Energy Efficiency of Electro-Driven Brackish Water Desalination: Electrodialysis Significantly Outperforms Membrane Capacitive Deionization
| Autor: | Sohum K. Patel, Menachem Elimelech, Mohan Qin, W. Shane Walker |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Salinity
Brackish water Capacitive deionization Environmental engineering Portable water purification General Chemistry Energy consumption 010501 environmental sciences Electrodialysis 01 natural sciences Desalination Water Purification Environmental Chemistry Environmental science Adsorption Reverse osmosis Electrodes Saline Waters 0105 earth and related environmental sciences Efficient energy use |
| Zdroj: | Environmental Science & Technology. 54:3663-3677 |
| ISSN: | 1520-5851 0013-936X |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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