Iran has permitted licensed cryptocurrency mining machines to resume operations after a three-month lull ordered by former President Hassan Rouhani.

Around seven percent of world cryptocurrency mining by powerful computers that use a lot of electricity is estimated to be taking place in Iran. The world’s cheapest electricity rates in the country encourage to lucrative business, in some cases with the involvement of some Chinese entities.

Iran experienced renewed electricity shortages in June when temperatures rose and air-conditioning units were turned on. The controversial practice of cryptocurrency mining was banned for three months, although tens of thousands of illegal, underground computers continued to work.

Electricity shortages are again expected in the winter, as Iran is chronically short of power generation due mainly to lack of investments in the sector. A severe drought in 2021 has further reduced power generation as most dams are more than half empty.

Although some officials have said that crypto mining only uses 300 megawatts of power, others have warned that usage is much higher and it can threaten to power grid.

Local media have been reporting that even in some government offices illegal crypto machines have been operating. The director of Tehran’s stock exchange Wednesday announced his resignation after cryptocurrency mining machines were uncovered at the offices of the organization.