The Water, Energy, and Carbon Sequestration Simulation Model (WECSsim) is a national dynamic simulation model that calculates and assesses capturing, transporting, and storing CO2 in deep saline formations from all coal and natural gas-fired power plants in the U.S. An overarching capability of WECSsim is to also account for simultaneous CO2 injection and water extraction within the same geological saline formation. Extracting, treating, and using these saline waters to cool the power plant is one way to develop more value from using saline formations as CO2 storage locations.
WECSsim allows for both one-to-one comparisons of a single power plant to a single saline formation along with the ability to develop a national CO2 storage supply curve and related national assessments for these formations. This report summarizes the scope, structure, and methodology of WECSsim along with a few key results. Developing WECSsim from a small scoping study to the full national-scale modeling effort took approximately 5 years. This report represents the culmination of that effort.
The key findings from the WECSsim model indicate the U.S. has several decades’ worth of storage for CO2 in saline formations when managed appropriately. Competition for subsurface storage capacity, intrastate flows of CO2 and water, and a supportive regulatory environment all play a key role as to the performance and cost profile across the range from a single power plant to all coal and natural gas-based plants’ ability to store CO2. The overall system’s cost to capture, transport, and store CO2 for the national assessment range from $74 to $208 / tonne stored ($96 to 272 / tonne avoided) for the first 25 to 50% of the 1126 power plants to between $1,585 to well beyond $2,000 / tonne stored ($2,040 to well beyond $2,000 / tonne avoided) for the remaining 75 to 100% of the plants. The latter range, while extremely large, includes all natural gas power plants in the U.S., many of which have an extremely low capacity factor and therefore relatively high system’s cost to capture and store CO2.
For context, the first gigatonne of CO2 captured from all coal and natural gas power plants has a cost of only $61 / tonne of CO2 stored and $85 / tonne avoided. These levels correspond to approximately 7,626 million gallons per day (MGD) of added water demand for the avoided emissions, and for a storage rate of 1 GtCO2 per year, this uses 5% of all capacity across the formations.
The analytical value and insight provided by WECSsim allow users to run power plant- and formation-specific scenarios to assess their cost and performance viability relative to other pairings throughout the lower 48 states of the U.S. Along with a national-level perspective, the results can identify which power plants are the most economically viable for CO2 capture, transportation, and storage (CCS), and which saline water-bearing formations are the most likely candidates to support large-scale, multi-decade CCS. A wide suite of scenarios can be developed by adjusting the cost and engineering parameter assumptions throughout WECSsim. With this capability, interested parties can address questions regarding geologic parameters, power plant make-up power, water treatment costs, and efficiencies, amongst many other salient variables both at the power plant level, and when developing a nation-wide assessment.