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The primary project objective was to synthesize a retrofit design of a natural gas combined cycle plant (F-series gas turbines in 2x1 configuration) to integrate post-combustion (PCC) and direct air carbon capture (DAC) systems that could produce power with negative emissions across a wide range of loads. The IP-LP crossover and LP steam system of the NGCC were reconfigured to enable 97% CO2 capture in the PCC system at all loads, and heat integration with the DAC reduced the parasitic load of carbon capture by recovering the heat of condensation of the steam. Similar results were found for H-series gas turbines. A second objective was to assess whether the plant would be dispatched on a grid that had heavy penetration of renewable power. The dispatch of this integrated plant was optimized across different electricity price signals and carbon prices to calculate a net present value assuming a capital return factor of 0.12 and a depreciation schedule of 20 years. The NPV was positive at carbon prices that exceed $225/tonne with the assumed price signals. The retrofit plant was dispatched 39% of the time compared to the base case B31A plant 33% of the time at carbon prices of $150/tonne. The Levelized cost of electricity results show that a CO2 price of $162/tonne CO2 is necessary for the retrofit to obtain a $75/MWh LCOE value. The DAC fiber sorbent system is comprised of low-cost cellulose acetate, silica particles and polyethylene imine sorbent. Using a 20wt% solution of PEI to impregnate the fibers, a pseudo-equilibrium performance of 0.65 mmol CO2 /g fiber was demonstrated on dry simulated air at 25oC and 1.04 mmol CO2/fiber with 50% humidity indoor air. It was found that 10wt% solution fibers had the best kinetic uptake and achieved a productivity of 1.05mmol/g fiber/hr with realistic air velocities of 1 m/sec and assuming 20% loss of CO2 during desorption. 99% of the CO2 desorbed during the first five minutes of desorption.
DOI: 10.2172/1884555