Companies that build or operate coal-fired power plants are looking for cost-effective solutions to recover carbon dioxide (CO2). Integrated gasification combined-cycle (IGCC) technology is emerging as an efficient, environmentally friendly way to produce electricity from coal. While IGCC accounts for a small fraction of current generating capacity, SRI is already developing a solvent-based approach to capture the CO2.
SRI’s technology uses an aqueous ammoniated solution containing ammonium carbonate (AC) to simultaneously capture CO2 and hydrogen sulfide (H2S) from synthesis gas, a gas mixture that also contains hydrogen. The spent solution is heated to liberate carbon dioxide and hydrogen sulfide at high pressures (20-50 bar), which means that only a 3 to 7.5 pressure ratio is required to compress the carbon dioxide to pipeline pressure (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 at SRI and will undergo slipstream testing from an air-blown gasifier at a field site. 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-FE0000896. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.