ADA's Solid Sorbent CO2 Capture process: Developing Solid Sorbent Technology to Provide the Necessary Flexible CO2 Capture Solutions for a Wide Range of Applications

Abstract Thermal power plant efficiency upgrades and fuel switching from coal to natural gas will not be sufficient for meeting societal needs for decarbonization of the world's electric generating fleet. While coal remains an abundant and more cost effective fuel worldwide than natural gas, recent gas production in North America has driven a significant movement towards fuel switching from coal to gas. However, fuel switching alone will not be a p ractical method for necessary CO 2 emissions reductions. As a result, CO 2 capture technologies need to be developed which are scalable from process heaters and small gas plants to 1,000 MWe coal generating units. Retrofit technologies will also be needed because it will take decades to overhaul the entire electric generating infrastructure. Post-combustion CO 2 capture will be needed to facilitate progressive CO 2 emissions reductions from existing infrastructure as well as being able to flexibly adapt to any new fossil flue gas stream to provide the necessary CO 2 emissions reductions for future regulatory compliance. Carbon mitigation regulations are being discussed in several countries. The United States’ Environmental Protection Agency (US EPA) proposed a new rule, “Standards of Performance for Greenhouse Gas Emissions from New Stationary Sources: Electric Utility Generating Units” in April 2013 for new construction of power plants in the United States, which indicated an emissions limit of 1,100 lbs/MWhr for coal fired power plants. Natural gas combined cycle plants do not require CO 2 capture technology for the current EPA proposal. For coal fired power plants, this emissions rate does not require 90% or more CO 2 capture, and instead only calls for∼40-50% CO 2 capture from a unit depending upon the specific steam cycle and fuel utilized. As a result, high capital cost technologies such as oxy-fuel combustion and integrated gasification combined cycle (IGCC) with pre- combustion CO 2 capture for coal fueled applications may not be economically advantageous under this proposed regulation. However, an advantage of post-combustion capture, unlike integrated gasification combined cycle or oxy-fuel retrofit, is that it may be implemented as a trim over a broad range of CO 2 capture from ∼5-90% to meet potential regulatory requirements and industry needs with a potentially significantly lower capital expense necessary for compliance. In addition, post-combustion CO 2 capture technology may be adapted to gas fired applications in the future indicating its value as a developmental technology in a time of regulatory uncertainty. In order to explore the costs and technical challenges associated with providing large scale CO 2 capture at coal fired power plants over a wide range of potential capture requirements, ADA has developed a 500 MWe conceptual design for a post-combustion CO 2 capture unit that utilizes solid sorbents. ADA has also recently completed construction of a first-in-the-world, 1 MWe scale, CO 2 capture pilot facility that utilizes dry solid sorbents and fluidized bed technology to efficiently capture CO 2 from power plant flue gas without the energy penalties associated with heating and evaporating water-based liquid amine solvents. This facility will commence operation in 2014 and be used to validate models and assumptions used to scale solid-sorbent CO 2 capture technology to necessary levels for industrial compliance. In addition, the design and construction exercise of the 1 MWe pilot plant has aided in performing cost estimates that may be compared to liquid amine-based post-combustion capture systems using methodology based upon the U.S. Department of Energy's National Energy Technology Laboratory's Carbon Capture reports of Cases 10 and 12. ADA has also compared the energy penalties and potential impacts to the levelized costs of electricity associated with a range of partial capture scenarios to assess the relative costs of partial capture compared with 90% CO 2 capture. This study shows how solid-sorbent post-combustion capture technology can provide advantages over aqueous amine technology as well as providing flexible solutions to CO 2 capture needs at a wide range of scales and in an environment of regulatory uncertainty.