[News Terms] Winter Electricity Demand Hits Record High... What is the 'Supply Reserve Rate'?

On the 12th, officials are checking the power supply status at the Power System Operation Center of the Power Management Department, Gyeonggi Regional Headquarters, Korea Electric Power Corporation in Suwon-si, Gyeonggi-do.
[Image source=Yonhap News]

[Asia Economy Reporter Jo In-kyung] Domestic electricity demand has reached its highest winter level as a severe cold wave with wind chills dropping to minus 20 degrees Celsius continues and solar power utilization decreases due to heavy snowfall in the west coast region. Following the lifting of social distancing measures, industrial and general electricity demand has increased, with last summer's electricity trading volume already setting an all-time high. There are even forecasts that the peak winter electricity demand could surpass this record.

According to the Korea Power Exchange on the 20th, the maximum domestic power demand on the previous day was 91,710 MW (megawatts), the highest ever recorded in winter. This figure is 1,002 MW higher than the previous winter peak of 90,708 MW recorded on December 27 last year.

Maximum power demand refers to the moment during the day when electricity consumption is at its highest. This winter's peak demand rose to the 80,000 MW range (82,117 MW) on the 30th of last month when the lowest temperature dropped below freezing, then surpassed 90,000 MW (90,128 MW) on the 14th of this month, about two weeks later, and broke the winter record again just five days after that.

As of the 19th, the power supply reserve was 12,118 MW, and the reserve margin was 13.2%. Experts say that to ensure stable power supply, the reserve capacity should exceed 10,000 MW and the reserve margin should be above 10% to prepare for emergencies such as generator failures.

The supply reserve is the amount of power supply capacity remaining after subtracting the maximum power demand of the day. If the supply reserve falls below 5,500 MW, a power supply emergency alert is issued; however, no such alert has been issued since August 2013.

The reserve margin is the ratio of the supply reserve to the maximum power demand. The lower the reserve margin, the greater the concern about power supply stability. Until early this month, the weekday reserve margin was around 16-17%, but last week it dropped to the low 11% range on some weekdays and recorded 13.2% on the 19th.

The Power Exchange forecasts that due to frequent snowfall and cold waves nationwide through this week, the maximum power demand will reach between 87,500 MW and 92,300 MW. The reserve margin is expected to range from 12.5% to 20.5%. The Ministry of Trade, Industry and Energy announced on the 30th of last month the 'Winter Power Supply Outlook and Measures,' projecting the peak power demand for this winter to be in the third week of January, with maximum demand between 90,400 MW and 94,000 MW. This is similar to or slightly higher than last year's peak (90,708 MW on December 27, 2021) and this summer's peak demand of 92,990 MW (July 7).

A representative from the Power Exchange stated, "We predict no major difficulties in power supply this winter, but to prepare for any contingencies, we will thoroughly check additional reserve resources and actively promote power demand reduction measures centered on public institutions to ensure that the public experiences no inconvenience in electricity use."