Energy Efficiency of Electro-Driven Brackish Water Desalination: Electrodialysis Significantly Outperforms Membrane Capacitive Deionization
Citations Over TimeTop 1% of 2020 papers
Abstract
Electro-driven technologies are viewed as a potential alternative to the current state-of-the-art technology, reverse osmosis, for the desalination of brackish waters. Capacitive deionization (CDI), based on the principle of electrosorption, has been intensively researched under the premise of being energy efficient. However, electrodialysis (ED), despite being a more mature electro-driven technology, has yet to be extensively compared to CDI in terms of energetic performance. In this study, we utilize Nernst-Planck based models for continuous flow ED and constant-current membrane capacitive deionization (MCDI) to systematically evaluate the energy consumption of the two processes. By ensuring equivalently sized ED and MCDI systems-in addition to using the same feed salinity, salt removal, water recovery, and productivity across the two technologies-energy consumption is appropriately compared. We find that ED consumes less energy (has higher energy efficiency) than MCDI for all investigated conditions. Notably, our results indicate that the performance gap between ED and MCDI is substantial for typical brackish water desalination conditions (e.g., 3 g L-1 feed salinity, 0.5 g L-1 product water, 80% water recovery, and 15 L m-2 h-1 productivity), with the energy efficiency of ED often exceeding 30% and being nearly an order of magnitude greater than MCDI. We provide further insights into the inherent limitations of each technology by comparing their respective components of energy consumption, and explain why MCDI is unable to attain the performance of ED, even with ideal and optimized operation.
Related Papers
- → Comparison of Ion Selectivity in Electrodialysis and Capacitive Deionization(2022)56 cited
- → Stability of Ion Exchange Membranes in Electrodialysis(2022)26 cited
- → Corrugated graphene layers for sea water desalination using capacitive deionization(2017)41 cited
- → Concentration Polarisation in the Electrodialysis Process and the Polarisation Characteristics of Ion-selective Membranes(1988)18 cited
- → Performance of Membrane Capacitive Deionization Process Using Polyvinylidene Fluoride Heterogeneous Ion Exchange Membranes Part II : Performance Study of Membrane Capacitive Deionization Process(2017)