To achieve energy efficiency improvement is used to lower temperature for emission gas at catalyst inlet, or to reduce/stop using steam to reheat emission gas. Saved energy from this process can be used as power source in order to increase generation efficiency. Dry emission gas treatment, on the other hand, is the technology to increase generation efficiency by using highly efficient desalination materials including highly-responsive slaked lime and sodium type chemicals in order to comply with air pollution standards and reduce used steam volume for reheating emission gas. If dry emission gas is available, reheating is possible only with the temperature of 45℃ in order to expect generation efficiency by reducing steam volume for reheating. Retention energy of emission gas from combustion is calculated by emission gas multiplied by specific heat and temperature. In order to obtain more heat recovery from combustion emission gas, it is necessary to reduce not only exothermic loss from boiler facilities but emission calorie of emission gas coming out of boiler facilities. In order to reduce emission calorie of emission gas, it is efficient to realize temperature lowering for the emission gas temperature from the exit of heat recovery facility and reduce emission gas volume. When applying low temperature catalysts, the energy saving features from 0.03% to 2.52% (average 1.28%). When increasing the excess air ratio to 2.0, generation efficiency decreases by 0.41%. When the inlet temperature of the catalyst bed was changed from 210℃ to 180℃, greenhouse gas reduction results were 47.4, 94.8, 118.5, 142.2 thousand tons-CO₂/y, CH₄ was calculated to be 550.0, 1100.1, 1375.1, 1650.1 kg-CH₄/y, and N₂O was 275.0, 550.0, 687.6, 825.1 kg-N₂O/y. In the case of high efficiency dry flue gas treatment, reduction of greenhouse gases by the change of temperature 120~160℃ and exhaust gas 5,000 ~ 6,500 m³/ton is possible with a minimum of 355,461 ton/y of CO₂ and minimum 4,125 tons of CH₄/y to a maximum of 6,325 ton/y and N₂O to a minimum of 2,045 kg/y to a maximum of 3,135 kg/y.