Washington, D.C. - Two new patented sorbents used for carbon dioxide (CO2) capture from coal-based power plants have moved closer to commercialization as a result of a licensing agreement between the Office of Fossil Energy's (FE) National Energy Technology Laboratory (NETL) and ADA Environmental Solutions (ADA-ES).
The nonexclusive agreement facilitates negotiations on intellectual property rights, protects proprietary information, and grants non-exclusive licensing of the new technology. Under federal regulations, NETL is authorized to obtain, maintain, and own patent protection for its inventions, including those funded through collaborative agreements. By granting a commercial license for these sorbents, NETL can now convey and control the right to make, use, and sell the products and services claimed in the patent, thereby assuring strategic commercialization throughout the coal-fired power plant industry.
CO2 capture is an important component of carbon capture and storage (CCS) technology, viewed by many experts as an integral part of a portfolio strategy (including increased use of renewable and nuclear energy, and greater efficiencies) for confronting increasing atmospheric carbon dioxide emissions and potential climate change. Coal-based power and industrial plants are essential to U.S. energy production and are projected in many forecasts to remain so for the foreseeable future. But they are also among the most carbon-intensive energy sources.
FE’s comprehensive CCS research includes developing new materials that can capture and release CO2 at reasonable energy and operating costs. Traditional solvent-based systems consume too much energy, either in operation or during regeneration of the solvents. So FE is developing and testing a wide range of approaches.
A promising solution for affordable CO2 capture is "dry scrubbing" or chemical absorption of CO2 using a solid regenerable sorbent. The most important advantage of solid sorbents is the potential to significantly reduce the amount of energy required to capture and release CO2. These range from alkaline earth metal oxides or hydroxides that can absorb CO2 at temperatures that typically range from about 100—300 °C to impregnating a porous substrate with one of the liquid solvents. In all of these, the sorbent can be regenerated in a subsequent step, after the CO2 is removed. The efficiencies of these processes are highly dependent on the optimum temperature and pressure conditions at which absorption and regeneration are performed. In the case of high-performance sorbents, both of these mechanistic steps occur with the lowest possible energetic and operational costs.
In collaboration with ADA-ES and the Electric Power Research Institute (EPRI), NETL in 2008 began testing candidates for solid-sorbent CO2 capture in coal-fired power plants. The initial research included a cost analysis and sorbent screenings at both laboratory and pilot scales. Based on the success of the initial phase, the research project moved to the technology development and pilot-scale demonstration in 2010. The goals of this phase were to demonstrate a ninety percent CO2 capture rate at a projected long-term cost that would add less than a 35 percent increase to the cost of producing electricity.
The research resulted in two patents issued to NETL; specifically, U.S. Patent No. 6,547,854, titled Amine Enriched Sorbents for Carbon Dioxide Capture, and U.S. Patent No. 7,288,136, titled High Capacity Immobilized Amine Sorbents. Both patents represent new methods for making low-cost CO2 sorbents that can be used in large-scale gas-solid processes. The first entails treating a solid substrate with acid or base and a substituted amine salt, eliminating the need for organic solvents and polymeric materials for the preparation of CO2 capture systems. The second patent entails treating an amine to increase the number of secondary amine groups and impregnating the amine in a porous solid support. The method increases the CO2 capture capacity and decreases the cost of utilizing an amine-enriched solid sorbent in CO2 capture systems.
Under a multi-year study examining ways to retrofit existing coal fired power plants with carbon capture technology, NETL and its partners (ADA-ES, the Electric Power Research Institute, and Southern Company) will continue to demonstrate the sorbents in a 1 megawatt (about 24 tons CO2/day) pilot-scale plant and conduct detailed engineering analysis to provide technology cost estimates for post-combustion capture. In the demonstration, solid sorbents are used to separate CO2 from flue gas. Once the sorbents are saturated, they are processed to isolate purified CO2 for reuse or sequestration. The same process also regenerates the sorbents. With initial reports showing a greater than ninety percent capture rate for the patented solid sorbents, further refinements to the technologies and processes surrounding this research offer great promise.