Iran’s Thermal Power Plants Holding Company has started operations to decommission the most outdated power stations in the capital, director of planning at the Thermal Power Plants Holding Company said.
“Tarasht Thermal Power Plant in the west of Tehran has been generating electricity for more than 60 years while the estimated useful life of an electricity station is around 20 years,” Barq News also quoted Hamidreza Azimi as saying.
Cooling towers of the dilapidated gas-powered plant are being demolished and operations to build modern gas- and steam-powered units have commenced, he added.
“The new combined-cycle station with 60% efficiency will have six units, two of which are supposed to be synchronized with the national power grid in June 2022, when demand reaches its peak. The other four units will become operational one year later.”
Domestic contractors are carrying out the project and they have already placed orders for the purchase of equipment, including boilers, turbines, generators and transformers.
According to the official, the old power station was a traditional simple cycle 60-megawatt plant and its maximum efficiency stood at 30%. Nonetheless, the new plant will be equipped with F-class turbines that double efficiency, consume less gas and are more eco-friendly than the turbines in conventional power plants.
A combined-cycle power plant uses both gas and steam turbines to produce up to 50% more electricity from the same fuel than a traditional simple cycle plant. The waste heat from the gas turbine is sent to a nearby steam turbine to generate electricity.
Three thermal power plants in Tehran, namely Tarasht in west and Rey and Besat in the south, supply electricity to the megalopolis.
“Permits have been issued for the construction of a new power station with 60% efficiency near Rey in southern Tehran.”
Referring to the Rey Power Plant’s low efficiency, he said the facility is operating for more than four decades.
Efficiency Rate
Under Energy Ministry rules, new power plant units must have efficiency rates of at least 58%.
Azimi warned that if the rehabilitation of aging plants is delayed, maintenance costs will become prohibitive for the highly subsidized and apparently loss-making energy sector.
Iran's long-term plans to boost electricity output from the current 84,000 MW to 120,000 MW cannot be realized, unless new power plants come on stream, he added.
More than 80% of electricity output come from thermal plants that use fossil fuels.
Over two-thirds of Iran’s thermal power plants are owned and operated by private firms and generate almost 67% of the domestic thermal power.
With an installed capacity of 84 gigawatts, Iran ranks ninth in terms of thermal power capacity in the world.
Pointing to TPPHC's role in meeting power demand, Azimi said at least 85% of Iran's electricity needs are met by thermal power plants.
The Energy Ministry is gradually phasing out inefficient power plants, improving and expanding electricity infrastructure and acquiring modern technology. However, financial constraints have slowed the process.
Effective steps have been taken to convert conventional plants into combined-cycle units to improve efficiency and reduce pollution and costs.
Besat Station
Referring to the 52-year-old Besat station, Azimi noted that the facility consumes 18 million liters of water per day to produce 1.2 billion kilowatts a year that is 0.4% of the total annual national electricity output.
In addition to being old, the problem with Besat is that it has a wet cooling tower that requires plentiful water, such as in the coastal regions.
In wet cooling towers, heat transfer is measured by a decline in process temperature and a corresponding increase in both the moisture content and the wet bulb temperature of 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 involves minimal water loss.
The aging plant uses as much water as 70,000 people in the capital per day. Daily per capita water consumption in Tehran is 250 liters.
Aziimi noted that another advantage of replacing the Besat Power Plant is that water consumption will be lower, as the new station will save water by over 90%.
Tehran has more than five million power subscribers, of which 75% are households. At least 100,000 new customers join the subscription list every year, which has grown at a regular pace and piled pressure on utilities, such as water, electricity and gas.
TPPHC oversees dozens of fossil fuel power plants with an installed capacity of over 71,000 MW, constituting the bulk of electricity demand.
