The government's estimate of electricity demand for the area covered by Tokyo Electric Power Co. was based on flimsy data that was inflated by about 20 percent from actual figures compiled by the Agency for Natural Resources and Energy.
The government's estimate of electricity demand for the area covered by Tokyo Electric Power Co. was based on flimsy data that was inflated by about 20 percent from actual figures compiled by the Agency for Natural Resources and Energy.
Households in eastern Japan have been asked to conserve energy equal to up to 15 percent of the electricity consumed last summer, but the questionable data used means households have been asked to take more stringent measures than is strictly necessary.
Household energy-saving efforts, along with the government's order to large-volume electricity users to cut usage by 15 percent, have been helped by relatively cool days in July to produce considerable leeway in the electricity supply for TEPCO and Tohoku Electric Power Co. so far.
However, many companies are still struggling to cut electricity usage in line with government requests to conserve energy in areas covered by Kansai Electric Power Co. and elsewhere in western Japan.
The government will likely continue to ask households and companies to conserve as much as possible.
The electricity demand estimates issued by the Agency for Natural Resources and Energy in May stated that at 2 p.m. in midsummer, households with someone at home would use 1,200 watts of electricity. The average for all households would be 843 watts.
That estimate was based on data on last summer's peak usage submitted to the agency by TEPCO.
TEPCO officials estimated that all households would use 18 million kilowatts of electricity, out of total expected usage of 60 million kilowatts.
Those figures are considerably higher than the amount of electricity that was actually used, however.
According to an agency study into the relationship between electricity rates and usage volume, last summer's peak usage hours showed that households where someone was home used 1,000 watts, about 200 watts less than the estimate figure.
Think-tank Jyukankyo (living environment) Research Institute also conducted a study commissioned by the energy agency of electricity demand between fiscal 2004 and 2006. That study found the household average for peak summer usage was 670 watts, with the total usage by all households reaching 12 million kilowatts. However, the energy agency did not use those figures in compiling its estimate of electricity demand.
Under the agency's estimate of 1,200 watts per household, cutting 15 percent, or 180 watts, would require reduced use of air conditioning.
However, if the figure of 1,000 watts was used for electricity demand, a 15-percent reduction would have meant cutting use by 150 watts. That can be achieved by turning off lights instead of the air conditioning.
TEPCO officials said that because actual electricity usage data is only available for large-volume users, figures from the energy agency were used in drawing up various scenarios.
One official admitted that the estimates may have been higher than actual household usage.
Energy agency officials said they used TEPCO data without verifying its validity because it was all related to estimates of usage.
When the agency requested data on electricity usage, TEPCO officials insisted that data existed only for those large-volume users contracted for at least 500 kilowatts of electricity.
TEPCO estimated that total demand among small-volume users would be 25 million kilowatts at 2 p.m. in midsummer. That was calculated by estimating that all households would use 18 million kilowatts, while small-volume companies would use 7 million kilowatts.
However, even TEPCO officials realized the estimate of 18 million kilowatts for households was somewhat high, since most would not have anyone home during the day.
The energy agency used the figure and came up with the average amount likely to be used by the 19 million households served by TEPCO.
While TEPCO provided the initial figures used, in pamphlets the utility distributed to households, the source for the estimated figures was stated as the Agency for Natural Resources and Energy.
The company urged households to conserve energy while also warning that there could be problems in securing a stable supply of electricity if demand shot up due to unusually hot days.
The energy agency also drew up a picture of an average household that was far removed from reality in order to produce an exaggerated estimate of electricity usage.
Among the conditions were "60 percent of households would have someone at home at 2 p.m.," "about one-third of households have pets, requiring the use of air conditioning even when the owners were not home" and "owning an average of 2.6 air conditioners that would use 831 watts." An air conditioner of that capacity can easily cool a room of 10 to 15 tatami mats, or between 16 and 25 square meters.
The agency estimate also said the average household would have an average of "1.2 refrigerators using 268 watts," even though the largest refrigerators that can be used in homes only have the capacity to use about 100 watts.
Although electric power companies have conducted studies on electricity usage, they are very hesitant about releasing such data.
When Setagaya Ward Mayor Nobuto Hosaka asked TEPCO to release electricity consumption figures for neighborhoods rather than individual households, the company refused.
An electric power industry expert said, "They want to prevent new companies from entering the sector and do not want to provide information to households--which are their cash cows--that would allow consumers to know the actual costs of their electricity."
TEPCO has released figures for total electricity usage for this summer--all considerably lower than last summer.
This year's peak usage to date occurred on July 15, hitting 45.27 million kilowatts, which was about 20 percent lower than the highest figure for 2010.
While the usage ratio reached 93 percent of TEPCO's electricity supply on June 29, there was no day in July when the ratio exceeded 90 percent.
Demand has also been low in the area served by Tohoku Electric Power Co., with the highest ratio being 94.6 percent on July 9.
The lower electricity usage is due both to fewer days when daily highs exceeded 35 degrees in eastern Japan and to efforts by companies to conserve energy.
(This article was written by Ichiro Matsuo and Ryoma Komiyama.)