Water demand for CCS represents a series of challenges and opportunities related to water to achieve the widespread application of CO2 capture and storage technology. Maintaining the integrity of current water supplies, meeting new water demands, developing and managing new water resources, developing appropriate regulations, meeting expectations of other public and private users, and controlling costs pose many challenges. In response, opportunities arise in the form of technological advances in water treatment, use, and minimization; subsurface monitoring and modeling; capture technology development; and public education. With careful development of CCS, the challenges can be met and many of the opportunities realized.
Additional Water Resources
CCS needs water at the point of capture, with additional water resources required for the capture process, makeup water, cooling, and generation of replacement power. Evaluating the water supply as part of the CCS planning process and implementing efficient, cost-effective treatment of capture-related wastewater are critical steps to ensure that water is available for the CCS process sustainably.
Treating and Using Extracted Water
Water that may be removed from a target CO2 storage formation during CCS operations is called extracted water. Extracted water can potentially be used to manage geologic storage formation pressure and/or increase storage volume. In some situations, it may also be treatable for use in an industrial or utility process or could serve as the source of a usable product (e.g., dissolved salts and minerals that are used as road de-icer).
A number of regulations are in place to ensure water resources are actively protected and that storage activities are performing up to expectations. The monitoring, verification, and accounting programs of NETL’s Regional Carbon Sequestration Partnerships are focused primarily on the collection of data from both the near-surface and deep subsurface environments to demonstrate the safety and effectiveness of geologic storage of CO2. This affords the opportunity for industry and research personnel to develop new monitoring techniques and further improve existing techniques.
The WWG is among the many groups working to ensure that all of the challenges and opportunities related to CCS and water are recognized and addressed.
(images from Klapperich and others, 2013b)