The Tokyo Electric Power Company (Tepco) was forced to take emergency power-cutting measures yesterday to prevent the Japanese capital plunging into blackout amid a nuclear energy shortage and a record heat wave.

As much of Japan sizzles, demand from air conditioners in the so-called “heat island” of Tokyo has soared. It has already far outstripped Tepco’s own predictions and yesterday came within a whisker of the company’s maximum output capacity.

After its closest shave in years, Tepco admitted that, for the first time since 1990, it had signed emergency deals with numerous “large lot” electricity consumers that would allow the utility to reduce supply to certain factories if a blackout appeared to be imminent.

The deals, which have been made in secret, are expected to affect hundreds of manufacturers with operations based in and around Tokyo. Nissan, the automotive giant, is understood to be among the companies that received a precautionary message from Tepco yesterday.

Tepco – reeling from the recent closure of the world’s largest nuclear power station in the northwestern town of Kashiwazaki – has taken to desperate measures in its efforts to keep the lights on in the capital.

The nuclear plant was closed down after a huge earthquake in June, which caused a series of radiation leaks as well as a fire and has left the entire area scarred by deep cracks. The discovery that the plant had been constructed directly above an active earthquake fault line has caused both Japan’s leading seismologist and its leading metallurgist to demand that it never be reopened. If those calls are heeded, it would scupper Tepco’s long-term energy supply plans.

To the horror of the Citizens’ Nuclear Information Centre, Japan’s main antinuclear group, Tepco’s supply crunch has caused it to postpone twice regular safety checks on another controversial nuclear reactor in Fukushima, about 160 miles north of Tokyo.

Energy commodity traders have reported that Tepco has come into the liquiefied natural gas and crude oil spot markets recently as a significant buyer, earmarking about 180,000 barrels a day to run conventional power plants that were, until a few weeks ago, mothballed.

Tepco has also resurrected a hydro-electric power plant in its bid to keep supply in pace with demand.

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