Questions in regards to review electricity generation and demand data for FY 2016

Regarding Electricity generation and demand data for FY 2016, Chubu Electric Power has upwardly modified solar PV data of several hundred MWh scale. TEPCO has incorporated several thousand MWh scale corrections mainly on pumped hydro, hydro power and interconnection.

In accordance with data updated from October to December 2017, we reviewed and revised the data for FY 2016. Since the last time we had arranged the data was early December 2017, Chubu Electric Power and TEPCO did some corrections. Along with that, the results of the “data search” have changed.

As for Chubu Electric Power, the total supply of every hour has not been changed, but it seems that the data of the PV generation has been reviewed and the value of the thermal power has decreased by that amount of the PV generation. The PV generation was upwardly modified for almost a year. The biggest increment was 347 MWh increase from 4388 MWh to 4735 MWh at 12 pm om March 4th 2017.

We asked the reason for this change. Then the company responded, “it is because there was missing data etc. Also not limited to PV, the data itself is treated as a preliminary value, so there is a possibility that further corrections will be made in the future”.

Chubu Electric Power’s data page has the following description; other general electric utilities also have similar descriptions.

  • Although it is based on actual data, there are cases where estimated and statistical data are adopted from analyzing acutal situation. Therefore, data might be treated as a preliminary one. When correction is necessary, it will be fixed afterwards.

Next, the follwing four points were fixed by TEPCO.

  1. Data for pumped hydro in May was modified from -1810 to 3270 MWh
  2. Data for hydropower only in August was modified from -730 to 1640 MWh; this seems that the previous data might have been shifted by one hour.
  3. Data for interconnection lines from November was modified from -2370 to 1340 MWh.
  4. Overall supply and demand amount did not change. However, the data of thermal power generation has adjusted.

Especially for inquiries 1 and 3, the company explained “there was a difference in distribution of data aggregation, so the data was fixed”.

TEPCO released the following description on their website.

  • Power generation data include estimation.
  • Published values from the past might be corrected.
  • Please be aware that we will not notify everyone for revisions and we will not supply data before corrections when revising published figures.

We believe that modifying data will provide more accurate data. However, it is necessary to indicate when the corrections are made in the case where there is a correction in order to improve the convenience of data usage and to improve the reliability.

Basically, it is all managed as a preliminary value, so we do not know when the data is finalized. We wonder if other general electric utilities review periodically. Since there are doubts about it, it might be required to check the process in the future.