Given the routine electricity exchanges among power companies, the shutdown of all reactors at Chubu Electric Power Co.'s Hamaoka nuclear power plant could lead to dwindling power supplies of other regional utilities.
Tokyo Electric Power Co. (TEPCO), already facing huge electricity shortages mainly because of the crisis at the Fukushima No. 1 nuclear power plant, is counting on other utilities, including Chubu Electric, for 1 gigawatt in power supply.
But with the Hamaoka reactors offline, Chubu Electric will have no surplus power to provide to TEPCO.
"With 1 gigawatt evaporating, how are we supposed to make up for it?" asked a clearly irritated TEPCO executive.
The Kan administration, which asked Chubu Electric to shut down all Hamaoka reactors until additional anti-disaster measures are in place, will likely postpone its policy decision on supply and demand of power in eastern Japan. That decision was originally scheduled for May 10.
Although their coverage areas are separated, regional power companies exchange power under a chain-like system.
The Electric Power System Council of Japan, consisting of power providers, publishes "rough measurements" on the power transmission capacities of different providers. It acknowledges that its figures are sometimes lower than the possible maximum amounts.
According to the council, Chubu Electric's supply capacity toward TEPCO is 1.03 gigawatts.
But power supply from Chubu Electric to TEPCO must go through a special class of substations that convert the frequency from 60 Hz to 50 Hz. This currently strictly limits the potential power supply to 1.03 gigawatts.
Banri Kaieda, the minister of economy, trade and industry, has asked Kansai Electric Power Co. (KEPCO) to supply power to TEPCO in light of the shutdown of the Hamaoka reactors.
KEPCO's supply capacity toward Chubu Electric is 2.5 gigawatts, so if 1 gigawatt is passed on to TEPCO, Chubu Electric can still receive 1.5 gigawatts.
An additional 0.3 gigawatt from Hokuriku Electric Power Co. would give Chubu Electric a capacity of 27.95 gigawatts in July, 9 percent above the projected peak demand in summer.
But the mutual supply of power is contingent on the presence of surplus supply capacities, which are largely absent at utilities in western Japan.
Since May, Kyushu Electric Power Co. has been receiving 0.4 gigawatt from Chubu Electric, but the supply will be discontinued after the shutdown of the Hamaoka plant.
Kyushu Electric has no prospect when it will be able to resume operations at the No. 2 and No. 3 reactors of its Genkai nuclear plant.
Since the March 11 Great East Japan Earthquake, no reactors in Japan that were shut down for regular inspections have resumed operations.
Of the 11 nuclear reactors in Fukui Prefecture operated by KEPCO, three are out of service due to regular inspections, and three more are scheduled to undergo such inspections.
"The situation will be tough for us at KEPCO as well if we cannot bring them back to operation," an executive said.
One problem for utilities seeking to bring nuclear reactors back online is growing fears about nuclear power in communities that host nuclear plants because of the ongoing crisis in Fukushima Prefecture.
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