Tokyo and surrounding areas face a large shortfall in electricity this summer and blackouts could become more frequent and widespread, Tokyo Electric Power (TEPCO) warned on Friday.
Japan enjoyed one of the most reliable electricity supplies in the world until 11 March, when a magnitude 9.0 earthquake knocked out several power stations. In the wake of the temblor TEPCO began an unprecedented series of planned blackouts to deal with the drop in electricity output. The quake cut the company's generating capacity by about a third, to 31 gigawatts (GW).
The scheduled blackouts see entire neighbourhoods in areas surrounding Tokyo lose their power for up to three hours to prevent the supply system from being overloaded. They are scheduled each day from morning until evening, although in recent days have only been required in the evening when demand is highest.
The blackouts have already disrupted production at factories and offices of major Japanese electronics vendors. An expansion could further delay the return of such companies to normal operations.
The amount of electricity available to east Japan is slowly increasing as power stations come back online, but it could be months before some of the power stations recover. The stricken Fukushima Daiichi nuclear power plant, which was generating 2GW when the quake hit, is likely to never produce electricity again.
As the weather gets warmer and evenings get longer, demand should fall because less heat and light is needed, but that decline is only expected to continue up to a point. When the summer begins and temperatures start climbing, Tokyoites typically switch on air conditioners.
Demand this summer is expected to be between 55GW and 60GW, but TEPCO predicts it will only be able to generate 45GW of electricity.
The government said Friday it plans to work out a number of measures that would help reduce power demand. They could include increases in the price of electricity, offering longer holidays to workers and the introduction of daylight saving time. Japan last used daylight saving time when it was under US occupation after World War II.
Homes and businesses across Tokyo have already implemented a number of energy-saving measures. Tokyo's famous neon signs and public displays have been switched off, shops are closing early, movie theatres are closed and the frequency of train services has been reduced. Japan's professional baseball league said it would halt night games through April.
The measures are paying off.
On Friday, power demand was 34GW at 4pm local time against TEPCO's capacity of 37.5GW. At the same time last year, demand was over 40GW.