Solar Desalination Research Articles

A MoS2-based evaporator with porous structure and interlayer channels for solar desalination and photocatalytic degradation

The solar interfacial evaporator is a highly promising method for producing fresh water and has garnered significant attention due to its environmental friendliness and low energy consumption. MoS2, a frequently used semiconductor material for interfacial evaporation, has been the focus of research aimed at enhancing evaporation rate and efficiency, with less consideration given to its salt resistance and other potential capabilities. In this work, we introduce a novel ANF/MoS2@MXene evaporator that employs vertically aligned MoS2 nanosheets coated on MXene as the photothermal material and aramid nanofiber aerogel (ANF) as the substrate. The evaporator exhibits both photothermal and photocatalytic degradation effects. The existence of MXene and vertically oriented MoS2 nanosheets contributes to a broad light absorption spectrum, resulting in an evaporation rate of 1.42 kg m-2h−1 and an efficiency of 95.84 % under one sun. Additionally, the porous structure and interlayer channels within the ANF facilitate rapid water transfer and timely salt discharge. This leads to a stable evaporation rate of 1.28–1.37 kg m-2h−1, preventing salt crystal accumulation on the evaporator’s surface during 10 h of continuous operation in 3.5 % NaCl solution. The evaporator also demonstrated an effective degradation rate of 89.24 % in treating dye wastewater after 2-hour light exposure. This work presents a promising approach for constructing a photothermal evaporation/photocatalytic bifunctional system with enhanced salt resistance for MoS2-based evaporators.

Experimental investigation of a novel hybrid solar-geothermal desalination process

The widespread application of renewable energy, particularly in water desalination, is critical for addressing global water scarcity. This paper proposes a novel hybrid sustainable desalination method that harnesses both solar and shallow geothermal energy through evaporation and condensation processes. The desalination device under consideration uses a parabolic trough solar collector to evaporate saline water, and then transports the generated water vapor to an underground vertical conduit. The vapor cools as a result of the underground low temperature, leading to condensation and the formation of fresh water. To assess the freshwater production capacity of the proposed system, a simple lab-scale prototype was developed. The experimental prototype's findings emphasize the substantial influence of temperature and velocity of water vapor at the inlet of the buried pipe on the efficiency of freshwater production. Despite its small scale, the prototype outperforms other solar desalination methods, producing a remarkable output of 740 ml/h of fresh water under specific conditions (temperature: 53 °C, velocity: 1.4 m/s) With an estimated productivity of 90 l m−2 day−1,the present desalination prototype is more effective when compared with other earlier experimental studies of solar desalination systems such as active solar still and humidifier, dehumidifier solar systems, This research contributes to the advancement of sustainable desalination technologies, holding promise for addressing water scarcity challenges globally.

Evaluation of suitable sites for concentrated solar power desalination systems: case study of Mauritania

It is imperative to address the critical problem of water scarcity in sub-Saharan Africa, especially in light of the aggravating effects of climate change brought on by the extraction of fossil fuels. In order to ensure the availability of drinkable water in these places, this research proposes integrating concentrated solar power (CSP) with desalination systems (DS). Present research is focused on identifying and evaluating potential locations for DS/CSP implementation within Mauritania by employing a comprehensive, multi-criteria decision-making framework. This framework synthesizes mathematical approaches from multi-criteria analysis with geospatial analysis techniques, considering a range of factors including environmental impact, economic viability, demographic demands, and climatic conditions. Research findings reveal that 10% of the Mauritanian, approximately 103070 km2, presents optimal conditions for the deployment of DS/CSP facilities. The study delineates the coastal regions as prime candidates for seawater desalination plants, while the densely populated southeastern areas are identified as suitable for brackish water desalination systems. Conversely, the less inhabited northern territories hold the potential for decentralized brackish water desalination plants. Hence this study provides a holistic approach for DS/CSP systems installation to manage water scarcity as well as energy security issues in Mauritania. And also provides basis for formulating future policies in the region.

Enhanced hydrophilicity and stability of carbon-based aerogel with assembling of halloysite nanotubes and silica fibers for efficient solar seawater evaporation and desalination

Solar vapor generation has emerged as a sustainable technique for seawater evaporation and desalination. Integrating high hydrophilicity, strong light absorbance, good salt resistance, fast water transfer and good structural stability simultaneously in one evaporator at low cost for achieving cost-effective evaporation and long-term utilization is highly desirable but still challenging. Herein, an eco-friendly and low-cost aerogel (CSH) with natural chitosan, halloysite nanotubes and silica fibers was prepared by freeze-casting, which was then carbonized to construct a robust aerogel (cCSH) as evaporator. The cellular structure of cCSH aerogel with microchannels enables fast water transfer and rapid salt dissolution, the carbonized chitosan favors enhanced light absorption, the halloysite assembled on the walls endows the aerogel with excellent hydrophilicity, and the silica fibers penetrating the multilayer guarantee good structural stability. As expected, the prepared evaporator (cCSH200) exhibits remarkable evaporation rates of 2.49/7.20 kg·m−2·h−1 under one/four sun, respectively, exceeding most biomacromolecule-derived aerogels. Besides, it displays outstanding salt resistance, wastewater purification ability and long-term cycle stability. Outdoor test further substantiates the admirable evaporation performance, long-term durability and enormous application prospect of the cCSH200. This work affords a low-cost tactic for the development of efficient evaporator for solar-driven seawater desalination and wastewater treatment.

CuS and polydopamine-modified polyvinyl alcohol foam for steady interfacial solar desalination of high saltwater

Interfacial solar desalination generation (ISDG) presents a promising solution for obtaining freshwater from seawater. However, developing solar evaporators with robust salt resistance using simple methods to ensure consistent desalination performance remains a major challenge. In this study, we engineered a solar evaporator (CuS-PDA-PVAF) by modifying polyvinyl alcohol foam (PVAF) with polydopamine (PDA) and CuS using a straightforward solution immersion method. The incorporation of PDA and CuS enhances the sunlight absorption capability of PVAF to approximately 98 %, resulting in an evaporation rate of 1.44 kg m–2 h–1 under 1-solar intensity. The CuS-PDA-PVAF solar evaporator leverages the macroporous structure and excellent hydrophilicity, enabling it to withstand 15 wt% saltwater while maintaining a steady evaporation rate of about 1.17 kg m–2 h–1. Outdoor tests confirm that a 1 m2 CuS-PDA-PVAF can generate approximately 5.6 kg of freshwater daily. This solar evaporator, designed simply and resistant to salt, possesses substantial potential for alleviating freshwater scarcity.

Solar-Powered Desalination as a Sustainable Long-Term Solution for the Water Scarcity Problem: Case Studies in Portugal

Solar-Powered Desalination as a Sustainable Long-Term Solution for the Water Scarcity Problem: Case Studies in Portugal

Plasmon-Enhanced Light Absorption Below the Bandgap of Semiconducting SnS2 Microcubes for Highly Efficient Solar Water Evaporation.

Semiconducting materials show high potential for solar energy harvesting due to their suitable bandgaps, which allow the efficient utilization of light energy larger than their bandgaps. However, the photon energy smaller than their bandgap is almost unused, which significantly limits their efficient applications. Herein, plasmonic Pd/SnS2 microcubes with abundant Pd nanoparticles attached to the SnS2 nanosheets are fabricated by an in situ photoreduction method. The as-prepared Pd/SnS2 microcubes extend the light-harvesting ability of SnS2 beyond its cutoff wavelength, which is attributed to the localized surface plasmon resonance (LSPR) effect of the Pd nanoparticles and the 3D structure of the SnS2 microcubes. Pd nanoparticles can also enhance the light absorption of TiO2 nanoparticles and NiPS3 nanosheets beyond their cutoff wavelengths, revealing the universality for promoting absorption above the cutoff wavelength of the semiconductors. When the plasmonic Pd/SnS2 microcubes are integrated into a hydrophilic sponge acting as the solar evaporator, a solar-to-vapor efficiency of up to 89.2% can be achieved under one sun. The high solar-to-vapor conversion efficiency and the broad applicability of extending the light absorption far beyond the cutoff wavelength of the semiconductor comprise the potential of innovative plasmonic nanoparticle/semiconductor composites for solar desalination.

Carbon black and polyetherimide modified ES nonwovens for low-cost and continuous seawater desalination

Solar-powered desalination is considered a promising and sustainable method for producing clean water to alleviate freshwater shortages. However, most solar evaporators have drawbacks such as high costs, complicated processes and lack of durability. Here, we present solar evaporators modified with polyethyleneimine and gallic acid, decorated with carbon black nonwovens, for desalination to produce clean water. The carbon black photothermal nonwovens were produced by treating ES hot air nonwovens with a spray of carbon black solution. Utilizing the light-absorbing heat generation of carbon black and the skin-core structural characteristics of ES(PE/PET) nonwoven, the carbon black is firmly embedded in the PE skin layer of the nonwoven fabric. Subsequently, mussel chemistry inspired the formation of polyethyleneimine and gallic acid coatings on the surface of the carbon black-loaded nonwoven. By combining carbon black with mussel coatings, the photothermal nonwovens demonstrated improved hydrophilicity, excellent photothermal water evaporation performance, and enhanced light conversion efficiency. The modified interfacial evaporator exhibited a high evaporation rate of 1.22 kg m−2·h−1 and had high cost-effectiveness of 332.4 g·h−1·$−1. In addition, reusing, desalination, and outdoor experiments were conducted to showcase the potential of the evaporator for practical desalination. This work demonstrates the significant potential of photothermal ES nonwovens for efficient solar-driven clean water production to tackle global freshwater shortages.

Enhanced performance of a hybrid adsorption desalination system integrated with solar PV/T collectors: Experimental investigation and machine learning modeling coupled with manta ray foraging algorithm

This study explores the performance augmentation of a solar adsorption desalination system (SADS) powered by a hybrid solar thermal system with evacuated tubes and photovoltaic thermal (PV/T) collectors, both numerically and experimentally. The system concurrently generates both electrical power via the PV/T system and desalinated water through the SADS. The cooling of photovoltaic cells is achieved through the utilization of chilled water produced during the desalination process of the SADS, which aims to enhance the electrical efficiency of photovoltaic cells and optimize the overall utilization of the adsorption distillation cycle. The SADS is examined under different operational scenarios and thoroughly assessed in terms of specific cooling power, specific daily freshwater product, and the coefficient of performance (COP). More so, a hybrid machine learning framework integrating an adaptive network-based fuzzy inference system (ANFIS) fine-tuned through the utilization of a manta ray foraging optimization algorithm (MRFOA) is also developed to predict the performance parameters of the SADS. The experiments indicated that the modified PV/T system improved the PV efficiency by 18 % at peak time, where the yielded electrical power and electrical efficiency reached 112 W/m2 and 11.13 %, respectively. The specific freshwater product (SWP), specific cooling power (SCP), and COP of the SADS are estimated as 53.3 L/ton-cycle (6.30 m3/ton-day), 153 W/kg, and 0.25, respectively. Furthermore, Furthermore, the simulated findings showed that the deterministic coefficient and RMSE of the predictive SWP are 0.989 and 1.314 for ANFIS-MRFOA and 0.965 and 2.323 for typical ANFIS, respectively. Hence, the ANFIS-MRFOA exhibited the highest prediction accuracy and can be deemed a potent optimization tool for forecasting the energetic performance of adsorption distillation systems.

High-Efficiency Photothermal Water Evaporation under Low-Intensity Sunlight Using Wood Biochar Monolith.

Utilizing energy directly from the sun, solar water evaporation drives the global hydrological cycle and produces freshwater from saline water in the oceans and on land. As water is a poor solar absorber, a photothermal material is needed to facilitate the conversion of photons to thermal energy and increase the efficiency of solar desalination. However, the current photothermal materials are less efficient and expensive to be manufactured. Inspired by nature, we created a new photothermal material called a wood biochar monolith (WBM) by carbonizing wood using the pyrolysis process at 1000 °C and subsequently steaming at high pressure. Under low light intensity (193 W/m2), the light to vapor efficiency of maple WBM is more than 100%. The outstanding performance of WBM is attributed to (1) the facilitated water transport in the hierarchical, open-pore network preserved from the wood precursor in WBM and (2) the reduced evaporation enthalpy of confined water in WBM and the high broadband sunlight absorptivity of WBM. Moreover, the high evaporation rate causes the temperature of WBM to be lower than that of the surrounding water, enabling thermal energy harvesting by WBM from water and making a light-to-vapor efficiency of >100% feasible. This discovery offers opportunities for developing low-cost, high-performance water desalination or humidification devices deployable in remote areas with nonconcentrated natural sunlight.

Augmenting hemispherical solar still performance: A multifaceted approach with reflectors, external condenser, advanced wick materials, and nano-PCM integration

This study aims at improving the desalination process of hemispherical solar still (HSS). A modified HSS (MHSS) design was developed, incorporating a 35 cm radius hemispherical absorber to heighten vaporization area and sun exposure. The influence of various factors on the MHSS performance was evaluated: wick material (jute cloth vs. cotton wick), rear reflectors for concentrated solar radiation, fan integration for enhanced heat transfer, and a phase change material (PCM) with silver nanoparticles (Ag) positioned beneath the liner. The MHSS design itself achieved a 96 % gain in productivity over HSS. Jute cloth proved to be a more effective wick material than cotton. The MHSS equipped with external reflectors exhibited a significant 120 % improvement in productivity. Furthermore, fan integration within the MHSS resulted in a 172 % productivity increase (11150 mL/m2⋅day compared to 4100 mL/m2⋅day for the HSS). Besides, the enhancement (152 %) was observed with the MHSS incorporating both a fan and a PCM-Ag composite, yielding a total daily freshwater production of 10500 mL compared to 4150 mL for the HSS. These findings suggest that the MHSS design with optimized features, particularly the use of a fan and PCM-Ag composite, offers a promising approach to significantly improve solar desalination performance.

A data-driven method to construct prediction model of solar stills

The interdisciplinary field between solar desalination and machine learning is the subject of a cutting-edge study. Generally, the studies treat data acquisition and model construction as independent processes, leading to problems such as insufficient dataset size or resource wastage. This study proposes a data-driven method that integrates data acquisition with model construction processes. By using the Bayesian optimization algorithm, the method accelerates the convergence of model accuracy. By comparing the results of 100 pairs of simulations, it is found that the models using the data-driven method are more accurate than traditional expert-driven methods in 70 % of compared results. Additionally, when it makes a model with the mean absolute percentage error as 5 %, the proposed data-driven method requires 220 additional data on average, compared to 258 with the traditional expert-driven method, representing a 14.7 % reduction. This work offers new ways and a broad application of the interdiscipline between solar desalination and machine learning.

Modelling and Analysis of a Single Slope Solar Still for Desalination of Water

Nowadays, brackish water/seawater desalination is a subject of concern to many researchers all over the world. Solar desalination is a renewable energy-driven method that produces freshwater from saline/brackish water. Many coastal countries suffer from a scarcity of freshwater. Solar-driven desalination is an optimistic and sustainable method to reduce the shortage of potable water in remote regions. Solar desalination is a viable way to produce potable water from any type of non-drinkable water. The recourse to use of solar energy in desalination by distillation, represents as appreciable part of water resources and is realizable, simple, cost-effective, operational solution technically. In this work, Modelling and simulation analysis of single-slope solar still for desalination of water is investigated in CFD-Ansys by considering solar radiation data at 12.8852°N, 77.572625°E in Bengaluru, Karnataka, India. The simulation results found that, the solar still yields the distillate at the rate is 2 litres/m2 for 10 litres of saline water that runs for 12 hours a day (from 7:00 am to 6:00 pm). A comparison between various inclination angles were performed. Solar still yields thermal efficiency of 24% at the inclination angle of 38° when compared with the inclination angles of 22°, 28°, 32° and 44°.

EVALUATION OF ENHANCED SOLAR DESALINATION SYSTEM PROTOTYPE

Solar desalination technology has been one of the effective solutions to tackle the problem of water scarcity. A number of studies have been conducted at our water research group to determine which variable influences the quantity of distilled water produced by an independent solar desalination unit. Aims: This study was aimed to design and optimize a novel solar desalination unit and field-tested using the best variable from the previous studies. Methodology and results: Variables used from the previous studies were evaluated to obtain the best values for each parameter, those are: glass cover inclination, gap distance between water and glass cover, insulation thickness, water depth, and water mass flow rate. Those best values were then implemented in the optimized basin design, delivery mechanisms, evaporation techniques, and heat isolation methods. The optimized design can generate up to 2,778.2 mL/m2/8hrs of distilled water with an efficiency of 23.35% in preliminary test, and was field tested at Batukaras Beach, where it produced up to 902 mL/m2/8hrs with an efficiency of 13.56%. Conclusion, significance and impact study: Meteorological parameters and environmental conditions are important factors that greatly affect the performance and productivity of the desalination unit. The relative humidity is inversely proportional to the volume of distillate water, where the smaller the value, the greater the amount of distillate water that can be produced, and it has significant impact on the productivity of the prototype. The quality of the distillate water produced still needs improvement on the parameters of pH, turbidity, and total coliform.

MXene: A Roadmap to Sustainable Energy Management, Synthesis Routes, Stabilization, and Economic Assessment.

MXenes with their wide range of tunability and good surface chemistry provide unique and distinctive characteristics offering potential employment in various aspects of energy management applications. These high-performance materials have attracted considerable attention in recent decades due to their outstanding characteristics. In the literature, most of the work is related to specific methods for the preparation of MXenes. In this Review, we present a detailed discussion on the synthesis of MXenes through different etching routes involving acids, such as hydrochloric acid, hydrofluoric acid, and lithium fluoride, and non-acidic alkaline solution, electrochemical, and molten salt methods. Furthermore, a concise overview of the different structural, optical, electronic, and magnetic properties of MXenes is provided corresponding to their role in supporting high thermal, chemical, mechanical, environmental, and electrochemical stability. Additionally, the role of MXenes in maintaining the thermal management performance of photovoltaic thermal systems (PV/T), wearable light heaters, solar water desalination, batteries, and supercapacitors is also briefly discussed. A techno-economic and life cycle analysis of MXenes is provided to analyze their sustainability, scalability, and commercialization to facilitate a comprehensive array of energy management systems. Lastly, the technology readiness level of MXenes is defined, and future recommendations for MXenes are provided for their further utilization in niche applications. The present work strives to link the chemistry of MXenes to process economics for energy management applications.

3D spacer fabric structured airflow channel for enhanced solar desalination with efficient multi-energy harvesting

Solar steam generation (SSG) is a sustainable way to drive seawater desalination and wastewater purification with green environmental energies including solar radiation, ambient heat, and airflow. Airflow is ubiquitous in outdoor environments, however, the utilization of airflow for accelerated evaporation through structure engineering remains unclear. Herein, environmental energies are efficiently utilized in an integrated way with the rational design of 3D spacer fabric. Carbon fiber bundles with broadband photothermal conversion ability and Tencel yarns with superior hydrophilicity are fabricated into the 3D spacer fabric. The stereoscopic airflow channel, wide evaporation surface area, and separated layers are constructed to optimize airflow pathways. Heat loss is reduced through the accelerated evaporation cooling effect. Extra ambient heat is harvested for cold evaporation by efficient airflow utilization. The evaporation rate of 3D spacer fabric reaches 5.15 kg·m−2·h−1 under a convective airflow of 3.5 m·s−1, which is twice the rate of traditional plain fabrics. The outstanding salt resistance is realized due to the separate design of photothermal and water supply layers as well as the continuous water circulation. The structural engineering of condenser devices is also investigated for enhanced airflow utilization. Overall, this work presents an effective and comprehensive multi-energy harvesting strategy to achieve rapid and durable SSG for practical clean water production.

A case study on single basin solar still augmented with wax filled metallic cylinders

This experimental study introduces a novel approach to enhancing solar still performance through the integration of wax-filled rods, marking a significant advancement in solar desalination technology. These rods, innovatively designed to absorb and store both sensible and latent heat during peak solar radiation hours, release this stored energy gradually, particularly during the evening and night. This unique mechanism results in a notable and consistent increase in water temperature within the modified solar still after 17:00, setting it apart from conventional models. The study's findings reveal that the modified solar still achieves a 12.8 % higher cumulative distillate yield and a 16.3 % increase in efficiency compared to traditional solar stills. Furthermore, this enhancement translates into a 6.3 % reduction in distillate production costs, underscoring the economic viability and superior performance of the modified design.

Lifetime optimisation of integrated thermally and electrically driven solar desalination plants

We compare the performance of photovoltaic (PV), flat-plate and evacuated-tube solar-thermal (ST), and hybrid photovoltaic-thermal (PV-T) collectors to meet the energy demands of multi-effect distillation (MED) desalination plants across four locations. We consider three scales: 1700 m3day−1, 120 m3day−1 and 3 m3day−1. We find a strong dependence of the capacity and configuration of the solar collectors on both the cost of sourcing electricity from the grid and the specific collector employed. We find specific costs as low as 7.8, 3.4 and 3.7 USDm−3 for the three plant capacities. We find that solar-driven systems optimised for the lowest specific cost result in CO2eq emissions equal to, or higher than, those from grid-driven reverse osmosis (RO) and in line with PV-RO. This highlights the need to consider the environmental footprint of these systems to ensure that desalination is in line with the United Nations’ Sustainable Development Goal 6.

Facile synthesis of carbon black and sodium alginate based particles system for efficient solar desalination of highly concentrated brine

Interfacial solar desalination of seawater/wastewater is one of the most promising strategies to mitigate the crisis of freshwater shortage. Tremendous progress on improving the evaporation rate has been achieved over the past ten years, however, with the rapid evaporation at the interfacial region of water and air, salt simultaneously aggregates on the solar absorbers, reducing the stability of the evaporative performance. It is essential to design salt-resistant solar evaporators, especially for dealing with highly concentrated brine, in which salt clogging is more likely to occur. Here, we demonstrate a facile and scalable synthesis of self-cleaning particles system by coating carbon black (CB) onto expanded polystyrene (EPS), which can generate freshwater from high salinity brine. With sodium alginate (SA) as a binder, the EPS core-CB shell particles are fabricated by a simple ‘rolling rice dumpling’ strategy. These particles spontaneously gather to a system in water attributing to the surface tension, which function coordinatively to realize the self-cleaning process through rotating ascribed to the unbalanced force after salt crystallization. Benefiting from the low cost of materials, facile synthesis procedure, and good performance in high salinity water, our EPS-CB particles system opens up an avenue for the practical applications of interfacial solar desalination.

Estimation of best geometric and operational parameters of a nanophotonics-enabled solar membrane desalination system: A numerical investigation

Nanophotonics-enabled solar membrane desalination (NESMD) system is a sustainable method to address water scarcity by desalinating seawater using solar energy. A layer of nanoparticles absorbs heat, creating localized heating within feed channel, which generates a vapor pressure difference between feed and permeate channels. Distillate water is collected in permeate channel. Numerical modelling of NESMD system, integrating optical and thermal modules in COMSOL Multiphysics, efficiently enumerates distillate flux at specified locations under varying ambient conditions. Reliability of the simulation model is confirmed through validation against in-house experimental results. A set of most effective dimensions and component specifications for NESMD system are computed that maximize distillate flux. Setup width exhibits invariant distillate flux within a range of 2–30 cm, while a feed thickness of 2 mm yields maximum distillate flux, with no change observed for permeate thickness within a range of 2–10 mm. An optimal setup length is determined within 80–200 cm range under varying operating conditions. Membrane porosity of 0.85 is selected to balance both vapor diffusivity and mechanical strength. The optimum membrane thickness lies within 180–225 µm range. An NESMD system with these best suited specifications is demonstrated to produce freshwater at the rate of 4.63 l/m2 per day.