The Thermal Power Plant No. 4 () is a coal-fired cogeneration power station in Bayangol, Ulaanbaatar, Mongolia. With a total installed generation capacity of 663 MW, it is currently Mongolia's largest power station.
The first generating unit of the power station was commissioned in January1983. All of the six generating units of the power plant were completed in 1991. In late 1990s, the power station began its overhaul project which were divided into two phases. The first phase which started in 1998 and completed in 2001, saw the revamping of its boiler no.1 until boiler no.4. The second phase which started in 2001 and completed in 2007, saw the revamping of its boiler no.5 until boiler no.8.
On 8February2017, the power station also received two emission analyzers from the Japan International Cooperation Agency to measure smoke and pollutants with a total cost of JPY37.6million. On 13September2017, a fire broke out at one of the plant's transformer. The fire was quickly extinguished by 50 firefighters from five units.
The primary fuel for the power station is brown coal. It can also run on heavy fuel oil if there is a shortage on brown coal availability. It consists of eight boilers and six generating units, three 80MW units and three 100MW units, making it the largest power station in the country. In 2023, the power station used a total of 19.2millionm<sup>3</sup> of water to generate power. In 2011, the power plant generated 2,691GWh of electricity.
It also acts as a district heating for Ulaanbaatar. It has a heat supply capacity of 6,820GJ/h and annual heat generation of 16,871TJ in 2020.
The plant supplies electricity to 58% loads of Ulaanbaatar.
In 2010, the power plant employs around 1,400 personnel for its operations, maintenance and other works.
In 2011, the power plant received a revenue of â®124,168million from its electricity and heat selling.