Exergy Analysis of a Two-Pass Reverse Osmosis (RO) Desalination Unit with and without an Energy Recovery Turbine (ERT) and Pressure Exchanger (PX)

Eshoul, NM; Agnew, Brian; Al-Weshahi, MA; Atab,

doi:10.3390/en8076910

Cited by 30 publications

(13 citation statements)

References 24 publications

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“…This compares to water losses of 50%-80%, which are associated with conventional desalination plants [18][19][20][21][22][23].…”

Section: D31 Observed Water Volume Reductionmentioning

confidence: 99%

“…is typically within the range of 20%-50% of the feed water [18][19][20][21][22][23]. The residual enhanced salinity waste water (reject brine) is discharged into the environment [18][19][20][21][22][23]. The discharged waste water volume is in the order of 50%-80% of the feed water volume [18][19][20][21][22][23].…”

Section: D3 Significance Of Water Volume Reductionmentioning

confidence: 99%

Section: D3 Significance Of Water Volume Reductionmentioning

confidence: 99%

“…A reverse osmosis (RO) desalination plant producing 600-500,000 m 3 /day requires an external energy source, which is in the range of 2.5-9.38 kWh/m 3 of product water [18,19]. Similar amounts of external energy are required for each of the alternative desalination technologies (e.g., mechanical…”

Section: Introductionmentioning

confidence: 99%

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ZVI (Fe0) Desalination: Stability of Product Water

Antia¹

2016

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A batch-operated ZVI (zero valent iron) desalination reactor will be able to partially desalinate water. This water can be stored in an impoundment, reservoir or tank, prior to use for irrigation. Commercial development of this technology requires assurance that the partially-desalinated product water will not resalinate, while it is in storage. This study has used direct ion analyses to confirm that the product water from a gas-pressured ZVI desalination reactor maintains a stable salinity in storage over a period of 1-2.5 years. Two-point-three-litre samples of the feed water (2-10.68 g (Na + + Cl´)¨L´1) and product water (0.1-5.02 g (Na + + Cl´)¨L´1) from 21 trials were placed in storage at ambient (non-isothermal) temperatures (which fluctuated between´10 and 25˝C), for a period of 1-2.5 years. The ion concentrations (Na + and Cl´) of the stored feed water and product water were then reanalysed. The ion analyses of the stored water samples demonstrated: (i) that the product water salinity (Na + and Cl´) remains unchanged in storage; and (ii) the Na:Cl molar ratios can be lower in the product water than the feed water. The significance of the results is discussed in terms of the various potential desalination routes. These trial data are supplemented with the results from 122 trials to demonstrate that: (i) reactivity does not decline with successive batches; (ii) the process is catalytic; and (iii) the process involves a number of steps.

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“…This compares to water losses of 50%-80%, which are associated with conventional desalination plants [18][19][20][21][22][23].…”

Section: D31 Observed Water Volume Reductionmentioning

confidence: 99%

Section: D3 Significance Of Water Volume Reductionmentioning

confidence: 99%

Section: D3 Significance Of Water Volume Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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ZVI (Fe0) Desalination: Stability of Product Water

Antia¹

2016

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“…The desalination process has substantial potential to provide new fresh water from non-conventional resources such as seawater, which accounts for over 97% of the total water. Although desalination by thermal process, such as distillation, is still popular in areas with plentiful energy sources, reverse osmosis (RO) desalination has now been highlighted as a clean technology by using membranes rather than consuming fossil fuels directly (Charcosset, 2009, Eshoul et al, 2015, Shenvi et al, 2015.…”

Section: Introductionmentioning

confidence: 99%

A computational approach to evaluation of nanoporous zeolitic membranes for reverse osmosis desalination

Han¹

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Water scarcity has become one of the major global concerns. Research has shown that more than one-third of the population throughout the world resides in water-stressed regions now.Reverse osmosis (RO) desalination has recently been highlighted as a clean technology that is less energy intensive using membranes rather than directly consuming fossil fuels.Advances in nanomaterials have opened new possibilities for RO membrane materials. Zeolites are one of the candidate materials due to their crystalline structures and durability. However, the performance of zeolite membranes has not been successful for practical use due to poor water flux.Thus, we used molecular dynamics simulations to investigate, at the molecular level, a series of potential zeolite types which have been rarely studied for application in desalination. We determine diffusion coefficients and the structure of water when it passes through pores of these zeolites. In addition, we examine the potential of mean force for water or ions as they move into and through a zeolite membrane in order to evaluate how favourable the passage of the molecule of interest through each membrane is. This provided us with some criteria (i.e. water permeability and ion selectivity) to judge if the membrane is likely to have suitable desalination performance. Without this molecular-level understanding, selection of zeolite materials for desalination membranes is difficult.Some widely-studied types and potential types of zeolites were selected for our study. The common types have all 3-dimensional (3-D) pore structures, while the potential zeolites have 1-dimensional (1-D) cylindrical pores. To investigate the water dynamics and structure in these different pores, we employed molecular (MD) dynamics simulations. The MD results showed the water self-diffusivity, which indicates a molecular mobility, in the 1-D pores is up to 18-time higher than that of the 3-D pores. As it was found that water molecules formed clusters, water droplets, and moved collectively at low water density in the zeolite pores, the water collective diffusivity, which is directly related to water flux, was also measured for the all the case of zeolites. This collective diffusivity through the 1-D pore zeolites was around one order of magnitude higher than that of the 3-D pore zeolites, suggesting our 1-D zeolites selected are promising as high flux membranes.To evaluate the thermodynamic stability for water or ion of interest when they pass across the zeolite membranes, the potential of mean force calculations were carried out using MD simulations.We selected one of the 3-D pore zeolites (LTA) and another of the 1-D pore zeolites (VET) for the membrane. In general, these membranes had a moderate energy barrier to water transport, but a very high barrier to sodium or chloride ion transport except the VET membrane. The chloride ion ii had a minimum in the potential of mean force at the pore entrance and a preference for the chloride ion to enter the pore than to enter the bulk solution for the...

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Addressing Freshwater Scarcity and Hydrogen Production: Offshore Wind and Reverse Osmosis Synergies

Ishaq,

Crawford

2024

Advanced Sustainable Systems

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The transition from fossil fuels to renewable energy sources is imperative to mitigate climate change and achieve sustainable development goals (SGDs). Hydrogen, as a clean energy carrier, holds great potential for decarbonizing various sectors, yet its production remains predominantly reliant on fossil fuels. This study explores a novel approach to sustainable hydrogen production by integrating offshore wind energy with reverse osmosis (RO) desalination technology. The proposed configuration harnesses offshore wind power to energize both a RO desalination system and water electrolysis unit. Initially, the wind energy powers the RO desalination process, purifying seawater, and then desalinated water is directed to water electrolysis system for generating green hydrogen directly from seawater. The resulting renewable hydrogen holds potential for diverse applications, including marine industries, and can be transported onshore as needed. The RO system is configured to treat 20 kg s−1 of seawater with a salinity of 35 000 ppm, aiming for a high recovery ratio and reduced freshwater salinity. A pressure exchanger (PX) is integrated to recover energy from high‐pressure brine stream and transfer it to the low‐pressure feed water, thus reducing the overall energy consumption of the RO process. The concentrated brine extracted from RO desalination is proposed to be utilized for the production of sodium hydroxide that can further pretreat incoming seawater and enhance the effectiveness of the filtration process by mitigating membrane fouling. This pressure exchanger increases the energy efficiency of the RO system from 63.1% to 64.0% and exergetic efficiency from 13.9% to 18.2% increasing the overall first and second law efficiencies to 37.9% and 33.5%. By leveraging offshore wind power to drive RO desalination systems, this research not only addresses freshwater scarcity but also facilitates green hydrogen generation, contributing to the advancement of renewable energy solutions and fostering environmental sustainability.

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Exergy Analysis of a Two-Pass Reverse Osmosis (RO) Desalination Unit with and without an Energy Recovery Turbine (ERT) and Pressure Exchanger (PX)

Cited by 30 publications

References 24 publications

ZVI (Fe0) Desalination: Stability of Product Water

ZVI (Fe0) Desalination: Stability of Product Water

A computational approach to evaluation of nanoporous zeolitic membranes for reverse osmosis desalination

Addressing Freshwater Scarcity and Hydrogen Production: Offshore Wind and Reverse Osmosis Synergies

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