Typical flue gases from natural gas-fired power plants may contain 8-10% CO2, 18-20% H2O, 2-3% O2, and 67-72% N2; typical flue gases from coal-fired boilers may contain 12-14 vol% CO2, 8-10 vol% H2O, 3-5 vol % O2 and 72-77% N2.