Advanced combustion power generation combusts coal in an oxygen-rich environment rather than air. This eliminates most of the nitrogen found in air from the combustion process, resulting in flue gas composed largely of carbon dioxide (CO2) and water, as well as contaminants from the fuel (including coal ash). The high concentration of CO2 and absence of nitrogen simplify separation of CO2 from the flue gas for storage or beneficial use. Thus, oxygen-fired combustion is an alternative approach for carbon capture and storage (CCS) for coal-fired systems. However, the appeal of oxygen-fired combustion is tempered by several challenges, namely the capital cost, energy consumption, and operational challenges of supplying oxygen to the combustion system, air infiltration that dilutes the flue gas with nitrogen, and purification processes to remove pollutants and excess oxygen from the concentrated CO2 stream. Consequently, advanced combustion research and development (R&D) is exploring technologies that can lower the cost of oxygen supplied to the system and/or increase the overall system efficiency. Cost-shared R&D is being performed both externally, by industry, research organizations, and academic institutions, and internally, through the National Energy Technology Laboratory’s (NETL) Research and Innovation Center (RIC), to develop oxy-combustion and chemical looping combustion (CLC) technologies to overcome these challenges.
The combustion of fossil fuels in nearly pure oxygen, rather than air, presents an opportunity to simplify CO2 capture in power plant applications.
CLC is oxy-fuel combustion without the need to separate oxygen from air prior to combustion, reducing energy demand and system costs while capturing CO2.