Companies that develop systems to recover carbon dioxide from power plants are looking for cost-effective solutions to limit emissions. SRI is examining several approaches, including carbon dioxide capture from an advanced integrated gasification combined-cycle (IGCC) process. This particular technology has technical and economic advantages as compared with conventional coal-combustion systems. The IGCC process is an efficient and environmentally friendly way to produce electricity from coal.
SRI is investigating use of an aqueous ammonium carbonate solution to capture carbon dioxide and hydrogen sulfide from the gas stream of hydrogen, carbon dioxide, and other gases produced in a coal gasifier. The spent solution is heated to about 160°C to liberate carbon dioxide and hydrogen sulfide at high pressures of 40 bar, which meets the power requirement to compress the gas to the pipeline pressure of 150 bar. The regenerated solution is cooled and cycled back for absorption. The relatively pure hydrogen obtained in the process is used for conversion into electricity using gas turbines or fuel cells—without generating additional carbon dioxide. The hydrogen can also be used to make chemicals such as methanol and ammonia.
This process, called AC-ABC for ammonium carbonate-ammonium bicarbonate, has been proved in bench-scale testing and will be tested at an operating gasifier site in the future. SRI has shown that the solution has a high capacity for carbon dioxide and hydrogen sulfide, which reduces solvent requirements. The carbon dioxide can be released at high pressures, and the regenerated solution does not degrade at the high temperature.
In addition, initial results indicate that the cost of electricity for the ammonium carbonate-based capture system is significantly less than that for one that uses the solvent Selexol™. Approaches such as the IGCC process can be integrated into future plant designs to improve cost effectiveness and address environmental concerns.
This material is based upon work supported by the Department of Energy under award number DE-FE000-896.
