Heat Challenges Japanese Grid

June 27, 2022

Washington Post:

In a blistering hot June around the Northern Hemisphere, in which heat records have fallen on every continent, Japan is the latest to swelter. On Saturday, temperatures there shot above 104 degrees (40 Celsius) for the first time on record during the month, another clear sign of the sweeping effects of human-caused climate change.

The mercury soared to 104.4 degrees (40.2 Celsius) in Isesaki, a city of more than 200,000 people about 50 miles northwest of Tokyo. That marked Japan’s hottest temperature ever observed during June.

The scorching temperatures — both in Japan and elsewhere — are occurring as summer has barely begun with the typically hotter months of July and August still to come.


Japan is asking Tokyo residents to conserve power, with unusually hot weather stretching the city’s grid as fears increase that the heat could last for longer.

Electricity supply in the capital will continue to be tight Tuesday after households, businesses and utilities took steps Monday to help avoid any blackouts.  The country’s government extended a power supply advisory for Tokyo which calls for curbs on consumption.

Sony Group Corp. turned off lights illuminating its logo at some of its bases, convenience operator Seven & i Holdings Co. changed meal-preparation times and electronic store operator Yamada Holdings Co. switched off the majority of display televisions, lights and cooling units.

The country’s grid coordinator ordered power sharing among regional utilities to supply Tokyo Electric Power Co. Those measures appear to be helping to ease pressure, and the city’s power reserves are now forecast to be above the minimum level required for grid stability. While hot weather is expected to keep power supply tight in the capital for the rest of the week, it’s unlikely Tokyo will face blackouts as generation in the rest of the country is strong.

Japan’s latest power crunch comes amid expectations of a long summer of pressure on electricity networks across much of Asia, with blistering heat seen raising demand just as global fuel shortages limit supply. High temperatures and an industrial rebound are already lifting consumption in key regions in northern China and Taiwan, while households and industry face the impact of surging power bills.

Temperatures in Tokyo will be as high as 35 degrees Celsius (95 Fahrenheit) this week, according to the country’s meteorological agency, above the 30-year average of 22.5 Celsius. The rainy season in the greater Tokyo area ended the earliest on record going back to 1951, pointing to longer and hotter periods that’ll pressure the grid.

The nation’s meteorologist expects hotter-than-normal weather through the summer, and forecasts temperatures to surge over the next month. Power prices are already trading at a record high for this time of year — a trend that is likely to continue as households ratchet-up air conditioning.

Japan in March issued a power supply warning, the first of its kind, after supply neared critical levels in Tokyo and has since introduced a new system to warn people to prepare for potential crunches. Under the new methodology, the government will issue a supply advisory a day before if reserve ratios are expected to drop below 5% and will ramp it up to an alert if that figure is seen slipping under 3%, the minimum level necessary for a stable grid.

Tokyo residents have been asked to turn off lights in rooms they are not using and to use air conditioning units in an appropriate way. The government will increase generation from thermal plants and the grid operator ordered power sharing to help tackle the crunch, it said. The period around 4:30 p.m. is crucial because solar power generation begins to decline as the sun goes down.

The measures appear to have had success Monday. The power reserve ratio, which measures the spare capacity of electricity, rebounded to around 7.5% for the Tokyo area around 5 p.m. It had earlier been seen below 1%. Officials expected the ratio to be at about 3.9% during the same period on Tuesday.

New York Times:

The warming of recent decades has already made it hard for scientists to know what to call a heat wave and what to treat as simply a new normal for hot weather, said Andrew Dessler, a climate scientist at Texas A&M University.

If the threshold for a heat wave is just the mercury exceeding 100 degrees Fahrenheit for days in a row, for instance, then it’s “not at all unexpected,” Dr. Dessler said, to see them occurring more regularly in several regions at once. “As time goes on, more and more of the planet will be experiencing those temperatures, until eventually, with enough global warming, every land area in the mid-latitude Northern Hemisphere would be above 100 degrees,” he said.

Yet even when scientists look at how often temperatures exceed a certain level relative to a moving average, they still find a big increase in the frequency of simultaneous heat waves.

One recent study that did this found that the average number of days between May and September with at least one large heat wave in the Northern Hemisphere doubled between the 1980s and the 2010s, to around 152 from 73. But the number of days with two or more heat waves was seven times higher, growing to roughly 143 from 20. That’s nearly every single day from May to September.


One Response to “Heat Challenges Japanese Grid”

  1. John Oneill Says:

    If the Japanese really want more power, considerably cheaper and far cleaner than the coal and gas they’re mostly relying on now, they have at least sixteen reactors sitting idle. The government wants them on, but local mayors and courts are keeping them shut down. Most are on the east coast, which is far less susceptible to tsunamis than the west – though Onagawa was actually closer to the focal point of the Great Tohoku quake than Fukushima Daiichi, and survived almost unscathed.

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