Exergy and economic analyses of advanced IGCC–CCS and IGFC–CCS power plants

Abstract

We present exergy and economic analyses of two advanced fossil fuel power plants configurations: an integrated gasification combined cycle with advanced H2 and O2 membrane separation including CO2 sequestration (Adv. IGCC–CCS) and an integrated gasification fuel cell cycle with a catalytic gasifier and a pressurized solid oxide fuel cell including CO2 sequestration (Adv. IGFC–CCS). The goal of the exergy analysis was to evaluate the power generation and the exergy destruction of each of the major components. We estimated the capital, labor, and fuel costs of these power plants, and then calculated the internal rate of return on investment (IRR) and the levelized cost of electricity (LCOE). In the Adv. IGFC–CCS case, we chose a configuration with anode gas recycle back to the gasifier, and then varied the SOFC pressure to find the optimal pressure under this particular configuration. Using a base load generation price of electricity of $50/MWh, the IRR of the Adv. IGFC–CCS configuration was 4±3%/yr if the CO2 can be used for EOR and 1±3%/yr if the CO2 can only be sequestered in a saline aquifer. The IRR of the Adv. IGCC–CCS configuration with H2 and O2 membrane separation was 8±4%/yr if the CO2 can be used for enhanced oil recovery (EOR) and 3±3%/yr if the CO2 must be sequestered in a saline aquifer. The uncertainty here reflects the uncertainty in capital costs, operation & maintenance (O&M) costs, and CO2 sequestration costs.One goal of the economic analysis was to compare the IRR and LCOE of these configurations with the IRR and LCOE of other fossil fuel power plant configurations. For example, using capital/labor/maintenance cost estimates from the literature, we calculated the IRR and LCOE of conventional fossil fuel power plant configurations, including scenarios with CCS and scenarios with varying costs to emit CO2. We also present results on which power plant configuration yields the lowest value of LCOE as a function of the price of CO2 emissions and a function of the price of natural gas, holding all other variables constant. An Adv. IGCC–CCS–EOR configuration yields the lowest value of LCOE when the price of natural gas and the price of CO2 emissions are above the line between ($5/GJ, $10/tCO2) and ($2.5/GJ, $50/tCO2).