The CO2-PENS Water Treatment Model: Evaluation of Cost Profiles and Importance Scenarios for Brackish Water Extracted During Carbon Storage

Extraction of in-situ water is one of the options for minimizing the impact of large-scale CO 2 injection in saline aquifers or during enhanced oil recovery (EOR). The amount of water to be produced could be significant depending on in-situ conditions and injection parameters. Evaluating the costs of treatment is complex, as the quality of the water may vary considerably from treatments based on well-known seawater chemistry, including reverse osmosis. We evaluated a brackish-salinity water to be extracted from a future CO 2 injection and storage location in eastern China for prototype treatment costs for both cooling water and boiler water final treatment goals. Costs for treatment of the water, excluding costs for organic pretreatment, were within the range of previously analyzed costs for higher-salinity waters (US$1.53-6.20) but are likely to be lower when economies of scale are included for a full-scale, higher volume treatment facility. Importance analysis lends insight into process factors that may not contribute the highest unit costs to treatment but on whole are very important to total system costs. We found that the acid rate for pretreatment, zero-liquid discharge disposal, feed water temperature, and water transportation costs, were the most important factors within total system costs for this analysis.