Photovoltaic Electrodialysis Research Articles

Photovoltaic electrodialysis makes brackish water treatment simpler

Photovoltaic electrodialysis makes brackish water treatment simpler

Direct-drive photovoltaic electrodialysis via flow-commanded current control

Renewable powered, brackish groundwater desalination is an underutilized resource in the developing world, where there are unreliable energy sources and reliance on increasingly saline groundwater. Traditional renewable desalination technologies require sizable energy storage for sufficient water production, leading to increased cost, maintenance and complexity. We theorize and demonstrate a simple control strategy—flow-commanded current control—using photovoltaic electrodialysis (PV-ED) to enable direct-drive (little to no energy storage), optimally controlled desalination at high production rates. This control scheme was implemented on a fully autonomous, community-scale (2–5 m3 d−1) PV-ED prototype system and operated for 6 months in New Mexico on real brackish groundwater. The prototype fully harnessed 94% of the extracted PV energy despite featuring an energy storage to water productivity ratio of over 99% less than the median PV desalination systems in literature. Flow-commanded current control PV-ED provides a simple strategy to desalinate water for resource-constrained communities and has implications for decarbonizing larger, energy-intensive desalination industries.

Performance study on a small-scale photovoltaic electrodialysis system for desalination

A small-scale photovoltaic (PV) direct drive electrodialysis system is proposed to explore the factors affecting the desalination performance. The electrodialysis desalination model is established, and is solved using MATLAB to investigate the influences of voltage, flow rate and electrolysis compartment size on performance factor β. This model is proved valid to predict the characteristics of photovoltaic electrodialysis system. The results show that the salinity at exit of the electrodialysis chamber decreases with the increase of the voltage and the ion membrane area, and increases with the increase of the flow rate. In typical sunny day, the salinity reaches below the standard value (<1000 ppm) by 20 minutes and 60 minutes earlier than in cloudy day and in overcast day, respectively. During the experiments, the cumulative freshwater is respectively 0.4L, 1L, 1.6L and 2.2L within 120 minutes at different flow rate.

Experimental study on liquid desiccant regeneration by photovoltaic electrodialysis

Abstract Liquid desiccant regeneration is an important part of liquid desiccant air conditioning system and consumes the majority of the system’s power. Conventional methods for liquid desiccant regeneration use thermal energy to regenerate the liquid desiccant. One of the biggest problems for thermal regeneration is that the liquid desiccant should be cooled down before dehumidification. Furthermore, the efficiency for liquid desiccant regeneration drops under high temperature and humidity climates. In comparison, electrical regeneration, such as electrodialysis (ED), may solve the problems above. No phase change is involved in this process. In addition, low electrical energy is required and photovoltaic power is capable of proving the necessary energy. In this paper, the performance of liquid desiccant regeneration by photovoltaic electrodialysis (PV-ED) was experimentally investigated by considering two important factors, including the initial desiccant concentration and current intensity. The results showed that the initial desiccant concentration and current intensity had big impact on the performance of the system. Lower desiccant concentration and higher current intensity contributed to the current efficiency and solute transport, respectively. In addition, the energy consumption per unit solute migration increased with the increase of both current intensity and desiccant concentration. The results also indicated that the PV-ED regenerator performed better when the initial desiccant concentration was low and current intensity was high.

Design and testing of an isolated commercial EDR plant driven by solar photovoltaic energy

abstract The production of potable water from brackish water, tertiary treatments of treated wastewaters for irrigation and other allowed uses, and several industrial processes which use recycled water are the most important applications of electrodialysis (ED). During the last years, the number of pilot initiatives focused on renewable energy powered desalination has grown, being one of the most promising combinations of the ED powered by photovoltaic (PV) systems. ED combined with renewable energies becomes attractive for being a mature technology, which requires direct current (DC) power and is easily adapted for variable energy conditions. The present paper shows the design, installation, testing, and monitoring of a 100% isolated PV–ED system which is feasible for a commercial scale. The testing tasks have been performed in a 4 m3/h commercial-one stack electrodialysis reversal plant powered by two solar PV fields in parallel. For the DC energy required in the stack, a solar PV field has been designed and tested. It permits modulation by different solar panels connections, and thus makes possible to maintain the output current according to the real solar radiation and different raw water salinity.

Double-stage photovoltaic/thermal ED regeneration for liquid desiccant cooling system

Photovoltaic-electrodialysis (PV-ED) regeneration is a novel method for liquid desiccant cooling system (LDCS), which has a higher performance than the conventional thermal regeneration method by using solar photovoltaic components to drive an electrodialysis regeneration process. However, there are many defects in the previous proposed single-stage PV-ED system. In this paper, a new double-stage photovoltaic/thermal ED regeneration system is presented. Analysis of the performances of the single-stage and double-stage regeneration system is made and the influential factors are investigated. It reveals that the double-stage PVT-ED regeneration system is more applicable than the single-stage PV-ED regeneration system for liquid desiccant cooling system. Moreover, comparisons between the single-stage system and the double-stage system show that the double-stage system is more energy efficient than the single-stage system under the optimized working conditions.

Single-stage and double-stage photovoltaic driven regeneration for liquid desiccant cooling system

Liquid desiccant cooling system (LDCS) is a novel air-conditioning system with good energy saving potential. However, the present LDCS has a poor performance, mainly because the conventional thermal regeneration method wastes too much energy during the regeneration process. To improve that, photovoltaic-electrodialysis (PV-ED) regeneration method is introduced: it has a higher performance by using solar photovoltaic panels to drive an electrodialysis regeneration process. To further explore the PV-ED method, both single-stage and double-stage photovoltaic-electrodialysis regeneration systems are presented in this paper. Analysis is made on these two systems and some influential factors are investigated. It reveals that the concentration difference between the desiccant solution before and after regeneration has a strong impact on system performance. Moreover, comparison is conducted between the single-stage and the double-stage systems, the results show that the double-stage system is more energy-efficient and it can save more than 50% energy under optimized working conditions.

Photovoltaic–electrodialysis regeneration method for liquid desiccant cooling system

Liquid desiccant cooling system (LDCS) is an (a novel) air-conditioning system with good energy saving potential. Regenerator is the power centre for LDCS. Currently, the regeneration process is always fuelled by thermal energy. Nevertheless, this regeneration pattern has some disadvantages in that its performance will become poor when the surrounding atmosphere is of high humidity, and the heat provided for regeneration will be unfavourable to the following dehumidification process. To ameliorate that, a new regeneration method is proposed in this paper: a membrane regenerator is employed to regenerate the liquid desiccant in an electrodialysis way; while solar photovoltaic generator is adopted to supply electric power for this process. Analysis has been made about this new regeneration method and the result reveals: this new manner achieves good stability with the immunity against the adverse impact from the outside high humidity; its performance is much higher than that of the thermal regeneration manner while putting aside the low efficiency of the photovoltaic system. Besides, purified water can be obtained in company with the regeneration process.

Photovoltaic electrodialysis system for brackish water desalination: Modeling of global process

The shortage of drinking water is a major problem in the South East of Spain. In these areas, it is essential to make use of water from underground reservoirs, most of which are over exploited and suffer from saline contamination given their proximity to the sea. The desalination of brackish water is a means of obtaining low cost drinking water. The method of desalination designed in this paper uses an electrodialysis system fed by photovoltaic modules that is simple, reliable, and low cost because it does not include battery storage or a battery regulator. These systems are of particular interest for isolated zones with access to wells of brackish water where connection to the electric grid is not possible. In this paper, the feasibility of the desalination of brackish water using an electrodialysis system powered by photovoltaic energy and the influence of experimental parameters has been studied. Likewise, a mathematical simulation model that allows predicting and simulating the functioning of a system of these characteristics under different meteorological conditions has been developed. The model has been applied with satisfactory results to the desalination of a NaCl solution in different experimental conditions. Data given by the mathematical simulation model was contrasted with experimental results in order to compare the reliability of the model, and good agreement was obtained. The application of this model allows the design of an electrodialysis system powered by photovoltaic energy (electrodialyzer size and the number and configuration of the PV modules), for the desalination of brackish water, as well as the study of its behaviour in different geographical locations.

Performance analysis of photovoltaic electrodialysis desalination plant at Tanote in Thar desert

The 450 peak watts photovoltaic panel coupled electrodialysis( PV-ED) plant of size 30 × 60 cms with 42 cell pairs operating at about 80 volts gives about 1000 litres per day of product water with salinity less than 1000 ppm from feed water having total dissolved solids(tds) of about 5000 ppm. The flow is fixed at 120 litres per hour for 8 hours operation per day between 8.30 a.m. to 4.30 pm.

Performance analysis of photovoltaic electrodialysis desalination plant at tanote in thar desert

Performance analysis of photovoltaic electrodialysis desalination plant at tanote in thar desert