a b s t r a c tResearch involving management of carbon dioxide has increased markedly over the last decade as it relates to concerns over climate change. Capturing and storing carbon dioxide (CO 2 ) in geological formations is one of many proposed methods to manage, and likely reduce, CO 2 emissions from burning fossil fuels in the electricity sector. Saline formations represent a vast storage resource, and the waters they contain could be managed for beneficial use. To address this issue, a methodology was developed to test the feasibility of linking coal-fired power plants, deep saline formations for CO 2 storage, and extracting and treating saline waters for use as power plant cooling water.An illustrative hypothetical case study examines a representative power plant and saline formation in the south-western United States. A regional assessment methodology includes analysis of injectioninduced changes in subsurface groundwater chemistry and fate and transport of supercritical CO 2 . Initial water-CO 2 -formation reactions include dissolution of carbonate minerals as expected, and suggest that very little CO 2 will be stored in mineral form within the first few centuries. Reservoir simulations provide direct input into a systems-level economic model, and demonstrate how water extraction can help manage injection-induced overpressure. Options for treatment of extracted water vary depending upon site specific chemistry. A high efficiency reverse osmosis system (HERO TM ) shows promise for economical desalination at the volumes of recovered water under consideration. Results indicate a coupled use CO 2 storage and water extraction and treatment system may be feasible for tens to hundreds of years.

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Electrodialysis (ED) desalination performance of different conventional and laboratory-scale ion exchange membranes (IEMs) has been evaluated by many researchers, but most of these studies used their own sets of experimental parameters such as feed solution compositions and concentrations, superficial velocities of the process streams (diluate, concentrate, and electrode rinse), applied electrical voltages, and types of IEMs. Thus, direct comparison of ED desalination performance of different IEMs is virtually impossible. While the use of different conventional IEMs in ED has been reported, the use of bioinspired ion exchange membrane has not been reported yet. The goal of this study was to evaluate the ED desalination performance differences between novel laboratory‑scale bioinspired IEM and conventional IEMs by determining (i) limiting current density, (ii) current density, (iii) current efficiency, (iv) salinity reduction in diluate stream, (v) normalized specific energy consumption, and (vi) water flux by osmosis as a function of (a) initial concentration of NaCl feed solution (diluate and concentrate streams), (b) superficial velocity of feed solution, and (c) applied stack voltage per cell-pair of membranes. A laboratory‑scale single stage batch-recycle electrodialysis experimental apparatus was assembled with five cell‑pairs of IEMs with an active cross-sectional area of 7.84 cm2. In this study, seven combinations of IEMs (commercial and laboratory-made) were compared: (i) Neosepta AMX/CMX, (ii) PCA PCSA/PCSK, (iii) Fujifilm Type 1 AEM/CEM, (iv) SUEZ AR204SZRA/CR67HMR, (v) Ralex AMH-PES/CMH-PES, (vi) Neosepta AMX/Bare Polycarbonate membrane (Polycarb), and (vii) Neosepta AMX/Sandia novel bioinspired cation exchange membrane (SandiaCEM). ED desalination performance with the Sandia novel bioinspired cation exchange membrane (SandiaCEM) was found to be competitive with commercial Neosepta CMX cation exchange membrane.

Zero Discharge Desalination (ZDD) is a very-high-recovery hybrid desalination system, typically comprised of a primary desalter (such as reverse osmosis (RO) or nanofiltration (NF)) and electrodialysis metathesis (EDM). The EDM acts as a “kidney” by removing troublesome salts from the concentrate of the primary desalter, which allows for additional recovery of potable water. A mathematical model was developed to simulate ZDD system performance using mass balance, desalination design equations, and experimental data. Model results confirm that ZDD can achieve >97% system recovery for brackish water with (a) a feed total dissolved solids (TDS) concentration of <3 g/L; (b) relatively high fractions of multivalent ions (e.g., calcium and sulfate mass concentrations of >60% of the TDS); and (c) a silica content of <40 mg/L. Furthermore, model results indicate that the required ZDD specific energy consumption (a) increases by 0.77 kWh per 1 g/L of feed TDS; (b) increases with lower permeate TDS, especially below 500 mg/L; and (c) generally decreases with higher recovery on the primary desalter (e.g., RO or NF). ZDD system recovery generally decreases by ∼1% per 1 g/L of feed TDS. Higher TDS feedwater (e.g., 3.5 to 5 g/L) limits ZDD system recoveries to 94% to 90%, respectively.

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