Parametric analysis of technology costs for CO2 storage in saline formations

Abstract Over the last decade, a substantial amount of economic, engineering, and geoscience research has focused on storing CO 2 in geological formations. Of those different formations, storage in saline water-bearing formations represents the largest storage potential. Fossil fuel-based power plants in the U.S. (coal and natural gas) contributed to 40% of all CO 2 emissions in 2008 and therefore represent an important factor to address atmospheric CO 2 emissions. The Water, Energy and Carbon Sequestration Simulation Model (WECSsim) was developed to calculate water use and treatment options, CO 2 injection volumes and the levelized cost of energy (LCOE) results for both a single representative power plant paired with a saline formation scenario, and a full power plant fleet . The details of the analysis presented here broadly demonstrate the sensitivity of CO 2 capture and storage (CCS) costs in geologic saline formations with water extraction, treatment and reuse to changes in the water demands associated with implementing CCS across the power plant fleet (coal and natural gas). The majority of the coal and natural gas plants in the U.S. have an avoided cost of $70–200 per tonne of CO 2 . Storing 1.0 Gt/yr of the nation’s 2.3 Gt/yr total CO 2 emissions returns an avoided (storage) cost of range 79–143 (57–81) $/t ($US 2013) under various scenarios. These scenarios include allowing competition between power plants for saline formation space to store CO 2 , varying the duration of the storage rights, and permitting the extraction of saline waters for treatment. Under the same 1 Gt/yr captured scenario, the extracted and treated water volumes could offset 12% of the added water demand due to the parasitic energy requirements of CCS at the national level. The cost of water treatment, using a reverse osmosis system, ranges between approximately $3.20/m 3 water (for larger, older coal-fired plants like the San Juan Power Generating Station) and $2.60/m 3 water for natural gas combined cycle plants (such as the Oyster Creek Power Generating Station) with substantial variability in costs based on plant location and design. For context, the levelized cost of energy (LCOE) composition of the pulverized coal-based San Juan Generation Station is 52%, 43% and 5% for the base LCOE, parasitic energy requirements, and water extraction, treatment and utilization costs, respectively. Similarly, for the Oyster Creek natural gas combined cycle plant, these percentages are 64%, 33%, and 2% of the total LCOE, respectively. In both technology cases the parasitic energy requirement costs far outweigh the cost to extract, treat, transport, and utilize saline formation waters. Additional results indicate that of the 325 saline formations included in the national-level analysis, the Mt. Simon formation has an estimated capacity to hold 53% of all the CO 2 generated from the U.S. coal and natural gas-based power plants without extracting and treating saline water. The St. Peter Sandstone formation could hold 43%, though with saline water extraction and treatment. These results suggest that focusing research, development and demonstration (RD&D) efforts on careful geologic site selection and reducing the parasitic energy penalty, and its respective costs, will help lower the overall cost of CCS across the U.S. coal and natural gas-based power plant fleet.