EghtesadOnline: Almost 25% of the electricity produced in the last fiscal (ended in March) was generated from renewable sources (steam, water, nuclear, wind and solar), chief executive officer of Iran’s Thermal Power Plants Holding Company said.
“An estimated 313 billion kilowatt hours of power was produced in 2019, of which one-fourth or 80 billion kWh was with the help of steam units in combined cycle power plants, hydro power stations, the Bushehr Nuclear Power Plant and renewables,” Mohsen Tarztalab was quoted as saying by Bargh News website.
Referring to share of steam, he said it accounted for 42 billion kWh and helped save 11 billion cubic meters of natural gas in one year.
Combined cycle units employ a heat recovery steam generator that captures heat from high temperature exhaust gases to produce steam, which is then supplied to a steam turbine to generate additional electric power.
These types of power plants use both gas and steam turbines to produce up to 50% more electricity from the same fuel than traditional power plants.
“Conversion of 18 gas-fired plants (total capacity 7,500 MW) to combined cycle plants is underway based on buyback contracts with private companies,” he said without elaboration. Completion of the projects would annually save 12 bcm of gas in thermal power plants
National Iranian Gas Company delivers close to 100 million cubic meters of gas to more than 100 thermal power stations across the nation every day.
According to the TPPHC boss, producing power from non-fossil sources helped reduce greenhouse gas emissions by as much as 40 million tons in 2019.
Bargh News added that in 2019, (of the 80 billion kWh of power generated from non-fossil sources) hydroelectric dams produced over 28 billion kilowatt-hours of electricity. Bushehr Nuclear Power Plant accounted for nearly 9.9 billion kWh and the balance (100 million kWh) came from renewables.
Energy efficiency of a conventional thermal power station is typically around 30%. Considering the amount of heat produced by gas and steam turbines, their efficiency is limited and governed by the laws of thermodynamics.
Thermal plants account for 80% of Iran’s total power generation (84,000 MW). Steam, gas and combined-cycle plants constitute 19 gigawatts, 25 GW and 23 GW of thermal output, respectively.
Of the total thermal output (67 gigawatts), 25 GW is produced by gas-powered facilities that have efficiency levels below 32%.
According to the official, up until 2015 liquefied fuels, namely mazut and diesel, comprised 15.3% and 12.7% of the total fuel consumption in thermal plants, respectively. In 2019, mazut use plummeted to 6.8%, but diesel rose by 1.2% to nearly 13.9%.
With installed capacity of 67 GW, Iran ranks ninth in global thermal power capacity. Close to 21 GW comes from facilities built more than three decades ago and should be either phased out or renovated. Estimated useful life of an electricity plant is 20 years.
“To rehabilitate the old plants TPPHC requires at least $3 billion per year,” the CEO said.
A portion of the cost can be met by borrowing from the National Development Fund of Iran, the country's sovereign wealth fund. However, experience shows that power plant operators cannot repay the loan on time.
About 60% of the power plants are run by the private companies that sell power to the state-run Power Generation, Distribution and Transmission Company (Tavanir). It has been reported that Tavanir normally does not pay its bills on time as a result of which plants encounter major financial difficulties.