Regenerable Sorbent System for Post Combustion CO2 Capture

TDA Research, Inc (TDA) is developing a low cost, high capacity CO₂ adsorbent and demonstrating its technical and economic viability for post-combustion CO₂ capture for existing pulverized coal-fired power plants.  TDA uses an advanced physical adsorbent to selectively remove CO₂ from the flue gas.  The sorbent exhibits a much higher affinity for CO₂ than N₂, H₂O or O₂.  The sorbent binds CO₂ more strongly than common adsorbents, providing the chemical potential needed to remove the CO₂. However, because CO₂ does not form a true covalent bond with the surface sites, the regeneration can be carried out with only a very small energy input (4.9 kcal per mol of CO₂) compared to amines (14.2 kcal/mol CO₂). We demonstrated the sorbent’s efficacy through multiple cycles for removing CO₂ from coal derived flue gas and the sorbent achieved a stable capacity.  The presence of acid gases such as SO₂ and NOx (80 and 200 ppmv, respectively) and water vapor up to 15% vol. caused no adverse effect on the CO₂ capacity.  The regeneration of the sorbent and the recovery of CO₂ and its pressurization can be achieved by several approaches, including temperature and vacuum swing.  A detailed techno-economic analysis using Aspen Plus^TM software is conducted in collaboration with University of California Irvine to estimate the impact of the TDA’s CO₂ capture system on plant efficiency and cost of electricity. Our system analysis showed that TDA’s CO₂ capture process will reduce plant efficiency only by 19.4% (compared to 31.2% reduction for amine scrubbers) while providing 90% capture and the increase in 1^st year levelized cost of electricity (COE) is 18.4% point lower than that of amines. We will present the latest results from the DOE sponsored work at the AIChE meeting.