Tokyo power system creaks under summer heat

Tokyo's biggest consumers of electricity were asked to curb their use of power Wednesday afternoon as consumption came close to exceeding what the power utility was able to deliver.

At lunchtime, Tokyo Electric Power Co. (TEPCO) said it was invoking a clause in contracts with major consumers, such as large office buildings and factories, that allows it to reduce power supply in return for lower charges. It is the first time in 17 years that TEPCO has taken such a measure.

"TEPCO expects to face significant difficulty in keeping electricity supply in balance with increasing demand," the utility said.

As the temperature in the Tokyo region climbed to around 35 degrees Celcius (95 degrees Fahrenheit), the use of air conditioners and other cooling systems pushed total power consumption to 61.5 million kilowatts, only 1 million killowatts below what the utility is able to supply.

Reducing power to large consumers saved an estimated 150,000 kilowatts. TEPCO also got government permission to restart an idle hydro-electric power station to push its total capacity to 63.7 million kilowatts.

Temperatures have been rising in Tokyo in recent years as a result of the "heat-island" effect. Concrete absorbs heat all day and lets it out at night, meaning nights are hot and humid and residents keep their air-conditioners running non-stop.

As a result of the electricity crisis, businesses and consumers are beginning to show keen interest in energy-saving products, and companies are pushing power-saving attributes of everything from lightbulbs to flat-panel televisions.

Tokyo's power problems can be traced to a patchy safety record at the utility, which has led to several of its plants, including the hydro electric facility, being stopped for repairs or investigations.

A powerful earthquake that hit Japan a month and a half ago also contributed to the problem. The earthquake occurred very close to TEPCO's Kashiwazaki Kariwa nuclear power plant and forced all reactors to be shut down immediately. The plant, which is the world's largest by power output, has been forced to remain closed while repairs are made and investigations continue into a number of small accidents that happened when the quake struck. None caused the release of dangerous levels of radiation, according to TEPCO and the Japanese government.