Energy Desalination Research Articles

Experimental and theoretical work on reverse osmosis - Dual stage pressure retarded osmosis hybrid system

Two-pass reverse osmosis desalination is a common process to treat high-salinity feed solution and provides a low-salinity permeate solution. This study investigated the significance of the energy generated by the dual-stage pressure retarded osmosis (DSPRO) from the reverse osmosis (RO) brine stream. The main components of the DSPRO-RO hybrid system are RO, pressure retarded osmosis (PRO), and energy recovery device, and their models are determined. Dymola software, using Modelica modelling language, was utilized for solving the hybrid system models. Two different flowsheets were built; the first included a two-pass RO, while the second is a hybrid of a two-pass RO (2RO)-DSPRO system. Seawater salinities of 40 and 45 g/L were the RO feed solution, and 1 g/L tertiary treated wastewater was the feed solution of the DSPRO process. The net specific energy consumption was calculated for the 2RO and 2RO-DSPRO systems for 40 and 45 g/L salinities. At a 47 % recovery rate and 40 g/L seawater salinity, the 2RO-DSPRO system was 14.7 % more energy efficient than the 2RO system. The corresponding energy saving at a 47 % recovery rate and 45 g/L seawater salinity was 17.5 %. The desalination energy for the 2RO system was between 3.25 and 3.49 kWh/m3, and for the 2RO-DSPRO system was between 2.91 and 2.97 kWh/m3. The results demonstrate the great potential of integrating the 2RO with the DSPRO to reduce desalination's energy consumption and environmental impacts.

Sponge‐Supported Reduced Graphene Oxides Enable Synergetic Photothermal and Electrothermal Conversion for Water Purification Coupling Hydrogen Peroxide Production

To address the freshwater scarcity issue and the environmental impact of wastewater disposal, herein a novel efficient strategy to enhance the performance of solar‐driven interfacial evaporation technique is developed to purify salt‐containing wastewater and seawater for sustainable clean water production. This strategy enables photovoltaic electricity to power photothermal conversion for rapidly vaporizing brine using commercial melamine sponge (MS)‐supported reduced graphene oxides (MS@rGO). The record‐high performance with an evaporation rate of 9.02 kg m−2 h−1 along with a solar‐to‐vapor efficiency of 287.4% in 7 wt% salt brine is achieved under 1 sun and optimized voltage applied. During evaporating brine, MS@rGO can also efficiently catalyze oxygen reduction for the sustainable production of H2O2 to serve as the broad‐acting disinfecting agent in the condensed water. Because applying voltages can facilitate the movement of salt ions in brine, the presented system is endowed with excellent salt‐resistance and superior ability of extracting photogenerated electrons, significantly improving the energy utilization efficiency. Therefore, this design provides a new way for highly efficiently applying solar energy in saline wastewater purification and seawater desalination with low cost.

Development of a Model for the Implementation of the Circular Economy in Desert Coastal Regions

Food production is the main challenge for developing arid regions due to the restricted access to fresh water. This study combines the environmental know-how of two coastal desert regions on the American continent with similar geographical characteristics to propose a general model for a circular economy in stressed environmental conditions. The Atacama Desert, located in Chile, is the driest place on Earth. Due to the lack of rainfall in decades, the possibility of growing food is almost impossible. The Desert of Sonora, in the northwest of Mexico, is known for its extreme aridity and temperatures over 50 °C in summer. Both deserts have continuously growing cities ranging from 400,000 to 900,000 inhabitants, where access to and management of freshwater represents an issue. A circular economy model was developed. Critical parameters for this model considered: the utilisation of solar energy for water desalination and energy production, integrated with hydroponic farming and water dosing with hydrogels for food production; microalgae for biofuels; seaweed for biochemicals; anaerobic digestion for organic waste management and nutrient recovery from wastewater sludge treatment. Regional policies and governance are needed to incentivise the adoption of circular economy models.

Biomass hydrogels combined with carbon nanotubes for water purification via efficient and continuous solar-driven steam generation

Solar vapor generation is a promising, environmentally friendly solution for water purification. The development and design of new materials and supporting devices for efficient energy conversion and clean water production are essential for the practical application of solar-driven desalination and water purification. In this study, an environmentally friendly and economical biomass hydrogel-based solar evaporator with a controllable shape was developed in a simple method by integrating carbon nanotubes (CNTs) into a sodium alginate (SA) hydrogel network. The evaporator had a high solar absorption rate (94.3%) and satisfactory hydrophilicity and could effectively avoid salt crystallization during the desalination process. This study took advantage of the aforementioned merits, and a high evaporation rate of 1.699 kg m-2 h-1 and a conversion efficiency of 86% were achieved under 1.0 sun irradiation. The evaporator could efficiently remove Na+, K+, Ca2+, and Mg2+ from seawater with a removal rate of up to 99.3% and a good decolorization effect on methylene blue (MB) and methyl orange (MO) dye wastewater, whose colour could be completely removed. This study provides a simple, practical, and economical method to prepare hydrogel-based evaporators that utilize abundant solar energy for large-scale desalination and wastewater treatment.

Experimental comparison of solar thermal desalination systems based on energy, exergy and economic (3‐E) analysis

AbstractWith rapid increase in human population, the demand of fresh water has been increased significantly and the world will encounter enormous water crisis by 2040. The sea contains nearly 97% of available water on earth. To fulfill the demand of fresh water, desalination of sea water can be best solution. As desalination process can be performed by using low grade energy, the use of solar energy for desalination is very popular. The most popular solar thermal desalination system is conventional solar still but its productivity is very low. In the present study, a new desalination system based on evacuated tube collectors (ETC) is developed and its performance is compared with conventional solar still experimentally. The present system consists of 15 evacuated tubes, an insulated storage tank, a heat exchanger, a condenser, and a thermic fluid as working medium. The performance of both systems is compared on the basis of daily productivity, energy and exergy efficiency, and economic viability. It is observed that the ETC‐based desalination system performed better as compared to the solar still. The average energy and exergy efficiency, productivity and produced fresh water cost of desalination systems based on ETC and conventional solar still are 43.74%, 9.52%, 4.2 L/m2/day, 0.022 $/L and 19.23%, 1.4%, 1.975 L/m2/day, 0.024 $/L respectively. Further, the pay‐back time for ETC based desalination system is also less (104 days) as compared to solar still (113 days).

Smart Meters Rollout in Jordan: Opportunities, Business Models, Challenges, and Recommendations

Jordan's energy demand is growing steadily due to many factors ranging from the growing population, to the needed energy for heating, cooling, desalination, and industry (Azzuni et al., 2020). EMRC has stated a new electricity tariff starting from April 2022. The high cost of electricity bill in Jordan with fixed tariff has resulted the need to have a dynamic tariff to transform energy use that lead to demand reductions, a shift in peak demand, a better management of distribution networks, in addition to reductions in operation costs. A full transition towards smart meters in Jordan is one of the main pillars to achieve a compatible smart grid system that will be a great solution to sustain the energy security. Also, it will lead to flatness the demand profile which will have economic consequences by reducing the cost of electricity generation. The current status of smart meters’ rollout, the optimal business model, challenges, and awareness towards energy strategies and smart meters deployment in Jordan have been investigated. It has been found that the optimal business model for the Jordanian market is a hybrid model of DGC and EaaS models. Also, a set of opportunities and recommendations have been concluded.

Performance and Lifetime of Battery Desalination Cells Based on Nickel Hexacyanoferrate

Prussian blue analogs, e.g., nickel hexacyanoferrate, NiFe(CN)6 or NiHCF, are promising candidates as low-cost and high-rate intercalation materials for secondary batteries.1–4 Recently, this material class has been shown to possess tremendous potential for a novel energy-efficient water desalination approach.5–8 Rising water demands are exacerbating water scarcity in many world regions. It is estimated that 60% of the global population will face severe water scarcity by 2025.9 The growing water demand necessitates new desalination technologies with high energy efficiency, low capital and operating cost and high freshwater output. In this work, we assess the performance and lifetime of electrochemical water desalination cells based on sodium intercalation into nickel hexacyanoferrate.10–12 The battery desalination cells feature a symmetric design, with two NiHCF electrodes at opposite state-of-charge (SOC), capable of intercalating Na+-ions into their crystal structure. The electrodes are separated by an anion exchange membrane, a porous functionalized polyether ether ketone (PEEK) membrane, that only permits negatively charged ions, e.g., Cl--ions, to pass. Two feed water streams with 20 mM NaCl enter the symmetric cell on either side (see Figure 1a). During charge of the symmetric cell, incoming Na+-ions are removed from one water stream and intercalated into the NiHCF electrode at low SOC. Simultaneously, Na+-ions are deintercalated from the opposite NiHCF electrode at high SOC. In order to maintain charge neutrality, Cl--ions cross the anion exchange membrane. Thus, during every charge/discharge cycle, one water stream is desalinated forming a freshwater stream, while the other is enriched in NaCl forming a brine waste stream (see Figure 1b).In order to quantify performance and lifetime of the novel battery-type water desalination cells, we define and measure objective metrics. We see that energy consumption (Wh/l) and productivity (l/h/m2) of NiHCF/NiHCF cells are superior to cells based on membrane capacity deionization (mCDI). Stable charge/discharge cycling of NiHCF/NiHCF cells can be achieved for over 500 cycles with NaCl feed water, but rapid aging is observed with CaCl2 feeds. Synchrotron-based characterization of NiHCF/NiHCF cells is used to elucidate the reason for capacity fade. X-ray absorption spectroscopy and X-ray fluorescence spectroscopy reveal Fe dissolution from the NiHCF active material as a primary aging mode with CaCl2 water feeds. References Wessells, C. D., Peddada, S. V., Huggins, R. A. & Cui, Y. Nickel hexacyanoferrate nanoparticle electrodes for aqueous sodium and potassium ion batteries. Nano Lett. 11, 5421–5425 (2011).Wessells, C. D. et al. Tunable reaction potentials in open framework nanoparticle battery electrodes for grid-scale energy storage. ACS Nano 6, 1688–1694 (2012).Pasta, M. et al. Full open-framework batteries for stationary energy storage. Nat. Commun. 5, 1–9 (2014).Firouzi, A. et al. Monovalent manganese based anodes and co-solvent electrolyte for stable low-cost high-rate sodium-ion batteries. Nat. Commun. 9, (2018).Pasta, M., Wessells, C. D., Cui, Y. & La Mantia, F. A desalination battery. Nano Lett. 12, 839–843 (2012).Lee, J., Kim, S. & Yoon, J. Rocking Chair Desalination Battery Based on Prussian Blue Electrodes. ACS Omega 2, 1653–1659 (2017).Kim, T., Gorski, C. A. & Logan, B. E. Low Energy Desalination Using Battery Electrode Deionization. Environ. Sci. Technol. Lett. 4, 444–449 (2017).Porada, S., Shrivastava, A., Bukowska, P., Biesheuvel, P. M. & Smith, K. C. Nickel Hexacyanoferrate Electrodes for Continuous Cation Intercalation Desalination of Brackish Water. Electrochim. Acta 255, 369–378 (2017).Jones, E., Qadir, M., van Vliet, M. T. H., Smakhtin, V. & Kang, S. mu. The state of desalination and brine production: A global outlook. Sci. Total Environ. 657, 1343–1356 (2019).Metzger, M. et al. Techno-economic analysis of capacitive and intercalative water deionization. Energy Environ. Sci. 13, 1544–1560 (2020).Sebti, E. et al. Removal of Na+ and Ca2+ with Prussian blue analogue electrodes for brackish water desalination. Desalination 487, (2020).Besli, M. M. et al. Performance and lifetime of intercalative water deionization cells for mono- and divalent ion removal. Desalination 517, 115218 (2021). Figure 1. (a) Battery-type water desalination approach in symmetric NiHCF/NiHCF cells with two salt water streams entering the cell and a brine stream and freshwater stream exiting the cell. (b) During galvanostatic charge/discharge cycling the salt concentrations of brine and freshwater stream can be monitored with microfluidic operando conductivity probes to determine important performance metrics. Figure 1

Renewable Energy Desalination for Island Communities: Status and Future Prospects in Greece

Energy and water are two of the most important components required to ensure prosperity and sustainable development to societies. This paper aims to review the status of renewable energy desalination for Greek islandic communities, deployed in two axes. The first one reviews the desalination systems state of the art technological solutions, their energy needs, how renewable energy may be employed and finally the cost of renewable energy desalination is investigated. The second axis focuses on Greek islands per se, where the current situation is investigated, potential solutions for meeting the water needs are evaluated, all leading to the proposal of a methodology towards designing an appropriate and applicable approach in addressing the water needs. Finally, a discussion takes place on how such options might be further deployed, particularly regarding the impacts they may produce for the livelihood and the future prosperity of the pertinent communities, and at the same time supporting the energy transition towards the EU Green Deal goals.

A solar energy desalination analysis tool, sedat, with data and models for selecting technologies and regions

There is interest for desalination technologies powered by solar energy as arid areas are typically bestowed with good solar potential. In response to a US DOE call for solar desalination analysis tools, we developed an open-source solar energy desalination analysis tool, sedat, for techno-economical evaluation of desalination technologies and selection of regions with the highest potential for using solar energy to power desalination plants. It is expected that this software will simplify the planning, design, and valuation of solar desalination systems in the U.S. and worldwide. Sedat uses Dash for integrating various layers of large volumes of GIS data with Python-based models of solar energy generation and desalination technologies. It derives time-series of energy generation and water production, with details of plant performance and suggestions for improving the solar-desalination coupling. This paper summarizes the various phases of the tool’s development, presents example results showing the potential, under multiple objectives, of solar desalination in parts of the U.S. southwest, and discusses method details that would be useful for future model development.

Knowledge and Technology Used in Capacitive Deionization of Water.

The demand for water and energy in today’s developing world is enormous and has become the key to the progress of societies. Many methods have been developed to desalinate water, but energy and environmental constraints have slowed or stopped the growth of many. Capacitive Deionization (CDI) is a very new method that uses porous carbon electrodes with significant potential for low energy desalination. This process is known as deionization by applying a very low voltage of 1.2 volts and removing charged ions and molecules. Using capacitive principles in this method, the absorption phenomenon is facilitated, which is known as capacitive deionization. In the capacitive deionization method, unlike other methods in which water is separated from salt, in this technology, salt, which is a smaller part of this compound, is separated from water and salt solution, which in turn causes less energy consumption. With the advancement of science and the introduction of new porous materials, the use of this method of deionization has increased greatly. Due to the limitations of other methods of desalination, this method has been very popular among researchers and the water desalination industry and needs more scientific research to become more commercial.

Fabric-based all-weather-available photo-electro-thermal steam generator with high evaporation rate and salt resistance

Solar-driven steam generation is a practical strategy to harness solar energy for desalination and production of clean water with a minimized carbon footprint. However, this strategy suffers from a low evaporation rate under weak illumination on cloudy days or at night. Herein, we present a fabric-based all-weather-available photo-electrothermal steam generator (P/ET-SG) capable of regulating the surface temperature and evaporation rate by the coupling effect of photo-thermal and electro-thermal heating depending on the light conditions. An unprecedented high surface temperature of 52°C in the wet state and an evaporation rate of 2.61 kg m−2 h−1 were achieved by the P/ET-SG under 1 sun with only 1 V input voltage owing to the uniform heat distribution and the coupled electro-thermal source. The oneway fluidic design of the P/ET-SG effectively prevented salt precipitation during continuous desalination in 24 h and was able to remove salt granules from the evaporation surface. Furthermore, the P/ET-SG demonstrated a high evaporation rate of 2.58 kg m−2 h−1 in the purification of concentrated saline water and dye-contaminated water with high efficiency (>99.9%). This study offers new thoughts for the design of all-weather-available solar steam generators with high efficiency and makes a step forward towards fast purification of concentrated saline water and wastewater.

Main Technical and Economic Guidelines to Implement Wind/Solar-Powered Reverse-Osmosis Desalination Systems

The use of renewable energy for desalination started in the 1980s, in order to provide a sustainable water supply in windy/sunny areas with water shortages. Nevertheless, this initiative has been generally limited to the R&D field and prototypes, with few units operating under real conditions. The research tradition in this field carried out by the Canary Islands Institute of Technology, based on pilot facilities, resulted in wide expertise on practical issues, as well as a deep knowledge on the state of the art. This paper deals with the most relevant technical aspects to be considered in the optimal design and operation of wind/photovoltaic (PV)-powered reverse-osmosis (RO) systems, focusing on practical indications: appropriate pre-treatment, the use and selection of the RO energy recovery system (ERD), the selection of an energy storage system, key recommendations for the O&M actions in wind- and PV-powered RO systems (extracted from the experience of operating different units in remote locations (PV and RO) and coastal areas (wind and RO)), and an identification of the pros and cons of hybrid systems. A selection of economic data is given, indicating the main aspects of the minimization of the cost of water. Finally, the paper mentions the latest advances in the involved technologies.

Integrated Water and Thermal Managements in Bioinspired Hierarchical MXene Aerogels for Highly Efficient Solar‐Powered Water Evaporation

AbstractSolar‐powered water evaporation is a straightforward, practical approach to use solar energy for water desalination. Solar absorbers made from photothermal materials capable of effectively confining heat and pumping water to the evaporation surface are essential for a high energy efficiency. However, separate designs of water transport routes and thermal insulating layers are required to simultaneously achieve desired water and thermal managements. This work reports an integrated design for efficient multifunctional capabilities through rational assembly of spectrally modified Ti3C2Tx (SM‐Ti3C2Tx) nanosheets and polyvinyl alcohol (PVA) into a multiscale 3D aerogel with a feather‐like microstructure. The aerogel contains longitudinal struts with transversely parallel ligaments developed at an angle of ≈60° from the struts, resembling the microstructure of down feathers in penguins and thus leading to excellent thermal insulation. The hydrophilic porous ligaments serve as upward water transport channels, pumping the water to the evaporation surface while confining it within the ligaments to avoid oversaturation. These functional features endow the composite aerogel with a high energy efficiency of 88.52% and an evaporation rate of 0.92 kg m−2 h−1 at a weak solar irradiance of 0.5‐sun, indicating its great potential for practical solar‐powered water desalination under natural sunlight.

Nature-inspired poly(N-phenylglycine)/wood solar evaporation system for high-efficiency desalination and water purification

The development of low-cost, scalable wood-based photothermal systems that utilize renewable solar energy for energy conservation and desalination has received extensive attention. Although some materials such as precious metals, semiconductor materials and carbon nanomaterials have been used as light absorbers, the issues of low evaporation rate and efficiency, as well as the high energy consumption and cost of photothermal layer design need to be addressed. In this work, inspired by the transpiration process of trees, a poly(N-phenylglycine) (PNPG)-wood solar evaporator was developed. The coating of PNPG, a conjugated polymer with good light absorption, greatly cover the shortage of weak light absorbance of wood, and effectively improved the solar-heat conversion efficiency. Moreover, benefited from the low thermal conductivity and special microstructure of the wood, the relationship among water transport, solar energy conversion, and heat regulation was better adjusted. As a result, the PNPG-wood system can effectively and quickly generate steam, the evaporation rate and efficiency can be 1.64 kg m–2 h–1 and 90.4% under 1 sun, which are higher than most reported wood-based solar evaporators. Hence, such a well-designed, cost-effective, durable, and high-efficiency solar evaporation system has the potential to be applied to solve the practical problem of seawater desalination and water purification.

A Comprehensive Investigation of Desalination Performance and Energy Consumption of Pulsed Electrodialysis

A Comprehensive Investigation of Desalination Performance and Energy Consumption of Pulsed Electrodialysis

The optimized flow-electrode capacitive deionization (FCDI) performance by ZIF-8 derived nanoporous carbon polyhedron

• Nanoporous carbon polyhedron (NCP) with high specific surface was prepared as flow-electrode. • A high salt removal rate of 20.98 μg cm −2 min −1 was obtained in FCDI system. • The increased NCP content can improve the desalination performance. • Desalination performance of NCP can keep stable even after long-time cycles. Flow-electrode capacitive deionization (FCDI) has developed as a promising technology to realize the highly efficient and low-energy-consumed desalination process. To deliver better desalination performance, the flow-electrode with high capacitance and low resistance is essential. As for the traditional AC flow-electrode, although it is low-cost and wide-applied, the relatively low capacitance and poor conductivity are the limitations for its further development. Here, we propose a novel flow-electrode material, nanoporous carbon polyhedron (NCP), which was prepared by ZIF-8 followed by carbonization and activation process and have a higher surface area and larger specific capacitance than AC. The desalination experiments showed that the current density of FCDI system based on NCP is about 2.5 times larger than that of AC, exhibiting a higher desalination rate of 20.98 μg cm −2 min −1 for NCP. Moreover, the desalination energy consumption and efficiency can keep relatively stable after the long-time continuous desalination cycling. This current research may be significant for the future promising application of high-performance FCDI system.

Experimental Study on the Influence of Flexible Control on Key Parameters in Reverse Osmosis Desalination

Variable-frequency drive (VFD) has been widely used in reverse osmosis desalination. Our purpose is to study how the VFD and pressure regulating valve affect the key parameters of reverse osmosis desalination and their action principle through experiments. Firstly, the power frequency is controlled by VFD, and the operating pressure is controlled by pressure regulating valve (needle valve) in the experiment. The feed water passes through the multimedia filter, precision filter and permeable membrane channel in turn, and permeate water and brine enter the fresh water tank and the brine tank respectively. Secondly, through experiments on seawater and brackish water respectively, the water flow rate, product water quality, energy consumption and recovery rate under different operating pressures are obtained when the power frequency is 25, 30, 35, 40, 45, and 50 respectively. Finally, combined with the working principle and mathematical model of VFD and high-pressure pump motor, the reason for the experimental results caused by the operation change is explained theoretically. The experimental results verify that for a certain recovery rate, the specific energy consumption required for water production decreases with decreasing power frequency. This provides desalination energy savings but at the expense of permeate production speed.

Power-to-gas utilization in optimal sizing of hybrid power, water, and hydrogen microgrids with energy and gas storage

Electricity and water have constituted two main requirements of human societies. Water desalination is considered as a prominent source of drinking water for the future needs. Supplying desalination energy and domestic electricity demand is mainly from the grid integrated with the fossil-fuel-powered plants. Additionally, the hydrogen demanded by the industry is currently produced from fossil fuels by reforming. This vast reliance on fossil fuels means high cost and pollution, and also energy security risks. Using renewable resources is a promising way to overcome these problems. However, a portion of the generated power is inevitably curtailed due to various reasons. The Power-to-gas (P2G) is a promising solution to mitigate renewable curtailment mitigation. Accordingly, this paper presents a combined configuration for supplying electricity, water, and hydrogen in a microgrid system integrated with the P2G concept. The microgrid relies on renewable power sources and is supported by the diesel generator and battery storage. The complete P2G cycle, including hydrogen production, storage, consumption, and converting back to electricity by a fuel cell, is modeled and optimized. The hydrogen production is made by the water electrolyze in addition to the gas reforming. Results of the simulations indicate the superiority of P2G utilization.

Integration of Wind Energy and Desalination Systems: A Review Study

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.

Stepped Solar Stills’ Development and Improvement for Seawater Desalination

Nowadays freshwater needs were covered by fossil fuel-based desalination systems in many areas over the world. However, fossil fuels’ excessive burning results in rapid depletion and pollution of the local environment as well as threat to life sustainability. Therefore, through the last few decades the scientific community focused on the systems relying on solar energy in seawater desalination as a clean alternative. Stepped solar stills, which convert solar energy to the required heat for producing freshwater in seawater desalination, are paid much attention. This article provides a comprehensive analysis of stepped solar stills’ development. Performance enhancement techniques, desalinated water production, efficiency and maximum theatrical production are discussed. This work aims to keep researchers and concerned scientific community abreast of stepped solar stills’ improvements. Such stills of low construction and running costs can meet the freshwater daily needs for small communities in coastal areas, islands and rural areas especially in Mideast. In conclusion, this review clarified that the stepped type solar stills still need multiple improvements to enhance their production efficiency and freshwater quantity. Further attention should be paid to the design of modified stills to attain better and efficient solar heat absorption as well as evaporation of seawater.