Chapter 10 - Desalination and sustainability

Today, the issues of global warming and significant climate change are extremely relevant. They are discussed not only by scientists and politicians, but also by ordinary citizens. It must be understood that this problem really deserves extensive attention. Numerous studies have long confirmed that warming does have an impact on the environment, even at the regional level. If we leave some thoughts about extrapolation in the future, then the usually cited facts on local effects are easily verified by local residents, to a greater extent when it comes to melting permafrost or warm winters. In addition, biospheric effects relating to individual organisms are observed by all of us at the household level and therefore do not raise questions. In the modern world, the climate is changing under the influence of natural and anthropogenic factors. It seems to us that every person should want to preserve the natural conditions in which we live. Within the framework of this article, it is proposed to consider in more detail how this can be done.

Water scarcity represents one of the most critical environmental and economic challenges worldwide, especially in arid and semi-arid regions lacking access to reliable freshwater sources. In response, seawater desalination has emerged as a strategic solution to ensure a sustainable and secure supply of potable water for various applications. Among desalination technologies, Reverse Osmosis (RO) stands out for its high efficiency and widespread adoption, primarily due to its relatively low specific energy consumption compared to thermal-based methods. However, high operational costs particularly those related to energy consumption remain a barrier, as most conventional desalination plants rely on fossil fuels, contributing significantly to greenhouse gas emissions and environmental degradation. In this context, integrating renewable energy sources, specifically solar photovoltaic (PV) and wind energy, offers a viable pathway to reduce operational expenditures and minimize environmental impact. Several studies have demonstrated that hybrid renewable energy systems can enhance the sustainability and energy autonomy of desalination plants, aligning with Global Sustainable Development Goals (SDGs). This study conducts a techno-economic analysis of a Seawater Reverse Osmosis (SWRO) plant located in Al Wajh, Saudi Arabia. Detailed Capital expenditures (CAPEX) and Operational Expenditures (OPEX) were estimated for both conventional electricity-based operation and for configurations utilizing solar and wind energy in the same location. An energy simulation model was conducted to determine the optimal number of wind turbines required to maximize energy efficiency while minimizing excess power generation. The analysis revealed that the SWRO powered by renewable energy achieved an energy efficiency of 99%, compared to its conventional electricity-powered counterpart, with an energy surplus of no more than 4%. CAPEX and OPEX cost projections were calculated for both scenarios: conventional grid electricity and renewable energy sources. The findings indicated that the unit production cost per cubic meter of the SWRO plant was 0.59–0.76 $/m3 in the case of grid electricity, whereas it was 0.74–1.12 $/m3 under renewable energy integration. This cost disparity is primarily attributed to the higher CAPEX required for the renewable energy-powered SWRO system, which amounted to 0.28–0.36 $/m3, in contrast to a significantly lower CAPEX of only 0.06–0.09 $/m3 for the electricity-based SWRO configuration. Moreover, artificial intelligence (AI) was employed to support the results and forecast future water demand based on regional climate conditions and consumption patterns. The study concludes with a set of recommendations aimed at optimizing the integration of renewable energy technologies into desalination systems to enhance long-term economic and environmental sustainability.

Issues of global warming and climate change as a result of the aggravation of greenhouse gases and other anthropogenic activities have remained a global discourse since time immemorial. Climate change has increased temperatures and reduced the amount and distribution of rainfall. This has become a major concern to scholars and researchers alike. This study, therefore, investigates the impacts of climate change in the North Eastern part of Ghana between 1985 and 2016. The study looks at land use and land cover changes in the watersheds of the Tono Reservoir using satellite images. Satellite images were extracted and imported into ERDAS 2010 for processing. Layer stacking was performed to put all the bands together as one file. Sub-setting was done to extract the Tono Reservoir and its environs. Climate variables such as rainfall, temperature were analysed to find their relationships with water levels of the Tono reservoir. It was found that rainfall and water levels of the Tono reservoir were decreasing at 4.4% per decade and 8% per annum, respectively, while closed forests and grasslands had reduced by 5.51% and 7.44%, respectively, between 1985 and 2016. There were increases in open forests (2.8%), shrublands and bushes (0.97%) and water bodies (1.2%). The study recommends that collaborative efforts between the Ministry of Environment, Science, Technology and Innovation, Ministry of Water Resources, Ministry of Lands and Natural Resources and the Ministry of Food and Agriculture were necessary to safeguard natural resources in the country.

Factors influencing the electricity generation preferences of Turkish citizens: Citizens' attitudes and policy recommendations in the context of climate change and environmental impact

Chapter 4 - Solar-driven water treatment: generation II technologies

Preliminary thermoeconomic analysis of combined parabolic trough solar power and desalination plant in port Safaga (Egypt)

Although current water desalination technologies are mature enough and advanced, the shortage of freshwater is still considered as one of the most pressing global issues. Therefore, there is a strong incentive to explore and investigate new potential methods with low energy consumption. It is well-known that polymer hydrogel network has the ability to absorb water via swelling. In the case of polyelectrolyte hydrogels, the charges localized on the polymer chains, which mainly drive the swelling pressure inside the hydrogel, can also separate added salt via charge-based selectivity (Donnan exclusion). When combining this material with a temperature-sensitive polymer, the heat generated by solar energy can trigger the desorption process via conformational change of polymer chains. Hence, hydrogels designed from both materials, polyelectrolyte and thermo-responsive polymer can reduce the salinity of water, such as brackish water by means of reversible thermally-induced absorption and desorption desalination processes. In addition, the desorption process can also be achieved based solely on a polyelectrolyte hydrogel system by altering the ionization of charges within the hydrogel via pH. In this thesis, hydrogel-based water desalination process were developed using acrylic acid (AAc)/sodium acrylate (SA)-based polyelectrolytes as the charge-based separation function, alone or with a combination of N-isopropylacrylamide (NIPAAm) as thermo-responsive comonomer. In the latter case, a series of chemically cross-linked polymeric hydrogels were synthesized via either free radical-initiated copolymerization or reversible addition-fragmentation chain transfer (RAFT) polymerization, thus realizing different macromolecular architecture. According to the nature of hydrogels, the reversible sorption/desorption state were triggered by either chemical stimulus (pH), or physical stimulus (heat) as the thermo-responsive polymer introduced into the hydrogels. In detail, the effect of hydrogel composition as well as the influence of the macromolecular architecture on the swelling/deswelling behavior for the synthesized hydrogels were studied. For this, their properties including their responses to external stimuli were investigated, and their ability to desalinate brackish water as well as the effciency of such desalination process were evaluated. Generally, the results demonstrated correlations between macromolecular architecture of the network structure and their performance in the proposed desalination process, such as salt rejection and desalination capacity. Moreover, the potential of the best performance materials for applications was also discussed.

Nuclear power can be categorized as a clean energy source for producing electricity and supplying the required energy to a desalination plant, promising less atmospheric emission in comparison to fossil fuels. Considering the fact that fresh water-related issues are acute in many countries of the world, the utilization of desalination technologies seems to be the key solution to these problems. Desalination processes are known to be “energy-intensive”, emphasizing the potential advantages of its integration to a nuclear power plant in mediumto large-scale seawater desalination projects. The demand for electricity and fresh water in Iran compels the country to search for a feasible option. We suggest nuclear desalination as a suitable alternative, in which the recovered heat can be used in thermal desalination systems. In this article, the status of currently operating desalination plants and future developments are described. Several possible schemes for coupling nuclear power plant and fossil fuel-based plants with desalination technologies are suggested and some thermo-economic analysis (based on the specific characteristics of the country) are presented. Results of calculations reveal some advantages of nuclear desalination complex and its competitiveness with other options. It should be noted that the research has been conducted by cooperation of two SPbPU PhD students with Iranian citizenship.

Analytical study of optimum operating conditions in semi-batch closed-circuit reverse osmosis (CCRO)

Development of novel desalination technologies is driven by the global need for efficient, sustainable water treatment solutions amid increasing water and energy demands. Zinc–air desalination batteries (ZADBs) offer a dual advantage by both desalinating brackish water and generating energy, positioning them as promising alternatives to traditional methods. This study evaluated a ZADB for brackish water treatment, focusing on its desalination performance under varying salinity, composition, current, and catholyte concentrations. The ZADB setup included a zinc anode, anion and cation exchange membranes, and an air cathode. Results showed a salt rejection rate of 98.5% at 2500 ppm of NaCl solution, which decreases to 59.7% at 7500 ppm, indicating that high salinity challenges the desalination process due to ion interactions. Increasing the current from 1 mA to 2 mA improved salt removal rates, particularly at higher salinities. Testing different catholyte concentrations revealed no adverse effect on the desalination performance, maintaining high salt rejection and stable charge efficiency. Moreover, the results showed that the system can desalinate solutions other than NaCl (i.e., LiCl and Na2SO4). Furthermore, the use of oxygen nanobubbles in the catholyte led to an approximate 12% improvement in salt rejection, attributed to the elevated dissolved oxygen concentration (~ 36 ppm) compared to the baseline condition (8.6 ppm). The study highlights the ZADB's potential for treating saline water, with optimized conditions improving energy conversion and salt removal efficiency, supporting its viability for sustainable desalination applications.

The inclusion of clays in concrete not only reduces the production of Portland cement (PC) and the consumption of raw materials but also offers an alternative to PC that can significantly lower CO2 emissions during calcination, along with requiring relatively less thermal energy compared to PC production. This effect can considerably reduce global warming and climate change issues. This paper reviews the effect of calcined clay (CC) substitution, particularly calcined bentonite (CB) and metakaolin (MK), on the fresh (including reaction characteristics), fundamental mechanical, and durability (including permeability, and acidic and corrosion attack resistance) properties. The economic and sustainability analyses are also conducted. Finally, their practical applications in infrastructure construction to produce sustainable and green concrete are reviewed. Initially, a systematic analysis was performed on statistical data available on the Scopus database to study the detailed census of the published data and the same data was imported into VOSviewer software to draw network visualization charts.

The world is facing the challenge of global warming and climate change issues. The objective of the study is to examine the meteorological data that constitute the environment and their balance has prevailing effect on the global warming. The meteorological data in our study refers to temperature, humidity, carbon dioxide and oxygen. We deploy our own customized hardware setup to obtain the data. Provided with this basic data, many significant parameters such enthalpy, dew point, humidity ratio, actual vapor pressure, saturated vapor pressure, partial vapor pressure and specific volume could be derived. We have presented simple functions in Matlab programming to derive these parameters. Our concluding Matlab program is as good as calculator, and the output is visualized by plotting function.

Due to growing cooling demands as well as emerging global warming and climate change issues, cooling systems should be more efficiently utilized. Boiling is an effective heat transfer mechanism, which has a critical role in many cooling systems. Surface modification is considered as the major approach for boiling heat transfer enhancement. In this study, we developed a microbial bio-coating surface modification technique for phase change cooling applications. Thermoacidophilic Sulfolobus solfataricus coating was implemented using a facile dip coating method on different metallic and non-metallic surfaces. Controlled by drying conditions, the coating exhibited rough and porous morphologies. When tested in a boiling heat transfer setup, bio-coated surfaces offered enhancements up to 76.3% in Critical Heat Flux (CHF). Next, a miniature evaporator was coated and tested for real-world air-conditioning applications, and coefficient of performance (COP) enhancements up to 11% clearly revealed the potential of bio-coated surfaces for energy saving purpose and reduction in greenhouse gasses. Furthermore, coated evaporators reduced the exergy destruction rate up to 8%. This study not only offers a new type of coating morphology, but the applicability of the proposed bio-coating is also proven in a miniature air conditioning system.

A hybrid power system is becoming more attractive for power generating applications as renewable energy technologies progress and oil prices rise. A hybrid power system may consist of only conventional sources of energy, only non-conventional sources of energy sources, or both conventional and non-conventional sources of energy. This work illustrates the study and optimization of a hybrid power system in the Chhota Nagpur plateau region using one conventional and one renewable energy source by developing its Simulink model using MATLAB software and also deals with economic and environmental aspects of the system. This paper presents a hybrid power system based on photovoltaic (PV) and a conventional diesel generator equipped with a DC-DC boost converter, three-phase inverter, and filter. During this work, the authors found that the use of non-conventional sources with conventional sources for power generation increases the reliability and affordability of the system. The findings suggest that this hybrid system is also environmentally friendly as it has the potential to restrict the emission of a significant number of harmful gases in the environment. India is committed to reducing its carbon emission by one billion tons from now onwards till 2030. India is also committed to fulfilling its half its energy demand from renewable energy by 2030. The hybrid power system may help to achieve this target.

Optimization techniques for coupling renewable/hybrid energy options with desalination systems for carbon footprint reduction