Repair and maintenance of aging power plants cannot improve their low efficiency as expected and there is a critical need for modern equipment, head of Tehran’s Besat Power Plant said.
Regarding the 53-year-old Besat station, he said: “When it was built in 1968 its efficiency rate was 34%. Now it is below 30%. Although it is possible to make some improvement by efficient repair and maintenance, efficiency will not exceed the initial 34%,” the Energy Ministry news portal Paven quoted Masoud Sheykh as saying.
He stressed that innovation and modernization in the power sector is a must. "Modernizing old and ageing power plants is not a matter of convenience. It is a compulsion."
Reemphasizing the need to increase the efficiency of power plants by converting gas units to combined-cycle ones, Sheykh said: “The contract for the installation of an advanced gas turbine at Besat Power Plant was signed recently between Iran's Thermal Power Plants Holding Company and Mapna, the engineering and energy giant.”
As per the agreement, one ageing turbine in the facility will be replaced with a modern gas turbine (MGT-75) manufactured by Mapna. The new turbine will turn the simple-cycle power station into a combined-cycle unit.
The gas turbine, which has been manufactured by Iranian engineers is being installed at Besat. It will almost double the efficiency of the plant and increase production from 160 megawatts to 200 MW, Sheykh said.
Combined-cycle power plants have higher efficiency and lower energy consumption and are more environmentally friendly.
Cut by Half
Based on data from Iran Power Generation, Distribution and Transmission Company (Tavanir), the plant annually uses 500 million cubic meters of gas as feedstock. The new turbine will cut this by half.
One specific feature of the MGT-75 turbine is that not only does it run on gas, but can also use hydrogen as feedstock.
Benefiting from hydrogen in megacities like Tehran is crucial as the metropolis has been suffering from air pollution forever.
Adding hydrogen to natural gas is a major step toward decarbonization as its combustion process emits less greenhouse gases including CO2 and produces more energy.
The Besat facility consumes 18 million liters of water per day (18,000 cubic meters/d) to generate 1.2 billion kilowatts a year, accounting for a paltry 0.4% of the total annual national electricity output at 300 billion kWh.
Rapidly depleting water is extracted from six deep wells as water shortages continue to pose a serious risk to the overcrowded capital.
The ageing plant uses the equivalent of water used by 72,000 people in the capital in one day. Per capita water consumption in Tehran is 250 liters a day. The new turbine will cut water consumption to less than 800,000 liters a day.
The estimated useful life of a power plant is 20 years. In addition to being outdated, another problem with Besat is that it has a wet cooling tower that is preferred in regions where water is plentiful, like the coastal regions.
In wet cooling towers, heat transfer is measured by decrease in the process temperature and a corresponding increase in both the moisture content and the wet bulb temperature of the air passing through the cooling tower.
In areas like Tehran where access to water is limited, dry cooling techniques are used. As the name suggests, this relies on air as the medium of heat transfer, rather than evaporation from the condenser circuit. Dry cooling means that minimal water loss is achieved.
When the facility opened half a century ago, Tehran was not struggling with chronic water scarcity. But conditions have changed and the population has jumped from three million then to more than ten million now.
