Vietnam is advising power-consuming manufacturers in the south to stagger production while the Nam Con Son gas pipelines that feed power plants undergo maintenance, an official at state utility Vietnam Electricity (EVN) said.
Gas supply to two power plants with a combined capacity of about a quarter of the country's total was to halt from Sept. 15 to the end of the month due to maintenance on the pipelines coming in off Vietnam's southern coast.
The Nhon Trach and Phu My power plants are planned to run by domestically produced diesel during the Sept. 15-24 shutdown, producing up to 3,000 megawatts, depending on demand, said Nguyen Tien Vinh, director of Petrovietnam's power department.
Trinh Ngoc Khanh, head of EVN's planning department, told Reuters power supply will be "strained" during the maintenance and the shift to diesel has not gone smoothly leading to "sudden blackouts", he said.
The Ministry of Industry and Trade is advising power-consuming companies to stagger production during the Nam Con Son maintenance, he said.
"Cement and steel companies have stockpiles anyway. They should take this chance to reduce production or take a break for maintenance work," he said.
Many foreign invested manufacturers operate in and around Ho Chi Minh City and may be affected by the power shortage.
The two power plants have combined capacity of 5,000 megawatts. EVN, the country's power monopoly, has said total generation capacity was about 21,600 megawatts.
Vietnam has suffered a chronic and deepening power shortfall, but in recent months, with consumer prices soaring and gross domestic product growth under pressure due to anti-inflation measures, supply has exceeded demand, state media have quoted the industry and trade ministry as saying.
Ho Chi Minh City's electric company, a subsidiary of EVN, said on its website the pipeline maintenance would have a large impact on power supply in the Southern area.
It promised to keep supply secure during the maintenance period, but was "actively working with industrial parks and export zones to ask companies to change working schedules avoiding peak hours and switch production to weekends".
Two other gas-fired power plants, Ca Mau 1 and 2, will be closed for maintenance at different times in October, said an official with PV Power, the electricity producing arm of Petrovietnam.
Ca Mau 1 would be shut from the start of October until an unspecified date, and Ca Mau 2 would be turned off from mid-October possibly through mid-November, said Vu Huy Quang, general director of PV Power.