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Scientists in Canada have combined photovoltaic power generation with capacitive deionization (CDI)-based water purification, which is claimed to have low operating cost, higher energy efficiency and less water rejection than conventional purification techniques. conventional.
Researchers at Canadas École de technologie supérieure (ÉTS) have developed a photovoltaic water purification technology based on capacitive deionization (CDI), a technique increasingly used to remove ionic and polarizable species from water and often used for desalination. water with a low or moderate salt concentration.
The technology is also claimed to have low operating cost, higher energy efficiency and lower water rejection compared to conventional purification techniques.
“Our new technology does not require a storage medium between the photovoltaic panel and the CDI desalination cell,” Alaa Ghamrawi, corresponding author of the research, explained to pv magazine . “It is based on a specific algorithm for the application of photovoltaic energy to the desalination process, as well as a new MPPT technology based on flow adjustment and not on the conversion of electrical energy.”
The system prototype uses a photovoltaic panel equipped with a diode and a shunt resistor. The panel is DC connected to a membrane capacitive deionization (MCDI) cell that creates a short circuit or reverse voltage across the electrodes when the maximum ion concentration is reached during adsorption.
The MCDI cell also uses the flow rate as a control parameter. “The variation of the flow rate will be an essential factor to adapt the impedance of the MCDI cell and, ultimately, the load applied on the photovoltaic panel,” the scientists explained, noting that they were able to control this flow rate to optimize the power produced by the solar module through a new algorithm, which they called Maximum Saline Adsorption Tracking (MSAT, for its acronym in English).
After testing the prototype under various operating conditions, the researchers found that the MCDI photovoltaic cell was capable of producing 28 liters of desalinated water on a sunny summer day, compared to 24 liters for a conventional MCDI unit. They also verified that the tracking efficiency of the MSAT is 98.6%, comparable, according to them, to that of the conventional MPPT.
“Conventional MCDI cells require more expensive MPPT controllers to achieve high performance,” Ghamrawi explained, referring to the economic advantages of a direct DC connection. “The battery cost of each CDI cell is about $200 for a 200AH device. Then theres the cost of the controller, which is around $10, and the MPPT microcontroller is over $20.”
The proposed system is described in the article “ Maximum salt adsorption tracking in capacitive deionization cell powered by photovoltaic solar panel”, published in Desalination . “At the moment, we have started the commercial design by developing the electronic board and the system components,” explains Ghamrawi. |
