Combining power plant water needs and carbon dioxide storage using saline formations: Implications for carbon dioxide and water management policies

Research 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 (CO2) in geological formations is one of many proposed methods to manage, and likely reduce, CO2 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 CO2 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 injection-induced changes in subsurface groundwater chemistry and fate and transport of supercritical CO2. Initial water–CO2-formation reactions include dissolution of carbonate minerals as expected, and suggest that very little CO2 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™) shows promise for economical desalination at the volumes of recovered water under consideration. Results indicate a coupled use CO2 storage and water extraction and treatment system may be feasible for tens to hundreds of years.