Tokyo faces tight power supplies as rainy season ends

The Japanese government has warned that electricity supplies in Tokyo will be tight on 27 June and asked consumers to step up power-saving efforts, after the earliest end to the rainy season in over 70 years led to unusually hot weather.

The rainy season in Japan's Kanto-Koshin area, which includes the capital Tokyo, appears to have ended on the earliest date on record since 1951, the Japan Meteorological Agency (JMA) said today. The resulting hot weather, combined with the closure of several thermal power units to prepare for the peak summer electricity demand season, has tightened power supply.

The Kanto-Koshin region, that includes capital Tokyo, as well as the southern Kyushu and central Tokai areas are likely to experience sunny weather for many days over next week because of high pressure, implying the areas have finished the rainy season, the Japan Meteorological Agency (JMA) said on 27 June. The declaration for the Kanto-Koshin region came 22 days earlier than average and 19 days sooner than last year.

The early onset of summer weather has already hit the Tokyo area, with the unusual hot and humid weather creating additional electricity demand for cooling purposes. Temperatures in central Tokyo marked 36.2°C on 26 June, the highest temperature for June, the JMA added. Power demand in Tokyo jumped by 17pc from a week earlier to 34GW during the week to 26 June, according to national power agency the Organisation for Cross-Regional Co-Ordination of Transmission Operators (Occto).

The trade and industry ministry (Meti) has warned that power supplies in Tokyo will be strained for 27 June and called for enhanced power-saving efforts from power consumers, especially towards the evening hours.

The Occto has ordered four regional grid firms in Hokkaido, Chubu, Hokuriku and Kansai to send a total of 912.1MW of electricity to Tokyo Electric Power (Tepco) Power Grid, which manages the power transmission network in the Tokyo area, during 10:30-20:00 Japan time (1:30-11:00 GMT) on 27 June. Tepco Power Grid is also expected to secure an additional 710MW for that day.

The extra supply would help the Tokyo area ride out a possible power shortage, with the ratio of the area's power surplus supplies increasing to more than 3pc, the minimum reserve level needed to tackle any emergencies such as unexpected power plant closures and a hike in peak demand. The area has been forecast to have a surplus of 2.8pc for 16:00-16:30 and 1.2pc for 16:30-17:00 as of 11:00 on 27 June.

The arrival of hot summer weather came sooner than expected, meaning that all thermal power plants were not sufficiently ready for operations to meet a hike in electricity demand. Several power units are still under pre-summer maintenance checks, but will gradually resume operations and help mitigate the impact of a possible power shortage. Large parts of the country is nevertheless anticipated to have insufficient power supplies.

Japan's power generation capacity fuelled by thermal fuels — including coal, gas and oil — is scheduled to increase by 9.5GW from a week earlier to 115GW on 3 July and further rise to 127GW on 27 July, according to data provided by the Japan Electric Power Exchange.

By Motoko Hasegawa