In the first warning of its kind issued by the government, the ministry of economy, trade and industry said Tuesday it wants utility customers in areas served by Tokyo Electric Power (Tepco) to curb usage from 8am to 11pm.
Total consumption needs to be reduced by around 60,000 megawatt-hours, or roughly 10%, from projected levels to avoid the risk of widespread outages, the ministry said Monday.
Tepco on Monday entered into talks to receive electricity from other utilities to make up for potential shortfalls.
Economy minister Koichi Hagiuda asked households and businesses in Tepco’s area of jurisdiction to make “utmost efforts to save electricity” at a news conference on Tuesday morning.
The power warning is triggered when the reserve margin for electricity is seen sinking below the 3% threshold needed to ensure stable service.
The margin is forecast to fall below 3% during peak times Tuesday. A severe power shortage could trigger widespread outages across areas served by Tepco.
Demand for electricity is expected to ease on Wednesday as temperatures rebound.
METI and Tepco have asked homes and workplaces to keep their thermostats at 20°C and turn off unnecessary lighting starting Tuesday morning. The utility urged businesses to reduce energy use from Tuesday to Friday as much as possible without impacting their operations.
Power demand tends to rise during weekdays due to corporate activity. Tepco will fully tap its power supply and storage facilities to continue serving customers.
At least 10 fossil fuel power plants shut down in Japan following the earthquakes off the coast of Fukushima Prefecture late Wednesday night.
Shinchi Power Station in Fukushima Prefecture has been shut down by an equipment failure, with no timetable set for restarting operation. Hirono Thermal Power Station, also in Fukushima, remains closed as well.
A unit at Isogo Thermal Power Plant in Kanagawa halted operations Sunday for an unrelated problem. Cloudy skies likely will reduce output at solar farms on Tuesday as well.
Japan’s regional power grids lack enough capacity for sharing electricity across boundaries. The increased use of weather-dependent renewable energy sources also adds unpredictability to the power supply.
Tepco had urged users to save electricity amid a power crunch on Friday night. The utility likely will face continued strain on its ability to deliver power until the thermal power plants resume operation.