The shutdown comes after the government said last month it would idle up as much as 15 coal-fired power plants between December and February, while its remaining plants are expected to supply sufficient power.
In a statement late Monday, the energy ministry said 41 coal-fired power plants would operate at 80% capacity.
South Korea, Asia’s fourth-largest economy, operates about 60 coal-fired power plants, generating about 40% of its electricity.
Nuclear power makes up about 30% of South Korea’s electricity, followed by gas power at around 20%. Analysts expected the reduced coal power to give a slight boost to the country’s LNG demand.