Air conditioners and lights stay on in Tokyo

Thursday, 23 August 2007 Tokyo Electric Power Company (Tepco) has taken emergency measures for the first time in 17 years to secure supplies as its largest plant remains offline and Japan swelters in a summer heatwave.

The utility has asked some industrial customers to reduce their electricity usage, and readied a pumped storage hydroelectric power station for use.

With August demand forecast to peak at 61,100 MWe and supply capacity at only 62,750 MWe, the utility prepared the 900 MWe Shiobara hydroelectric power station by pumping water from the lower dam to the upper dam at night (a time of low energy demand), in readiness for the expected peak demand the next day.

Peak demand typically comes at around 2-3 pm during summer heatwaves, when air conditioner use is at its greatest. Twenty-three companies with load management contracts were asked to cut down on their energy usage by 150-200 MWe. Tepco was also taking steps to secure a stable electricity supply by increasing output at its hydro and thermal units and buying electricity from other utilities and self-generators.

Consumers were also asked to play their part. "In order to prevent power outage from happening, we kindly ask all of our customers to reduce electricity usage. We apologize for the inconvenience during such a heatwave," the company said in a press release. Japan's Economy Trade and Industry Ministry also asked industries and households to try to reduce energy use by turning up the preset temperatures of air conditioners and not using lighting during the daytime.

The seven-unit Kashiwazaki Kariwa nuclear power station, which has a capacity of around 8000 MWe, remains shut down since Niigata prefecture region was hit by a magnitude 6.8 earthquake on 16 July. Although the reactor and turbine buildings and major components do not appear to be damaged, detailed checks are still being carried out by Tepco and Japan's Nuclear Industrial Safety Agency (NISA). The plant is not expected to restart before the end of the year.

A separate announcement by NISA of a decision to extend the interval between regular checks at nuclear power plants from 13 to 24 months should enable reactors to operate for longer periods and with greater efficiency. The new system would be introduced in the next financial year.

Japan is not alone in asking its consumers to be energy-efficient during the hottest days of summer. In the USA, Progress Energy Florida reported a new record peak demand, recorded between 4pm and 5pm on 20 August. "Hot, dry weather increases the demand for energy, and we are working to ensure a reliable power supply," said Jeff Lyash, president and CEO of Progress Energy Florida. "Our system is operating as designed, and we don't anticipate any issues meeting demand, but we always encourage our customers to be as energy-efficient as possible."

Further information

Progress Energy
Tokyo Electric Power Company (Tepco)

WNA's Nuclear Power in Japan information paper

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WNN: Kashiwazaki Kariwa nuclear units shut down on earthquake