Desalination of unconventional water sources such as brackish aquifers, which has been historically cost prohibitive, is an increasingly attractive means providing sustainable water resources in water stressed regions. Capacitive deionization (CDI), which electrochemically desalinates via electric double-layer ion storage, is a potentially energy efficient alternative to reverse osmosis (RO). Previous studies have focused on improving CDI performance through the introduction of ion exchange membranes, surface functionalization of carbon electrodes, or faradaic ion insertion materials. While these techniques have successfully reduced energy consumption or increased ion adsorption capacity in CDI systems, additional clarity is necessary to evaluate the associated performance and cost tradeoffs across the design space. In this study, an equivalent circuit (M)CDI model was used to measure the sensitivity of CDI performance to operational and material changes. A simplified, operational model for both capacitive and faradic materials in CDI was used to conduct a techno-economic analysis (TEA) of proposed improvement to CDI. The results of the sensitivity analysis and TEA were used to evaluate the current cost-effectiveness of CDI technologies as well as near-term projections for changes in component costs. Additionally, targets are set for performance and material properties, such as lifetimes, necessary to favorably compete with RO.

Establishing cost and performance goals for electrochemical deionization: A techno-economic analysis of faradaic and capacitive materials in CDI systems

255th National Meeting (2018)

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