Pathway To Low-Carbon Lignite Utilization; U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Cooperative Agreement No. DE-FE0024233
Utilities continue to investigate ways to decrease their carbon footprint. Carbon capture and storage (CCS) can enable existing power generation facilities to maintain operations and address carbon reduction. Subtask 2.1 – Pathway to Low-Carbon Lignite Utilization focused on several research areas in an effort to find ways to decrease the cost of capture across both precombustion and postcombustion platforms. Two postcombustion capture solvents were tested, one from CO 2 Solutions Inc. and one from ARCTECH, Inc. The CO 2 Solutions solvent had been evaluated previously, and the company had incorporated the concept of a rotating packed bed (RPB) to replace the traditional packed columns typically used. In the limited testing performed at the Energy & Environmental Research Center (EERC), no CO 2 reduction benefit was seen from the RPB; however, if the technology could be scaled up, it may introduce some savings in capital expense and overall system footprint. Rudimentary tests were conducted with the ARCTECH solvent to evaluate if it could be utilized in a spray tower configuration contactor and capture CO 2 , SO 2 , and NO x . This solvent after loading can be processed to make an additional product to filter wastewater, providing a second-tier usable product. Modeling of the RPB process for scaling to a 550-MW power system was also conducted. The reduced cost of RPB systems combined with a smaller footprint highlight the potential for reducing the cost of capturing CO 2 ; however, more extensive testing is needed to truly evaluate their potential for use at full scale. Hydrogen separation membranes from Commonwealth Scientific and Industrial Research Organisation (CSIRO) were evaluated through precombustion testing. These had also been previously tested and were improved by CSIRO for this test campaign. They are composed of vanadium alloy, which is less expensive than the palladium alloys that are typically used. Their performance was good, and they may be good candidates for medium-pressure gasifiers, but much more scale-up work is needed. Next-generation power cycles are currently being developed and show promise for high efficiency, and the utilization of supercritical CO 2 to drive a turbine could significantly increase cycle efficiency over traditional steam cycles. The EERC evaluated pressurized oxy-combustion technology from the standpoint of CO 2 purification. If impurities can be removed, the costs for CO 2 capture can be lowered significantly over postcombustion capture systems. Impurity removal consisted of a simple water scrubber referred to as the DeSNO x process. The process worked well, but corrosion management is crucial to its success. A model of this process was constructed. Finally, an integrated gasification combined-cycle (IGCC) system model, developed by the Massachusetts Institute of Technology (MIT), was modified to allow for the modeling of membrane systems in the IGCC process. This modified model was used to provide an assessment of the costs of membrane use at full scale. An economic estimation indicated a 14% reduction in cost for CO 2 separation over the SELEXOL™ process. This subtask was funded through the EERC–DOE Joint Program on Research and Development for Fossil Energy-Related Resources Cooperative Agreement No. DE-FE0024233. Nonfederal sponsors for this project were the North Dakota Industrial Commission, Basin Electric Power Cooperative, and Allete, Inc. (including BNI Coal and Minnesota Power).