The combustion of fossil fuels in nearly pure oxygen—known as oxy-combustion—is a promising technology for capturing carbon dioxide (CO2) from fossil fuel power plants, and reducing greenhouse gas emissions. However, the cost, energy consumption, and operational challenges of oxygen separation are significant challenges that NETL researchers are helping to tackle.

In an oxy-combustion process, a pure or enriched oxygen (O2) stream is used instead of air for combustion. In this process, almost all of the nitrogen (N2) is removed from the air, yielding a stream that is approximately 95 percent O2. As a result, the volume of flue gas made up of CO2 is approximately 75 percent less than from commonly used air-fired combustion processes. The process also allows easier removal of pollutants like SOx, NOx, mercury, and particulates from the flue gas.

Oxy-combustion power production involves three major components: oxygen production (air separation unit [ASU]), the oxy-combustion boiler (fuel conversion [combustion] unit), and CO2 purification and compression. And, the oxy-combustion systems can be configured in either low- or high-temperature boiler designs.

Because the cost of evolving oxy-combustion technologies is too high, NETL is developing advanced technologies to reduce the costs associated with current systems. R&D efforts are focused on developing pressurized oxy-combustion power generation systems, as well as membrane-based oxygen separation technologies. Much of NETL’s effort is being done in collaboration with industry and academia, including two projects at pilot scale, and one at bench scale.