the RO desalination plants has positive effects in terms of increasing productivity and reducing the rates of specific power consumption in RO desalination plants. The average saving in the specific power consumption for utilizing the thermal recovery system of PV panels and geothermal energy as preheating units reached 29.1% and 40.75% for the treatment of seawater and brackish water, respectively. Additionally, the economic feasibility showed the saving in the cost of freshwater produced from the RO desalination plants for incorporating both geothermal energy and photovoltaic panels with a thermal recovery system with reverse osmosis desalination plants of up to 39.6%.

Existing and the future planned desalination facilities in the Gaza Strip of Palestine and their socio-economic and environmental impact

the adaption of renewable energy (RE) in electric systems (ESs) involves many technical challenges when its share exceeds certain levels. Various strategies are used to manage these challenges. The reverse osmosis (RO) desalination plants can play a significant role in RE integration because of their high energy consumption and flexibility of operation. This paper investigates how RO desalination plants can help in integrating RE resources in ESs. First, the impact of different levels of RE penetration on IEEE 30-bus system was studied in terms of voltage profile. Then, the adaption of an RO plant in the system as a flexible load was introduced to reduce the effects of RE penetration. The consumption of RO plant was decreased during the absence of RE and increased at the midday hours to absorb the surplus power generated by RE. This prevented the ES voltage profile to fall below the permissible limits. The results showed that, the coordination between RO plants and ESs operation had a significant positive role.

Thermodynamic analysis of a solar thermal facilitated membrane seawater desalination process


 Seawater intake and its treatments are one of the main upstream processes of every seawater desalination plant (RO, ED, MSF, MED). However, the process has turned out to be of utmost importance for reverse osmosis (RO) desalination plant. It is to be sure that sufficient and steady flow and quality of water is available to the RO desalination plant. Prior to RO feed water, the seawater intake pre-treatment process has to be tailored and the quality of seawater intake to be treated either subsurface intake or open surface intakes, particularly when treating open surface intakes seawater (OSIS) with exceedingly unpredictable quality. According to the well-established membrane manufacturer and supplier, the RO membrane warranty and guarantee are depended on seawater intake quality and its pre-treatment. Thus, the current state-of-the-art RO membranes life and performance success for desalination processing depend upon OSIS pre-treatment processing techniques. This article is emphasizing an overview on recent OSIS and its pre-treatment techniques for RO desalination plant.