India’s National Thermal Power Company (NTPC) has commissioned the North Karanpura coal-fired thermal power plant (TPP) in the state of Jharkhand in the east. The three-unit facility, with a combined capacity of 1,980 megawatts (MW), is India’s first coal-fired power plant to use air-cooled condensers to save water in power generation.
Capacitors that convert superheated vapour to liquid are a solid-fuel power generation chain component. When coal is burned, it heats a water boiler, transforming it into steam that operates a turbine which rotates a generator to produce electricity. The exhaust steam is directed to the condenser, which cools it to the state of water, which, after being cleaned, can be reheated in the boiler, ensuring a closed cycle. In the electric power industry, water-cooled and air-cooled condensers are used concurrently: in the first case, approximately 50 tonnes of cooling water are required per tonne of steam, whereas in the second case, it is not required at all.
The North Karanpura TPP proposition originally suggested employing the utilisation of a condenser that was water-cooled. In this scenario, there would be an annual consumption of 55 million cubic metres of water throughout generating electricity. It was necessary to store approximately the same amount of water, which would necessitate constructing a dam with a height of 22.5 metres (through one of the tributaries of the Damodar River) and a total area of just over 2,000 hectares. However, in subsequent product iterations, an air-cooled condenser was favoured over a water-cooled one. As a consequence, the total amount of water that will be required on an annual basis for the generation of electricity will not exceed 20 million cubic metres of water will be supplied by a low-pressure dam located on the property of the thermal power plant. This dam will be equipped with a “gate” that will allow water to flow through it.
The North Karanpura power plant is one of the “supercritical” thermal power plants, which by the beginning of 2023, accounted for 30% of the coal-fired generation capacity in India. According to the Global Energy Monitor, the share of “subcritical” coal thermal power plants was 69%, and “ultra-supercritical” – was 1%. One of the differences is the efficiency of converting thermal energy into electricity: if the efficiency of “subcritical” TPPs is 33%, and “supercritical” – 44%, then “ultra-supercritical” – is about 50%, according to the World Coal Association.
India ranks second worldwide in terms of installed coal-fired generation capacity. According to the Global Energy Monitor, by the beginning of 2023, 284 coal-fired thermal power plants were operating in the country with a total capacity of 234 gigawatts (GW), while in China – 1135 TPPs per 1093 GW, and in the rest of the world – 1039 TPPs per 755 GW.