The national power supply indicator yesterday signaled “red” for the first time this year and will remain “red” through Friday due to hotter-than-expected weather that has prompted greater power demand, Taiwan Power Co (Taipower, 台電) said.

A “red” alert indicates that the electricity operating reserve has fallen below 900,000 kilowatts (kW), the state-run utility said.

“The mercury rose as high as 38.3? Celsius about noon in Taipei [yesterday], driving electricity demand up more than Taipower’s forecast,” spokesman Lin Te-fu (林德福) told reporters.

The maximum power supply capacity yesterday was 37.01 gigawatts, but after deducting the peak electricity consumption of 36.16 gigawatts at 2:09pm, the nation’s operating reserve was 846,000kW later in the afternoon, Taipower’s data showed.

Taichung Power Plant’s No. 1 generator, which can provide 550,000kW, went back into operation late on Sunday after a broken pipe was fixed, otherwise the power supply indicator would have hit “black” yesterday with only 296,000kW in operating reserve, a Taipower official said.

According to the company’s five-color scale, “black” means the reserve is less than 500,000kW and that the company could initiate electricity rationing.

The electricity contribution from wind farms, solar power and cogeneration units yesterday increased by 300,000kW from the day before, which also helped with power supplies, the official said.

Based on the Central Weather Bureau’s forecast, Taipower said it estimates the maximum power demand today will be 36.2 gigawatts, which would leave an operating reserve of 755,000kW, or a reserve margin of 2.09 percent.

The operating reserve is estimated to be 675,000kW, or a margin of 1.86 percent, tomorrow, Thursday and Friday, Taipower said.

Trial runs this week of a new power generator at a coal-fired power plant in Kaohsiung’s Dalin Township (大林) and one at a gas-fired power plant in Taoyuan’s Datan Township (大潭) could help ease the constrained electricity supply, Lin said.

Taipower pays close attention to the status of all power generators nationwide to prevent any malfunction that might affect the power supply, Lin said.

He declined to say if a generator malfunction could lead to a “black” alert and the possibility of electricity rationing.

Taiwan has experienced electricity rationing 57 times since 1988, the last time in 2002, Taipower’s data showed.

Taipower calls on the public to raise the temperature setting of air-conditioners in the afternoons to help reduce electricity consumption, Lin said.

If rationing starts, it would be implemented based on the standard operating procedure formulated by the Ministry of Economic Affairs, Taipower said.

The procedure stipulates that if a power shortage occurs, the company is to inform heavy users that rationing measures will be put in place the next day.

Taipower would first reduce power supplies by 5 percent to businesses that use more than 5,000kW, followed by a 5 percent reduction to those who use between 1,000kW and 5,000kW if the problem is not resolved.

Rationing would be increased to 10 percent or even 15 percent if the power supply becomes even tighter, it said.

If the power supply remains insufficient, rationing would be imposed on businesses that use less than 1,000kW, as well as households.

Additional reporting by CNA