Gas consumption in thermal power plants shot up 24% between 2014 and 2019 as the National Iranian Oil Company substantially raised gas output during the period, especially in the South Pars Gas Field, the Thermal Power Plants Holding Company deputy for renovation affairs said.
“Natural gas accounted for 72% of the total fuel consumed in thermal power stations in 2014,” Aliasghar Abdoli was quoted as saying by Bargh News website. The figure reached 89% in 2019 – up 24%, he added.
According to the official, five years ago liquefied fuels, namely mazut and diesel, comprised 15.3% and 12.7% of the total fuel consumption in the (power) plants, respectively.
In 2019, mazut use plummeted to 6.8%, but diesel rose by 1.2% and stood at 13.9%.
Referring to the plants’ restrictions in receiving sufficient gas in the past three weeks, he said power stations near big cities (Besat in south Tehran, Montazer-Qaem near Karaj and Eslamabad close to Isfahan) have not yet started using mazut.
“Power plants do not want to use mazut simply because it doubles maintenance costs, increases water consumption and decreases output. However, they must keep generating power come what may.”
Most thermal power plants are natural-gas based and feeding them liquefied fuels (except in emergency cases) will have long-term adverse effects like damaging machinery and parts.
When fossil fuel is burned, it releases CO2, nitrogen oxides (NOX) and sulphur oxide (SOX) into the atmosphere, which contribute to smog and acid rain.
TPPHC has decreased CO2 emissions by 15% over the past eight years, he said without providing details. Moreover, gas-fired power stations are being equipped with NOX control technology that curbs pollution by up to 50%.
Referring to SOX, he said if the Oil Ministry provided power plants with low-sulfur mazut (0.5%), air pollution would be less of a concern.
The South Pars field off the Persian Gulf that shared with Qatar, is being developed in 24 phases. Close to 680 million cubic meters per day of gas is currently extracted from the field.
Average Efficiency
In related news, Mohsen Tarztalab, head of TPPHC, said the average efficiency of thermal power plants has reached 37%.
“Conversion of single-cycle power plants (gas-powered) into combined cycles can help raise efficiency to 40%.”
Thermal plants account for 80% of Iran’s total power generation (84,000 MW). Steam-powered, gas-powered and combined-cycle plants constitute 19 gigawatts, 25 GW and 23 GW of the thermal units, respectively.
Of the total thermal output (67 gigawatts), 25 GW is produced by gas-powered facilities that have efficiency levels of less than 32% and their conversion to combined cycles can help increase thermal efficiency by 4% and save12 billion cubic of natural gas a year.
In a thermal power station heat is converted to electric power. Energy from a thermal power plant not utilized in power production must be released into the environment in the form of heat. This wasted heat can go through a condenser and be disposed with cooling water or in cooling towers.
A combined-cycle power plant produces up to 50% more electricity from the same fuel than a traditional simple-cycle plant. The waste heat from the gas turbine is routed to a nearby steam turbine, generating extra power.
