Theoretical assessment of integration of CCS in the Mexican electrical sector

Abstract

This research evaluates the current most advanced and proven Gas Turbine (GT) technologies in a 1 × 1 scheme (400 MW on average) for their application in CO2 capture schemes. It has been demonstrated that the minimum energy required for the separation of CO2 is higher in a Natural Gas Combined Cycle (NGCC) than in a coal-fired power plant. Therefore, existing schemes were evaluated to assess the increased CO2 content in the Exhaust Gases (EG) for a NGCC in order to help reduce the energy penalty and the investment cost in CO2 capture systems. The schemes analyzed were: Exhaust Gas Recirculation (EGR), Evaporative Gas Turbine (EvGT), Supplementary Firing Combustion (SFC), External Firing combustion (EFC) and alternating systems with Selective Exhaust Gas Recycle (S-EGR) and hybridization. The most common GTs used in Mexico: Mitsubishi (15%), Siemens (41%) and General Electric (GE) (44%) including M − 501 GAC, SGT6-8000H and GE7HA.01 models were evaluated in Thermoflex 26®. For these, Levelized Costs of Electricity (LCOE) of 31.46, 31.18 and 31.05 USD/MWh, respectively, were obtained. GE offers the lowest LCOE and the EGR system presented the lowest energy penalty when the CO2 capture system was modeled in HYSYS V8.6®. Implementation of EGR helped to improve the energy efficiency of the NGCC and increased the content of CO2 from 4.2 to 7.1 mol% at 40%EGR. Similarly, EGR helped to reduce the LCOE in the integrated system with CO2 Capture by 10 USD/MWh.