Wang Noi Power Plant is a combined cycle power plant using both gas turbine and steam turbine together to produce electricity. The working principle is as follows:

Fuel (gas) is heated to a very high temperature in the combustion chamber of a gas turbine and mixed with the compressed air. The hot-air-fuel mixture moves through the gas turbine blades and makes them spin to drive the generator which is on the same shaft to produce electricity.

The exhaust heat energy from the gas turbine is captured in a heat recovery steam generator to produce steam to drive a steam turbine and another generator to produce additional electricity. A portion of the high pressure steam will pass through a pressure valve to drive the turbine again, while the low pressure exhaust steam is delivered to a condenser for water cooling and to the boiler.

Wang Noi Combined Cycle Power Plant uses natural gas from the Gulf of Thailand as main fuel and diesel oil as secondary in electricity generation. At present, the power plant has contractual generating capacity of 1,436 MW comprising