Solar Desalination Research Articles

Making Interfacial Solar Evaporation of Seawater Faster than Fresh Water.

Interfacial solar evaporation-based seawater desalination is regarded as one of the most promising strategies to alleviate freshwater scarcity. However, the solar evaporation rate of real seawater is significantly constricted by the ubiquitous salts present in seawater. In addition to the common issue of salt accumulation on the evaporation surface during solar evaporation, strong hydration between salt ions and water molecules leads to a lower evaporation rate for real seawater compared to pure water. Here a facile and general strategy is developed to reverse this occurrence, that is, making real seawater evaporation faster than pure water. By simply introducing specific mineral materials into the floating photothermal evaporator, ion exchange at air-water interfaces directly results in a decrease in seawater evaporation enthalpy, and consequently achieves much higher seawater evaporation rates compared to pure water. This process is spontaneously realized during seawater solar evaporation. Considering the current enormous clean water production from evaporation-based desalination plants, such an evaporation performance improvement can remarkably increase annual clean water production, benefiting millions of people worldwide.

Synergistic Impact of Magnets and Fins in Solar Desalination: Energetic, Exergetic, Economic, and Environmental Analysis

This study investigates the effectiveness of combining magnets with parabolic and truncated fins in enhancing the distillation process of solar stills. The integration of magnets accelerated evaporation rates, while the fins increased the heat absorption area, resulting in improved output, vis-à-vis traditional solar stills. A comparative assessment revealed that the parabolic fin solar still (PFS) with magnets outperformed the truncated fin solar still (TCFS), producing 20%, 15%, and 16% more distillate at three different depths (1, 2, and 3 cm). The superior performance of the PFS is attributed to the magnetism of the water and the fins’ more extensive surface area for heat absorption. Efficiency measurements at a water depth of 1 cm showed that the PFS achieved the maximum energy and exergy efficiencies at 30.49% and 8.85%, respectively, compared with TCFS’s 25.23% and 6.22%. Economically, the PFS setup proved more feasible, with a 20.9% lower cost per liter of distilled water than TCFS. Additionally, the environmental impact assessment indicated a significant reduction in CO2 emissions, potentially generating revenues of approximately USD 1242.32 through carbon credits. These results reflect a considerable margin to enhance the efficiency of solar desalination through well-planned adjustments, which bodes well for the future of optimized solar distillation systems from an economic and environmental perspective.

Highly Efficient Porous Glass Solar Water Evaporator

AbstractThe global water crisis, exacerbated by excessive use and pollution, has resulted in energy scarcity and threats. Solar desalination provides a sustainable fix, with researchers developing photothermal materials and designs to improve efficiency and sustainability. Glass materials, with their exceptional chemical stability, are suitable for extreme desalination in acidic and alkaline conditions. In this work, we have developed a porous glass evaporator (PGE) with exceptional water evaporation efficiency, achieved through a novel fabrication method that blends glass powders with soluble salts to create structure with continuous pores. The evaporator's microstructure comprises micrometer‐scale pores that form interconnected porous channels, facilitating efficient water transport and preventing salt deposition. Under one sun irradiation, the PGE exhibits superior solar evaporation performance in pure water, achieving a rate of 2.21 kg m−2 h−1, with an evaporation efficiency of 98%. In more complex media, such as seawater and methylene blue solution, the PGE also displays excellent evaporation capabilities, reaching rates of 2.08 and 2.47 kg m−2 h−1, respectively. Even after sustained alternation between acidic and alkaline treatments, the PGE retains an impressive evaporation rate of over 2.0 kg m−2 h−1, coupled with structural robustness, making it a promising candidate for practical applications in extreme environments.

Numerical Investigation of Pyramid Solar Stills with PCM‐Nanoparticles and Absorber Fins: Enhanced Thermal Performance for Sustainable Water Desalination

ABSTRACTIn arid regions facing challenges of limited access to potable water and electricity, solar desalination stands out as a promising solution for producing clean water from brackish sources. This research intends to examine and enhance an innovative and sustainable solar desalination system. A computational study is conducted on a pyramid solar still (PSS) combined with a phase‐change material incorporated with nanoparticles, with a variety of absorber fins. The study investigates three configurations: a traditional pyramid–shaped solar still, one with square absorber fins, and another with circular fins. Paraffin wax mixed with Al2O3 nanoparticles is used beneath the absorber fins. Conservation equations are solved using COMSOL Multiphysics. Simulation outcomes demonstrate that the incorporation of finned absorbers, coupled with elevated water temperatures, significantly enhances the yield of the improved PSS compared with its conventional counterpart. The square‐finned absorber PSS exhibits a substantial increase in total accumulated productivity over the conventional design. Moreover, the PSS with square‐finned absorbers demonstrates an impressive average peak daily thermal efficiency improvement of 49.19% compared with a conventional solar still. This study highlights the effectiveness of the modified PSS as a superior option for household water generation.

Multi-objective optimization and exergoeconomic analysis of a novel solar desalination system with absorption cooling

This paper presents a novel design for a solar-powered desalination system utilizing a single-effect absorption refrigeration cycle with a flat-plate solar collector. The NH3-H2O working fluid pair in the refrigeration subsystem produces chilled water while the rejected heat from the condenser drives a humidification-dehumidification (HDH) subsystem for freshwater generation. This cycle has been analyzed thermodynamically and exergetically to understand its key performance parameters. Furthermore, for a detailed examination and optimization, an exergoeconomic analysis was also conducted. Design parameters for this study include the tilt angle of the solar collector, Volume fraction of nanoparticles in the CuO nanofluid, Solar collector area, Base fluid mass flow rate in the collector, Mass flow rate of the strong solution, Absorber and condenser temperatures, Mass ratio and Humidifier effectiveness. The Objective functions used to evaluate the system, performance are the Cooling effect of performance (COP), Energy performance (EP), Exergy efficiency (μExe), and the Total product cost rate of the system (Ċp,Tot). The genetic algorithm optimization is employed to find the best system performance using two sets of three objective functions. The effectiveness of multi-objective optimization using LINMAP, TOPSIS, and Shannon Entropy methods is demonstrated. LINMAP and TOPSIS consistently achieved improvements in COP (32–42 %), exergy efficiency (33–48 %), and reduced total cost (89–90 %) compared to the base point, while Shannon Entropy offered slightly lower gains. These methods consistently identify superior system configurations, achieving significant improvements in performance while minimizing the total product cost rate.

Advances in solar desalination using 2D and biomass derived materials: A roadmap to sustainability

Advances in solar desalination using 2D and biomass derived materials: A roadmap to sustainability

High salt-resistant and robust MXene@oleylamine/PET composite nonwoven for efficient and long-term solar desalination

2D transition metal carbides/nitrides/carbonitrides (MXenes) have received extensive attention in solar seawater desalination due to their hydrophilicity, 100 % photothermal conversion efficiency, and efficient light-trapping by enhancing localized surface plasmon resonance (LSPR). Nevertheless, the easily oxidizable characteristics of MXenes, along with salt accumulation and structural weakness impede their practical application in solar-driven interfacial evaporators. Herein, a hydrophobic MXene@oleylamine/polyethylene terephthalate (MXene@OAm/PET) nonwoven with long-term operational stability is fabricated via firmly chemical cross-linking between oleylamine (OAm) modified MXene (MXene@OAm) and NH2-PEG-COOH treated PET nonwoven (PEG-PET). The MXene@OAm endows excellent oxidation resistance and hydrophobicity. The prepared MXene@OAm/PET nonwoven which exhibits broad-spectrum solar absorption and high efficiency, can achieve an average evaporation rate in 3.5 wt% NaCl solution at 1.26 kg·m−2·h−1 and no seeable salt deposition during 15 irradiation cycles for 8 h a day indicates its superior salt resistance and long-term stability. Most importantly, after being soaked in 3.5 wt% NaCl solution for 40 days, the evaporation rate of MXene@OAm/PET nonwoven still remains stable at around 1.22 kg·m−2·h−1, indicating the significant potential of this prepared nonwoven for long-term seawater desalination and its suitability for industrial applications. Even in industrial wastewater, the evaporation rate can reach 1.27 kg·m−2·h−1. This work demonstrates a successful strategy for achieving high efficiency, stability, and superior salt resistance, which can be potentially utilized in seawater desalination and wastewater treatment.

Superhydrophobic pancake-like graphene oxide for zero liquid discharge solar desalination of real brines

Solar interfacial desalination offers a promising solution to meet the demand for portable water, especially in arid regions. Although various materials have demonstrated high solar-to-steam conversion efficiencies in concentrated solutions, most studies have utilized simulated solutions rather than real seawater. Herein, we developed a pancake-like graphene oxide photothermal membrane with superhydrophobic properties optimized for interfacial heating to desalinate real seawater and brine. Under 1 sun, the membrane efficiently achieves a sustained high evaporation rate of 1.23 kg.m−2.h−1 with a photothermal conversion efficiency of 80 %, while remarkably facilitating salt harvesting. Notably, the membrane maintained stable performance and exhibited no salt accumulation on its surface when tested outdoors with real seawater, demonstrating its practical scalability. The membrane exhibited long-term stability in desalination processes, with full performance restoration through an energy-free cleaning method. These results highlight a potential pathway toward zero-liquid discharge desalination.

Towards cleaner desalination systems utilizing waste heat: a bibliometric analysis

Water scarcity is a global issue facing the coming generations. Desalination is a dependable, nonconventional freshwater method. However, desalination is an energy-intensive water treatment method. The primary energy source used to power various desalination processes for thermal and electrical energy consumption is fossil fuels, such as coal, oil, and gas. The widespread use of fossil fuels has been linked to climate change and global warming, leading to numerous demands to reduce their usage and energy utilization. Waste heat has an excellent potential for energy recovery that can reduce the consumption of fossil fuels. This research study has been conducted to evaluate related waste heat desalination literature with data analysis, bibliometric, and clustering methods. Based on articles published between 2013 and 2023, the current study analyzed existing trends, distribution of publication subjects, journals' performances, countries' collaborations, affiliations' performances, most cited publications, authors' contributions, keyword analysis, and future perspectives on waste heat desalination systems. The findings showed that the most active journal in this field is Desalination, with 133 publications and 6332 citations. China led in publications with 242, while the United States topped the list of citations with 3598. Also, King Abdullah University of Science and Technology in Saudi Arabia published 50 documents. The top 10 institutions in this field of research are in the Middle East and North Africa (MENA) region and Asia, particularly in Saudi Arabia, China, Iran, Egypt, and Singapore. Moreover, the most frequently used terms are analyzed and clustered into three main topics. The top 3 clusters are solar-powered desalination technologies, membrane-powered desalination technologies, and power cycles driving desalination technologies.

Cost-Effective multifunctional bilayer structural hydrogel evaporator for stable solar desalination and wastewater treatment

Cost-Effective multifunctional bilayer structural hydrogel evaporator for stable solar desalination and wastewater treatment

Design, construction and performance analysis of a four-fold pyramid shaped solar still with different insulation materials and activated carbon

A four-fold pyramid-shaped solar desalination system has been constructed to produce fresh water for the coastal residents in Bangladesh. To evaluate the heat-storage effectiveness of activated carbon from sugarcane bagasse which was synthesized by KOH activation method and confirmed through SEM/EDS analysis was assessed in a prototype desalination setup. Among the four different insulating materials in the drawer-style chamber of solar still, the PE (polyethylene) foam combined with aluminum foil showed the most effective material for heat retention since it has a low emissivity with a minimum conductive heat transfer loss of 1.65 ± 0.44 W. With a solar radiation of 13.73 MJm−2day−1, the system produced 1.35 kgm−2 of water on November 22, 2023, in Bangladesh. After analyzing the freshwater properties, the salinity, pH, TDS, SG, ORP, and EC of fresh water have been found 0 %, 6.95, 50 ppm, 1.003, −36mV, and 26 μScm−1 respectively. Moreover, the device has an efficiency of 22.64 % with a payback period of 3.3 years. The average distillation value of developed solar still has been found 65 % greater when activated carbon is present. The study also highlights technical optimization and economic feasibility and this solar desalination system presents a promising solution to alleviate freshwater scarcity in Bangladesh.

Bidirectional solar water production enabled by a breathable Janus photothermal material

Solar-driven interfacial water evaporation offers a promising solution to the global scarcity of freshwater. Despite advances in increasing evaporation rates, current condensate productivity is limited to 0.3 − 0.5 kg m−2 h−1 due to unidirectional vapor diffusion, which is insufficient to satisfy water demands. This paper introduces a bidirectional solar water production (BSWP) device that utilizes a breathable Janus photothermal material made from recycled cotton fabric. The BSWP device allows vapor to diffuse in both upward and downward directions of the evaporation interface. This design features dual condensers, addressing the limitations of traditional solar stills by reducing vapor concentration and minimizing light loss due to condensation on the top cover receiving light. Under 1 sun illumination, the BSWP device achieves a water yield of 1.06 kg m−2 h−1 with a solar-to-water efficiency of 71%. An 10-hour outdoor experiment demonstrates that the BSWP device can yield a water flux of 9.65 kg m−2, showcasing its potential for efficient water generation in practical environmental conditions. The present work provides a new perspective on the structural design of direct solar desalination configurations, potentially offering a more effective solution to cope with global water scarcity.

A typha orientalis-inspired 3D Janus solar evaporator with controllable wettability for highly efficient and stable solar desalination

A typha orientalis-inspired 3D Janus solar evaporator with controllable wettability for highly efficient and stable solar desalination

Organic Phase Change Materials as Thermal Energy Storage for Automated Solar Seawater Desalination System

A prototype of an automated solar seawater desalination system equipped with thermal energy storage was designed and developed to analyze experimentally the effect of adding organic phase change materials (palm wax and beeswax) to the desalination system’s efficiency. The desalination machine was set up with two configurations: with organic and without organic PCMs. While the setup without a PCM can produce an average of 30.8 mL per day and convert 2.056% of the total volume of input water to an output peak of 48.5 mL using solar energy, the setup with a PCM can produce an average daily water production of 68.9 mL and convert 4.6% of the input water volume with the highest record output of 104.5 mL compared to configurations without PCM, the organic PCM system with a 1:1.2 mixture of beeswax and palm wax can produce an average of 123.7%.

Innovative solar-assisted direct contact membrane distillation system: Dynamic modeling and performance analysis

The study presents an innovative solar-assisted dual-tank direct contact membrane distillation (DCMD) system designed to enhance the operational stability and efficiency of solar-powered desalination. The proposed system integrates a dual thermal storage tank configuration, allowing for continuous operation by alternating between two tanks that store pre-heated water, thereby mitigating the impact of solar energy fluctuations. The dynamic modeling approach used in this study predicts the system's performance under varying solar conditions, focusing on key parameters such as permeate flux, evaporation efficiency, and specific thermal energy consumption. The simulation results show that the system achieves an average permeate flux of 14.4 L/h m² and a thermal efficiency of 53.3 % at a hot water temperature of 60 °C, with a corresponding average specific thermal energy consumption of 1567 kWh/m³. These findings highlight a substantial improvement in both thermal efficiency and water production compared to conventional single-tank systems.The dual-tank DCMD system is particularly suited for deployment in remote or arid regions where stable and efficient freshwater production is critical. This research provides a comprehensive analysis of a novel solar-assisted desalination technology, contributing to the advancement of sustainable water resources management by providing a reliable and scalable solution that can maintain high operational efficiency even in remote areas with variable solar conditions.

Comparative thermal model analysis and experimental validation for predicting performance of a pyramidal solar still with integrated pulsating heat pipe

Developing nations face a dire situation as water scarcity and pollution significantly impact various aspects of life. It's crucial to take action now to address these pressing issues and ensure a sustainable future for all. Solar desalination processes emerge as a promising solution to these pressing problems in water purification technologies.This paper reports the thermal modeling and experimental results of two solar still designs, namely (i) Pyramidal solar still with pulsating heat pipe (PHP), Modified pyramidal solar still (MPSS), and (ii) conventional pyramidal solar still (CPSS). This study uses energy balance equations to focus on MPSS and CPSS thermal modeling. In the MPSS, a PHP, in conjunction with a solar collector, provides external heat to basin water. Several models, including Dunkel, Kumar and Tiwari, Chen, and Zheng Hongfei, are utilized to estimate the performance of both MPSS and CPSS. Extensive experiments have been conducted for validation purposes. Key parameters considered for prediction and comparison include evaporative heat transfer coefficient, convective heat transfer coefficient, total heat transfer coefficient, and hourly yield. It is noted that the Kumar and Tiwari model demonstrates a superior ability to predict cumulative yield, with a percentage error of 5.81 % and 5.9 % for MPSS and CPSS, respectively, compared to the experimental cumulative yield. The theoretical average basin water temperature observed in MPSS is 64.56 °C, and CPSS is 58.8 °C. The enhancement in temperature is attributed to the supplementary heat provided by the PHP.

In Situ Growth of Well-Aligned MOF Nanoneedle Arrays into Composite Photothermal Membranes for Solar Desalination.

The solar-driven interfacial evaporation (SDIE) technology serves as a clean and facile approach combining seawater desalination to address water shortage and energy crisis. Recently, porous organic framework materials have aroused great attention, and the development of MOF-based composites with significant performance in photothermal conversion and water activation has become one of the important focuses in this field. In this work, an MOF-based composite photothermal membrane (PON@MOF) was prepared via the in situ growth of metal-organic framework (MOF) nanoneedle arrays induced by a pyridine-based organic polymer nanowire network (PON). The PON@MOF membrane possessed an MOF array layer, a PON-induced layer, and a porous support layer. The PON is rich in coordinated nitrogen atoms for anchoring the metal-ion source, and the main role of the PON layer is to provide favorable nucleation sites and orient in situ growth of well-aligned MOF nanoneedle arrays. With the highly conjugated framework of PON@MOF and the light trapping of the nanoarrays strengthening the photothermal conversion as well as the hydrophilic chemical structure facilitating the decrease of the water evaporation enthalpy, the PON@MOF membrane realizes highly efficient thermal vapor conversion. Under solar irradiation (1.0 kW m-2), PON@MOF demonstrated an evaporation rate of 2.14 kg m-2 h-1 and a solar-to-vapor conversion efficiency of 98.5%. Meanwhile, the PON@MOF membrane has excellent salt resistance and stability, highlighting its potential application in desalination. Overall, this work provides a special idea for the structural design of photothermal composites for solar desalination and freshwater production.

An experimental exploration of modified basin solar still performance through integration of flat plate collector and built condenser

AbstractThis study experimentally investigates the integration of a flat plate solar collector and a condensation chamber into a basin solar still. Three prototypes were designed and constructed for evaluation: a basin solar still coupled to both a solar collector and a condensation chamber, a basin coupled with a solar collector, and a simple basin solar still as a reference. The experiments, conducted from July 24 to 28, 2016, at the UDES site in Bouismail, Algeria, used seawater from the Fouka region. Solar radiation emerged as the primary influencer on the solar desalination system, with active solar stills, particularly those equipped with a flat plate collector, showing significant temperature increases. Daily cumulative production analysis revealed the condensation chamber as a significant contributor, representing 58% of total production. Incorporating a flat plate collector resulted in a 110% increase in daily production compared to the conventional solar still. Simultaneously incorporating both the flat plate collector and the condensation chamber showcased an impressive 176% increase in daily production. Daily production quantified at 5.9 kg/m2 for the active with a condensation chamber, 4.5 kg/m2 for the active solar still, and 2.1 kg/m2 for the simple solar still. Economic analysis indicated that the active solar still with the condensation chamber enables more cost‐effective freshwater production than the active solar still alone. Water analyses demonstrated the efficiency of solar distillation, converting high‐salinity saltwater (31.4%) into exceptionally pure distillate (0.00%).

Productivity forecasting of the solar still with phase change material using LSTM and GRU neural networks

Abstract Solar desalination is one of the renewable energy techniques by which freshwater can be obtained economically. Solar desalination experiments are time and resource-consuming methods; there is a need for a robust system to identify the serviceability of the solar still in a specific region. The objective of this study is to develop a forecasting model using artificial neural networks to predict freshwater productivity. The study specifically aims to compare the accuracy of Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) neural networks in forecasting the productivity of Conventional Solar Stills (CSS) and Solar Stills with Phase Change Material (SSPCM). The current investigation involved analysing the experimental outcomes of a solar still that employed phase change material (PCM) and pin fins. Palmitic acid was implemented as the energy storage material and was placed beneath the absorber plate. The neural network model was trained and validated using time-series solar still experimental data. Different statistical measures were utilised to evaluate the accuracy of Long Short Term Memory (LSTM) and Gated Recurrent Unit (GRU). The results indicate that the freshwater productivity forecasted by LSTM exhibited greater accuracy than GRU. Specifically, the coefficient of determination values for LSTM were 0.96 and 0.98 for the CSS and SSPCM, respectively, which were better than the corresponding values for GRU.

Ultra‐Durable Solar‐Driven Seawater Electrolysis for Sustainable Hydrogen Production

AbstractIons in seawater hinder direct sewage electrolysis due to the extreme corrosion of Cl− to the anode and reaction of Mg2+ and Ca2+ on the cathode producing solid substances, which reduce the electrolytic efficiency. However, traditional desalination consuming fossil fuel with massive CO2 emissions threatens human survival. Therefore, zero‐carbon emission, ultra‐durable, large‐scale production of freshwater from seawater for water electrolysis is urgently needed. Herein, a multifunctional system for seawater is demonstrated electrolysis based on ultra‐durable solar desalination outdoors. The solar evaporators reach an evaporation flux of 1.88 kg m−2 h−1 with a photothermal conversion efficiency of solar energy as high as 91.3% with excellent ultra‐durable salt resistance even for saturated saltwater due to the Marangoni effects. Moreover, the condensation of pure water from solar desalination based on the evaporation system reaches 0.54 L m−2 h−1 outdoors, which is suitable for a 20 cm × 20 cm engineered electrode equipped with a Janus membrane powered by a solar panel to produce H2 outdoors. The ultrafast unidirectional transport of H2 bubbles enabled by Janus membranes can greatly improve the H2 production efficiency at a rate approaching 85 mL h−1 for continuous 24 h outdoors.