CO2 Capture with Ionic Liquids Involving Phase Change (Final Report)
- Univ. of Notre Dame, IN (United States)
Coal-fired power plants provide nearly 50% of all electricity in the U.S. While coal is a cheap and abundant natural resource, its continued use contributes to rising carbon dioxide (CO2) levels in the atmosphere. Capturing and storing this CO2 would reduce atmospheric greenhouse gas levels while allowing power plants to continue using inexpensive coal. Carbon capture and storage represents a significant cost to power plants that must retrofit their existing facilities to accommodate new technologies. Reducing these costs is the primary objective of ARPA-E's carbon capture program. Researchers at the University of Notre Dame and their partners at Matric developed a new CO2 capture process that uses materials that we call Phase Change Ionic Liquids (PCILs). PCILs are solid at the temperature of the CO2 absorption but change to liquid when they bind with CO2. The PCILs have a high capacity for CO2 at post-combustion flue gas pressures and temperatures because of a chemical reaction between the CO2 and the PCIL. Upon heating, the CO2 is released, and the PCILs re-solidify. The heat released in the solidification process reduces the amount of external heat that must be added. As with conventional CO2 capture processes, the PCIL process has an absorber and a regenerator. Computer simulation of the process enabled calculation of viable process conditions and power needs. The main concepts of the process were demonstrated using lab-scale apparatus. Capture of CO2 was carried out using a sieve tray column in continuous mode. Desorption of the CO2 in the regenerator occurred while the liquid droplets solidified. The key to making this process viable was the use of a mixture of the complexed liquid with the unreacted solid particles in the absorber. This mixture formed a well-behaved slurry that flowed readily. Therefore, handling of solid particles is avoided in the process. Parasitic power was decreased by 55% from the amount required by the monoethanolamine (MEA) process. For the PCIL process, parasitic power is only 23% of the net power generated by the plant, which is remarkably close to the 19% DOE target. The capital cost for the CO2 capture unit is higher for the PCIL process than the MEA process. Nonetheless, the overall increase in the cost of electricity (COE) is dramatically lower - only 4.1¢/kWh for the PCIL process compared with 5.7¢/kWh for the MEA process. The cost of CO2 avoided is $48/ton of CO2. As a result, we conclude that CO2 capture with phase change ionic liquids is an exceedingly promising technology.
- Research Organization:
- University of Notre Dame, IN (United States)
- Sponsoring Organization:
- USDOE Advanced Research Projects Agency - Energy (ARPA-E)
- DOE Contract Number:
- AR0000094
- OSTI ID:
- 1507392
- Report Number(s):
- DOE-ND-1111-2
- Country of Publication:
- United States
- Language:
- English
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