Preprint / Version 1

Techno-economic analysis of a combined power plant CO2 capture and direct air capture concept for flexible power plant operation


  • Moataz Sheha
  • Edward Graham Massachussetts Institute of Technology
  • Emre Gencer
  • Dharik Mallapragada
  • Howard Herzog
  • Phillip Cross
  • James Custer
  • Adam Goff
  • Ian Cormier



The electric power sector must be deeply decarbonized at a reasonable cost to achieve sustainability through electrification of other sectors. While variable renewable energy generation is expected to dominate grid decarbonization efforts, variability creates the need for supply- and demand-side technologies that can operate flexibly to balance the system. This paper proposes a new concept for power plant flue gas capture integrated with a novel lime-based direct air capture technology to enable flexible operation of the power plant and achieve negative emissions under all operating scenarios. Steady-state models are developed, and sensitivity analyses are conducted on key process variables to investigate system performance. The results, presented at three different power plant loading levels (100%, 40%, and 0%), demonstrate negative emissions of -0.188 tCO2/MWh at 100% loading and -2.087 tCO2/MWh at 40% loading. Economic modeling suggests the need for carbon credits exceeding $170/tCO2 to achieve positive net present values.


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