Iran has more than 120 thermal power plants that account for about 0.1% of total annual water consumption, the head the Thermal Power Plant Holding Company said.
"Iran's annual water consumption [extracted from ground and surface resources] tops 100 billion cubic meters, of which less than 130 million cubic meters are used in power plants annually, which is insignificant compared to the farming sector that gobbles up 90 bcm of water per year," the ministry's news portal Paven also quoted Abdolrasoul Pishahang as saying.
Of the total volume of water used in Iran, 2 bcm are used in industries, including petrochem plants, steel mills and power stations, he added, noting that as per the directive issued by the Energy Ministry in 2020, it is mandatory for all thermal power plants to use reclaimed wastewater [instead of potable water] in cooling towers.
“Wet cooling towers account for 70% of the total water consumption in power stations, that’s why replacing them with dry-cooling systems is on the TPPHC agenda,” he said.
Wet cooling towers have a high cooling capacity. However, due to their high water consumption, their use in arid regions that are struggling with water crisis can cause operational problems. In dry cooling towers, there is no direct contact between the working fluid and the ambient air, so there is no water loss in the process.
One dry cooling tower went on stream at Hamedan’s Shahid Mofatteh Thermal Power Plant in 2015, which reduced the power plant's water consumption from 3 mcm to 600,000 cubic meters. In other words, it has saved 2 mcm of water per annum so far.
Ramin thermal power plant in Ahvaz in southwest Khuzestan Province and Isfahan Power Plant in the namesake central province will soon be supplied with treated wastewater for cooling towers.
Renewable Resources
Drawing a parallel, Pishahang noted that the company’s annual water extraction from renewable water resources equals the amount of water used in Tehran in 33 days.
Household sector accounts for 7% of total water consumption.
Refuting the general belief that power industry is water-intensive, he said power plants have started tapping into unconventional resources as curbing water consumption is necessary, especially in Iran that has been grappling with disappearing underground water tables.
The UNESCO 2017 World Water Development Report says once treated, wastewater could be invaluable in meeting growing demand for freshwater and other raw materials.
Environmentalists and experts say industries can and must use recycled water for heating and cooling instead of the scarce and costly potable water.
Reports say 216 wastewater treatment plants are operating in Iran with an annual output of 1.2 billion plus cubic meters of reclaimed wastewater.
Treated sewage mostly goes for agriculture (57%) and the rest is consumed in industries, urban green spaces and replenishment of surface waters and groundwater resources.
Almost 70% of water consumed in households turn into sewage.
