EghtesadOnline: Tous Thermal Power Plant in Khorasan Razavi Province slashed use of mazut as feedstock in the first half of the current Persian calendar year (March 20-Sept. 21, 2020) but is still among the big polluters due to rising diesel consumption, director general of the provincial Department of Environment said.
“In the first half of last year, the plant burned three million liters of mazut a day. With help from the Energy Ministry, more gas was supplied to the plant this year and its mazut consumption decreased sharply to 1,500 liters per day,” Bargh News quoted Touraj Hemmati as saying.
“However, the plant is a major source of pollution in Mashhad because it also uses diesel as feedstock that has increased by 2.5 times compared to last year,” he noted.
The DoE is in collaboration with the Energy Ministry and the provincial governorate to help ensure that the power plant receives enough gas and curbs use of polluting liquid fuels such as diesel and mazut.
Established in 1985, Tous Power Plant has a capacity of 600 megawatts, and meets 50% of the demand in the shrine city of Mashhad.
Regarding the grade of feedstock used in the plant, the manager for engineering and planning at the plant, Ali Reisianzadeh, earlier said: “We have no authority to determine the type and amount of fuel consumed in the plant. That is the function of the two ministries of energy and oil.”
He recalled two factors compelling the use mazut in the plant. “Due to the increase in gas consumption in households, especially in the cold season, mazut use rises as less gas is made available to the power plant(s).”
Diesel and mazut use, especially in the winter, along with temperature inversion, have a serious negative impact on air pollution.
Reisianzadeh referred to the production of mazut in refineries and sold to power plants as feedstock when “actually power plants have no interest” in using this liquid fuel because it damages machinery and equipment.
Mazut is not suitable for power plants because it doubles maintenance costs, increases water consumption and decreases output.
Most thermal power plants are natural-gas based and feeding them liquefied fuels has long-term adverse effects. Use of diesel and mazut instead of gas in power plants and other industries increases greenhouse gasses.
As more liquid fuels are burnt, more toxic fumes are released into the atmosphere making a bad pollution situation worse.
Although efforts are underway to discontinue mazut use in power plants, at least five major utilities including Neka in Mazandaran, Shahid Rajaee in Qazvin, Sahand and Tabriz in West Azarbaijan and Bandar Abbas in Hormozgan Province still use the dirty fuel when natural gas supplies dwindle in winter.
According to Mohsen Tarztalab, managing director of Iran's Thermal Power Plants Holding Company, by the end of the current year (March 2021), the efficiency of thermal power plants will increase by 1% to reach 39%.
Energy efficiency of a conventional thermal power station, considered salable energy produced as a percent of the heating value of the fuel consumed, is typically 33% to 48%.
Considering all the heat produced by gas and steam turbines, their efficiency is limited and governed by the laws of thermodynamics. Combined-cycle systems, however, have higher levels.