TDA Research (TDA), along with its partners, will continue to advance development of their novel sorbent-based pre-combustion carbon capture technology through pilot-scale testing. TDA’s high-temperature pressure swing adsorption (PSA)-based process uses an advanced physical adsorbent that selectively removes CO2 from coal-derived syngas at temperatures as high as 300 degrees Celsius, achieving high power-cycle efficiency. The sorbent is a mesoporous carbon grafted with surface functional groups that remove CO2 via physical adsorption. The sorbent binds CO2 more strongly than common physical adsorbents, providing the chemical potential needed for the high temperature operation. As CO2 does not form a true covalent bond with the surface sites (as with chemical absorbents), the sorbent regeneration can be accomplished with a relatively small energy input.
Previous work conducted under DOE/NETL funding (DE-FE0000469) verified the techno-economic viability of the technology through bench-scale and slipstream testing. The sorbent was shown to achieve a very high working capacity, maintain its performance over 11,650 cycles, and withstand the potential impurities in actual syngas. Researchers found that the high-temperature CO2 removal capability and low regeneration energy requirement resulted in the plant efficiency of the TDA CO2 capture process exceeding 34 percent higher heating value (HHV), compared to 31.4 percent for the conventional SelexolTM solvent system. The capital cost for an IGCC system with TDA’s process was estimated to be 12 percent lower than that of IGCC with the Selexol process. For the current project, the sorbent performance will be evaluated using actual syngas in a fully equipped system at a larger scale and for a longer duration. Researchers will optimize the sorbent reactor design using computational fluid dynamics (CFD). The PSA cycle sequence will be improved through adsorption modeling. Two 0.1 megawatt electric (MWe) tests will be conducted for 9 to 12 months in a fully equipped prototype unit and using actual syngas to prove the viability of the new technology. All results will feed into a techno-economic analysis supported with Aspen Plus® simulations to calculate the impact of the CO2 capture system on plant efficiency and the cost of electricity.
The first pilot test will be conducted at the Power Systems Demonstration Facility at the National Carbon Capture Center (NCCC) and the second test at Sinopec’s IGCC plant in China. These facilities use different types of gasifiers (air-blown transport gasifier vs. oxygen-blown gasifier) and feedstocks (low rank
coals vs. petcoke), which will allow researchers to assess process efficacy in very different gas streams.
The mission of the U.S. Department of Energy Office of Fossil Energy’s (DOE FE) Carbon
Capture Research & Development (R&D) Program, implemented through the National
Energy Technology Laboratory (NETL), is to develop innovative carbon dioxide (CO2)
emissions control technologies for fossil fuel-based power plants. The Carbon Capture
R&D Program portfolio of pre- and post-combustion CO2 emissions control technologies
and related CO2 compression is focused on advancing technological options for new
and existing power plants to enable cost-effective CO2 capture for beneficial use or
storage of CO2 and ensure that the United States will continue to have access to safe,
reliable, and affordable energy from fossil fuels. The DOE FE/NETL goal is to demonstrate
second-generation technologies that can capture 90 percent of the CO2 at less than $40
per metric ton (tonne) in the 2020-2025 timeframe. DOE is also committed to extend
R&D support to even more advanced transformational carbon capture technologies
that will increase competitiveness of fossil-based energy systems beyond 2035.
Pre-combustion CO2 capture technologies are applicable to integrated gasification
combined cycle (IGCC) power plants, where solid fuel is converted into gaseous
components (synthesis gas or syngas) by applying heat under pressure in the presence
of steam and oxygen. The carbon is captured from the syngas before combustion and
power production occurs. Pre-combustion carbon separation and capture is relatively
simple and less expensive compared to post-combustion capture as it has a greater
driving force, with the processed syngas at a much lower volume, at a higher pressure,
and containing a higher concentration of CO2. Pilot-scale testing with actual coal-derived
syngas is a key step in the continued development of promising sorbent-based precombustion
CO2 capture technologies.
TDA’s high temperature PSA-based CO2 removal technology holds potential to significantly improve the IGCC process efficiency needed for economically viable production of power from coal and other heavy feedstocks. Higher net plant efficiency and lower capital and operating costs result in a substantial reduction in the cost of electricity for the IGCC plant. Continued development and validation of the process will put it on a path to be ready for first-of-a-kind commercial-size demonstration by 2025.
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