Low energy desalination and wind energy — sustainable solutions for drinking water production

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.

The demand on energy supply increases continuously as economies develop and world population grows. Most of the energy in the world comes from the fossil fuels and the increase in energy demand accelerates the rate of depleting the fossil fuel resources. As fossil fuel is finite and also due to the environmental considerations, renewable energy (RE) resources have been actively developed as the alternative sources for electricity generation. Renewable sources used for large-scale electricity production can include wind, photovoltaic (PV), waves and so on. Among all the RE resources, wind power generation is witnessing rapid developments in recent years. Unfortunately, wind tends to be unsteady. The fluctuating and uncertain output powers from wind farms can be problematic, especially if there is a high penetration level of the renewable source in a grid system. The fluctuations may lead to excessive voltage variations and unacceptable degree of frequency deviations. Moreover, the unsteady and uncertain input wind power can cause firm power dispatch commitment from wind farms a difficult task. Expensive generation reserves have to be provided for grid system to ensure adequate level of system security and reliability is guaranteed. In fact, power generation from wind farms has often been excluded in the dispatch planning of the grids. Unless other viable techniques can be found, the above issues can constitute major impediment to the successful large-scale integration of wind power generation into grid systems. In this connection, the use of energy storage system (ESS) is one possible solution to mitigate the negative impacts of the unsteady wind power on electricity supply systems and to improve on the dispatchability of the wind power. In this investigation, in order to smoothen the fluctuations in the wind and to realize the dispatch planning of the wind power in a way similar to that of conventional generators, it is proposed that a three-level ESS is incorporated in a large-scale wind power generation scheme. In essence, at cluster-level of wind turbine generators (WTG), the solution involves having the high- and mid-frequency components of the aggregated wind power routed to supercapacitors (SC) and battery banks respectively of a battery-supercapacitor hybrid energy storage system (BSHESS) by a high-pass filter (HPF) and a band-pass filter (BPF). It then results in the smoothening of the wind power harnessed by the cluster. In this thesis, the BSHESS control scheme to reduce the wind power perturbations has been shown. A statistical method is also developed to determine the capacities of the minimum-cost BSHESS to meet the power smoothing objective at pre-specified probability level. Application of the proposed design approach is demonstrated using data obtained from an existing wind farm. As for dispatch planning, attention is to use a low-pass filter (LPF) to extract the low-frequency intrinsic mode and residue functions of wind power. The relatively slow-changing characteristics of the low-frequency wind power components, which contain most of the energy in the wind power, allow accurate forecasts of the power components to be obtained using artificial neural network (ANN). Dispatch planning of the wind power is then realized through buffering the low-frequency power fluctuations by a proposed power flows control strategy applied to a pumped hydroelectric storage (PHS) system. Focusing on low-frequency wind power for dispatch planning is a distinct advantage over the dispatch planning methods proposed by other researchers. Furthermore, a statistical method to determine the power and energy capacities of the PHS is included. The efficacy of the developed approach to dispatch planning is again illustrated based on data obtained from an existing wind farm. In all the above works, suitable cut-off frequencies for the HPF, BPF and LPF are derived based on the developed concept of minimum overlap energy and the outcome of empirical mode decomposition (EMD) analysis. EMD method is used to gain insights into the frequency-time characteristics of wind power. In this manner, the wind power can then be grouped into high-, mid- and low-frequency bands.

Optimal design of a hybrid solar-wind power to drive a small-size reverse osmosis desalination plant

Impact of desalination plants fluid effluents on the integrity of seawater, with the Arabian Gulf in perspective

Energy-related concerns about traditional resources include the depletion of fossil fuel, a dramatic increase in oil prices, the global warming effect caused by pollutant emissions from conventional energy resources, and the increase in the energy demand. These concerns have resulted in the recent remarkable growth of renewable energy industries [1-3]. Furthermore, renewable energy has become a significantly important research area for many researchers as well as for governments of many countries as they attempt to ensure the safety, long-term capability, and sustainability of the use of global alternative energy resources [2]. Renewable energy resources include solar, geothermal, wind, biomass, ocean, and hydroelectric energy. [4] In particular, both solar (i.e. photovoltaics) and wind energy are considered to be leading technologies with respect to electrical power generation. The study of photovoltaics (PV) has been carried out since the 1980s’ and is currently the most significant renewable energy resources available. According to the Renewable Energy Policy Network for the 21st Century (REN21), there has been a strong growth in the use of PV of 55 % and the worldwide solar PV electric capacity is expected to increase from 1,000 MW in 2000 to 140,000 MW by 2030 [5]. Moreover, it is forecast by the European Renewable Energy Council that this renewable electric energy could become sufficient to cover the base load and half of the global electricity energy demand by 2040 [6]. Generally in the PV industry, crystalline silicon has generally occupied about 95 % of the market share of materials, while only 5 % of all solar cells use amorphous silicon [7]. However, in order to improve the cost efficiency of solar cells by using less material, the thin-film PV module with amorphous silicon has become an active research and development (R&D) area [8]. In particular, solar cells that use amorphous silicon have the advantage of being able to generate a higher energy output under high temperatures than crystalline silicon solar cells, which are less affected by the temperature increase with respect to performance of electricity output than are the crystalline silicon solar cells. Moreover, installed at the rooftop and on the exterior wall of the building, a thin-film solar cell can be conveniently used as a facade that generates power for the entire building. This system is known as a building integrated photovoltaic system (BIPV). The thin-film solar cell can also provide the advantage of heat insulation and shading when incorporated into a harmonious building design. Therefore, the thin-film solar cell is expected to be a very bright prospect as a new engine for economical growth in the near future. Currently in Korea, many researchers are conducting

Economic optimization of the number of effects for the multieffect desalination plant

Integrated membrane systems for seawater desalination: energetic and exergetic analysis, economic evaluation, experimental study

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.

Development of renewable energy systems can certainly contribute to climate change mitigation. In many regions initiatives can be noticed to succeed in increasing the efficient usage of renewable energy resources such as hydro power, solar and wind energy as well as bioenergy. From these resources the bioenergy and the hydro power by their storage possibilities have the potential to counterbalance the temporal variability of solar and wind energy. Anyway, by applying such renewable energy resources it is possible to meet sustainable future national energy-related advisory goals and mitigate CO2 emissions as foremost objective of energy sector strategies on European level. The innovative thinking way of humanity has always been driving the field of shaping more efficient energy supply systems with less negative environmental impacts. The impacts of conventional energy supply systems, especially based on fossil fuels, have been long-perceivable especially on the environment. In the meanwhile, it has become clear that the usage of fossil fuels for operating energy supply systems does not represent a long-term solution. Renewable energy resources, like water, wind and solar energy, must be more used in the future by considering their sustainable usage odds being needed a holistic analysis and assessment by applying methods and instruments of Technology Assessment. In this paper proposal a case study in a region of Republic of Moldova will be presented, where the design of a wind energy-based energy supply system is planned for mitigating climate change. After debating the relevance of technical aspects besides environmental related criteria regarding shaping odds of a wind farm in concrete Moldavian conditions, corresponding environmental aspects will be debated as well as future usage odds of wind energy on a regional level.

Renewable energy resources such as offshore wind and wave energy are environmentally friendly and omnipresent. A hybrid offshore wind-wave energy system produces a more sustainable form of energy that is not only eco-friendly but also economical and efficient as compared to use of individual resources. The objective of this paper is to give a detailed review of co-generation technologies for hybrid offshore wind and wave energy. The proposed area of this review paper is based on the power conversions techniques, response coupling, control schemes for co-generation and complimentary generation, and colocation and integrated conversion systems. This paper aims to offer a systematic review to cover recent research and development of novel hybrid offshore wind-wave energy (HOWWE) systems. The current hybrid wind-wave energy structures lack efficiency due to their design and AC-DC-AC power conversion that need to be improved by applying an advanced control strategy. Thus, using different power conversion techniques and control system methodologies, the HOWWE structure can be improved and will be transferrable to the other hybrid models such as hybrid solar and wind energy. The state-of-the-art HOWWE systems are reviewed. Critical analysis of each method is performed to evaluate the best possible combination for development of a HOWWE system.

Desalination powered by a microgrid is becoming an important task for a large number of countries with water shortage. Even with countries in sufficient supply of water from the nature, desalination is crucial for residents in remote and isolated regions such as islands. Production capacity of a desalination plant depends on the number of beneficiaries. When the number of beneficiaries is on the order of 100, microgrid based desalination plant can be a competitive solution. This work presents a desalination process conducted in a microgrid based desalination management platform. Desalination plant operated by renewable energy is implemented and tested. Since most of electric power consumed in the platform is used for high pressure pump, it is our main concern to observe the relation between the high pressure pump and other controllable device(s), e.g., the retentate valve. It is found from the observations that the retentate valve can affect the operation of desalination process by means of its openness.

Many regions in the world exhibit temporal complementarity of solar and wind energy. In such regions, during certain time periods, when more solar energy is present, lesser amount of wind energy is available and vice-verse. The motivation of this work is to develop a general planning methodology for the integration of these variable renewable energy (VRE) resources in smart power grids, while exploiting temporal complementarity to minimize the supply demand mismatch. We develop an appropriate analytical framework to determine the total investment needed in such VRE resources and the fraction of the total investment in each resource. A multivariate optimization problem is formulated and an optimal algorithm is developed to determine these parameters. To test the proposed methodology, a case study is developed for a region in Northern Ireland. In this region, based on the historical data of past 10 years and using daily average wind and solar capacity factors, we determine the Pearson correlation coefficient, which turns out to be −0.34, showing a sufficient degree of complementarity (anti-correlation) between solar and wind energy. Planning parameters are determined for different load profiles in our case study. General conclusion of the work is that once the temporal complementarity of solar and wind energy resources is exploited, the net supply variability is significantly reduced in microgrids. However, the total investment costs also increases, which is offset by the savings in the storage costs. In addition, reduced variability also leads to a reduction in storage losses, emissions losses, dispatch losses, fuel costs and network congestion.

Climate change and water scarcity has pushed more countries with direct ocean access to seek desalination solutions to face part of their need for domestic water networks or industrial usage, while conserving coastal ecosystems. Seawater monitoring is crucial in implementing a desalination plant as it ensures the efficiency and sustainability of the desalination process, especially in the case of a plant powered by renewable energy sources. Seawater is the main input of desalination processes and coastal areas are the locations of the release of the salty waste. An autonomous buoy can be used to monitor the seawater parameters which are essential to sizing a desalination plant.There have been recent developments of autonomous buoy systems for monitoring different water parameters, however lacking in certain aspects. Some of the elements of these buoys include limited range of data transmission, high-cost designs, immobility and limited number and types of sensors. Also, there has been lacking implementation of autonomous buoys used in development of desalination plants. The proposed low-cost autonomous buoy is designed and constructed using cost effective materials. It increases the possibility of multiplying the sensor count to have a more accurate data mapping system. The low cost provides the opportunity of having more devices where there is a higher probability of equipment loss due to possible theft or remoteness of travel. The power supply is an oversized solar array with a backup battery and solar charger. An Arduino microcontroller is connected to two probes and a GPS sensor. The data is logged on a SD memory card with data transmitted via the Iridium satellite constellation, consisting of 75 satellites. There are two parts of construction involved in the project: the construction of the outer shell of the buoy and the design of the inner circuitry and components. The project involves multiple steps of experimentation: first in a laboratory/controlled area then deployed in the Seto Inland Sea, Japan. The various steps ensure the data collected by the sensors is reliable, valid, and suitable for scientific research. After this successful implementation, the buoy will be adapted and deployed in the Caribbean Sea surrounding Jamaica.Initial results show a promising possibility of measuring seawater parameters such as GPS location, salinity, and sea surface temperature for any body of water. Utilizing the span of the Iridium satellite communication system, this ensures that virtually all regions of the Earth can be measured. The sizing of the solar powering components allows for at least 1 year of monitoring in the worst-case scenario and 4-5 years in the best-case scenario. The integration of autonomous buoys in the desalination process enhances efficiency in the plant design stages and reduces potential costs which contributes to the optimization of the desalination system. The environmental integration and the operation of the plant will be improved as a result of the enhanced assessment of the input and waste release conditions. Keywords: Seawater Monitoring, Remote Sensing, Desalination, Autonomous buoy, Autonomous measurements 

The largest source of energy currently utilized is still predominantly from fossils. Fossil energy sources are non-renewable so over time they will run out. So it is necessary to utilize renewable energy sources. One renewable energy source that is environmentally friendly and easy to obtain is wind energy. Wind is a collection of air that is experiencing movement due to a difference in pressure on the earth's surface. Wind will move from areas of high pressure to areas of lower pressure. Experimental research on wind energy is a useful energy that can be put to good use. Wind energy is a form of energy that comes from utilizing air flow in the atmosphere to produce mechanical or electrical energy. The main technology used to utilize wind energy is a wind turbine, which converts wind kinetic energy into electrical energy through a generator. Which of course also requires sufficient wind speed so that the wind turbine can rotate and produce mechanical movement in the form of rotational torque which can then be converted into electrical energy. Wind energy has great potential as a clean, sustainable and environmentally friendly resource, as it does not produce greenhouse gas emissions or hazardous waste during its operation. However, wind energy development faces challenges such as fluctuations in wind speed, large land requirements, visual impacts, and potential disruption to local ecosystems. With technological innovation and careful planning, wind energy can be a significant solution to meet global energy needs in a sustainable manner.

The research addressed the economic evaluation of nuclear energy, coal, oil and natural gas in various cycle configurations with different distillation technologies. A comparison between fossil and nuclear energy sources is discussed. A comprehensive review of all desalination plants using fossil and nuclear energy with cogeneration is also included and discussed. Computational model was used to evaluate nuclear and non-nuclear desalination plants. Four possibilities were discussed. In this first case, a nuclear gas cycle integrated with a MED desalination plant was found to have the lowest cost in the gas cycle. While the nuclear steam cycle integrated with RO has the lowest cost compared to oil and natural gas. In the third case, the combined nuclear cycle was discussed and it was found that the combined nuclear cycle associated with RO has the lowest cost. In the last case, the evaluation of a heat-only desalination plant was conducted among all sources, and it was found that the nuclear plant with RO and MED has the lowest cost. In addition, the completed nuclear desalination plant was subjected to five scenarios to calculate and estimate at which capacity the plant provides the best values. The results show that nuclear desalination with gas cycle is the most economical among the oil and natural gas options.