The photo is sourced from cpec.gov.pk
The 1,320 MW power plant will use a “supercritical” technology of power generation while the 330 MW plant will employ a “subcritical” one. The difference lies in the water heating temperature during coal combustion for the purposes of steam generation and subsequent electricity production. The threshold is the critical water point, which is reached at the temperature of 374 degrees Celsius and the pressure of 218.5 atm: these conditions dissolve the differences between liquid and vapour.
Whereas at “subcritical” coal-fired TPPs water is heated to no more than 374 degrees Celsius, this temperature reaches 566 degrees Celsius at “supercritical” TPPs and 760 degrees Celsius at “ultra-supercritical” ones. This leads to a difference in the efficiency of transforming thermal energy into electricity: the World Coal Association estimates that, while the efficiency is 33% for “subcritical” coal-fired TPPs, it can reach 44% for “supercritical” ones and about 50% for “ultra-supercritical” ones. The higher the efficiency, the less coal is required to generate a certain amount of electricity.
As for feedstock, the 1,320 MW power plant will use brown coal, which will be extracted from the adjacent coal seam with an output of 7.8 million tons per year. The project will make it possible to effectively double Pakistan’s coal production, which stood at 7.5 million tons in 2021. Meanwhile, the 330 MW power plant will use primarily imported feedstock, just like most of Pakistan’s coal-fired TPPs: in 2021, the country imported 19.6 million tons of black and brown coal, according to the International Trade Centre of UNCTAD/WTO.
In terms of the rates, at which coal-fired TPPs are commissioned, Pakistan was the fourth country globally in 2022, behind only China, India and Japan. According to Global Energy Monitor, Pakistan connected 2.6 gigawatts (GW) of coal-fired TPP to the grid last year, compared to 26.8 GW, 3.5 GW and 3 GW connected in China, India and Japan respectively. The top five was rounded out by Vietnam, with 1.9 GW of newly-commissioned coal-fired TPPs.
