Steam power generation is a power generation method that takes advantage of the expansive power of steam. Heat produced by burning fuel such as heavy oil, LNG (liquefied natural gas), or coal creates high-temperature, high-pressure steam. This steam is used to turn a steam turbine impeller, causing a generator attached to the turbine to move and generate power. With steam power generation, thermal energy is used in a relatively low-temperature range (600°C or below). The thermal efficiency* of steam power generation is in the 41.6% to 45.2% range.
*Lower heating value [LHV]: The value indicates energy produced when fuel is burned, excluding the heat of vaporization (condensation heat) of the water content in fuel and the steam generated from burning.
Combined-cycle power generation is a power generation method that combines a gas turbine and steam turbine.
It combines gas turbine power generation, by which fuel in compressed air is burned to generate combustion gas whose expansive power is then used to turn a generator; and steam power generation, by which the residual heat from the exhaust gas is recovered to turn a steam turbine. As a result, a high thermal efficiency of 47.2% can be obtained. Also, since it consists of a small gas turbine and steam turbine, operation starting and stopping are quick and easy, and fluctuations in demand can be quickly met.
ACC power generation* is a power generation method that has further developed combined-cycle power generation and achieved dramatic improvement in energy savings, flexibility, reliability, and eco-friendliness. By increasing the combustion gas temperature at the gas turbine inlet from the existing 1,100°C class to the 1,300°C class, a thermal efficiency of 54.1% to 57.2% is achieved with ACC power generation.
*ACC (Advanced Combined Cycle) power generation: An improved version of combined-cycle generation
MACC power generation* is a high-efficiency, large-capacity power generation method that is based on the ACC power generation system and further increases the combustion gas temperature at the gas turbine inlet. Through technical innovations such as the development of heat-resistant gas turbine materials and gas turbine steam cooling, higher temperatures up to the 1,500°C class are achievable, resulting in a thermal efficiency of 58.6%.
*MACC (More Advanced Combined Cycle) power generation: 1500°C-class combined-cycle power generation
By increasing the combustion gas temperature at the gas turbine inlet to the 1,600°C class, MACC II power generation* surpasses the 58.6% thermal efficiency of MACC power generation, achieving a world-best thermal efficiency of about 61%.
*MACC (More Advanced Combined Cycle) II power generation: 1600°C-class combined-cycle power generation