Performance testing of zinc-bromide hybrid flow batteries for energy storage




Wasim, Rushan

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Redox flow batteries are being used for large-scale energy storage due to their charge and discharge characteristics, efficiencies of up to 75%, quick response times of 350 μs (Enomoto 2002), and minimal harmful chemical components relative to traditional acid batteries. The goal of this project is to evaluate the use of flow batteries as a backup energy storage technology. Data centers require a source of uninterruptable power in order to remain online, and redox flow batteries can fill the gap during a downtime of grid power in case of an emergency. For this project, performance testing is used to validate or invalidate the claims of the manufacturer and compare to publications of other flow batteries. The experimental testing in this study covers a high range of use cases such as VI characteristics, energy and power consumption/output of the battery, the round-trip efficiency, the charge/discharge times, and the response time of the battery. Some of the tests are more imperative to gauge how the battery acts in real-life situations. The focus of the experimental testing are the following: (i) the discharge cycle characteristics to see how the battery responds to varying loads and overloads, (ii) the energy efficiency to be able to gauge the economic feasibility of the battery, (iii) the response times so uninterrupted power supply can be optimized accordingly, and (iv) the performance of the battery with varying temperatures. The results show that the manufacturer claims hold true for the most part. The battery can perform under higher loads than it is rated for (3kW) but only up to a maximum average power of 3.92kW. The energy efficiency also decreases at high loads by 18.6%. The decrease in efficiency at the highest internal temperature of the battery is only 4.71%. Overall, the battery performed as claimed by the manufacturer, however, the greatest flaw of the battery is the monitoring system, which had errors of 14.7% at maximum loads. Fortunately, the manufacturer monitoring system is not required by the battery and the user may write their own code to acquire data.


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Mechanical Engineering