Japan's electricity grid creaked on Thursday under the strain of Tokyo's hottest June since records began, but a power crunch that could have deprived tens of millions of electricity was narrowly averted and authorities prepared to lift warnings.
Temperatures of nearly 40 Celsius (104 Fahrenheit) were marked in some parts of greater Tokyo, home to 37 million people, on the sixth day of a heatwave that began after the earliest end to the capital's rainy season in decades.
Maximum highs are not forecast to drop to 30C (86F) before Tuesday.
But power outages were averted, despite the loss of output from a 600-megawatt (MW) plant even as generators feeding Tokyo worked up to carry their load with only about 3% reserve capacity, the level below which blackouts can occur.
Authorities said they would lift a warning of short power supplies that had been in effect for four straight days.
"Thanks to everybody's efforts, we were able to curb demand to a certain extent," said the Ministry of Economy, Trade and Industry.
In the morning, before the 600-MW plant was pulled from service, national grid monitor OCCTO had forecast the Tokyo area's critical period of 3% margin for 4.30 p.m. to 5 p.m. The lost plant was not expected to resume generating until the evening.
The industry ministry had issued a power shortage warning for a fourth day in areas around the city, urging households and businesses to save electricity, without stinting on air conditioning where doing so would endanger health.
Some 105 people were taken to hospital with heatstroke on Thursday, the Tokyo Fire Department said. A man in his 50s died and a woman in her 50s was in critical condition.
Temperatures this month have been the highest since record-keeping began in 1875.
The temperature in central Tokyo was 36.4C (97.5F) at 1:00 p.m. (0400 GMT) while the town of Hatoyama, north of the capital, sweltered at 39.7C (103.4F).
TURNING OFF THE LIGHTS
Some firms, such as auto parts maker Yorozu Corp, are scaling back shifts to save power while others, like retailer Seven & i Holdings and tech giant Sony, have asked employees to save power by turning off lights and other devices.
Automaker Nissan Motor said it was operating generators at its Tochigi plant north of Tokyo from Wednesday to Friday, while calling on offices and factories to save energy.
SoftBank Corp said it was easing up on air-conditioning, letting the temperature in its facilities rise to 26C from 25C.
The government and utilities had been preparing since spring to deal with tight power supplies during the period of peak summer demand, but that only officially begins on July 1, Friday.
The power squeeze has been expected with the suspension of generating by some power plants after March earthquakes in the Fukushima area, a long-term drop in the number of thermal power plants amid a push for decarbonisation, and delays to the restart of nuclear reactors because of stricter regulation following the Fukushima disaster in 2011.
To deal with the squeeze, the government and utilities have rebooted ageing gas-fired power plants and juggled maintenance schedules at nuclear reactors.
Japan's biggest power generator, JERA, planned to restart a 45-year-old gas-fired unit in Anegasaki, near Tokyo, on Thursday, followed by a 44-year-old unit at Chita in central Japan on Friday.
(Reporting by Yuka Obayashi and Nobuhiko Kubo; Additional reporting by Satoshi Sugiyama, Sam Nussey, Elaine Lies and Kantaro Komiya; Editing by Kenneth Maxwell)
