Natural gas fired combined cycles with low CO2 emissions

This paper assesses performances and economic viability of CO2 removal by c hemical absorption from the flue gases of natural gas-fired Combined Cycles . more specifically for two configurations: one where CO2 is removed ahead of the stack without modifying the power cycle: the other where part of the flue gases is recirculated to the gas turbine. thereby reducing the flow t o be treated by chemical absorption. In both cases sequestered CO2 Is made available at conditions suitable to storage into deep oceanic waters. Perfo rmances and cost of electricity are evaluated for systems bused on large. h eavy-duty turbines representative of state-of-the-art "FA" technology. Carb on sequestration re duces net plant efficiency and power output by about 10 percent and increases the cost of electricity from 36 to aborts 50 mills/k Wh, Flue gas recirculation warrants slightly higher efficiencies and lower costs. CO2 removal is rvenrualh compared with other strategies for the redu ction of CO2 emissions, like switching existing coal-fired steam plants to natural gas or replacing existing steam plants with conventional CCs. At cu rrent fuel prices the latter appears the option of choice, with a cost of a bout $25 per tonn of avoided CO2 emission.