South Korea's coal-fired power output surged nearly 15% year-on-year this year, even as the government aims to phase out coal by 2040.

Data from Korea Electric Power Corp. (KEPCO) released September 14 showed total power generation from March to July reached 242.13 TWh, a 0.3% drop from a year earlier.

Coal-fired generation, however, climbed 14.9% from 62.25 TWh to 71.53TWh. Its share of total output rose to 29.5% from 15.6%.

Nuclear generation fell 11.4% to 70.85 TWh, reducing its share to 29.3% from 32.9%. Gas-fired output also dropped 3.9%, while renewables grew 6.9%.

The International Energy Agency (IEA) now expects Korea's coal demand to increase 6% this year to 119 million tonnes, reversing an earlier forecast of a decline. It also noted that coal-fired generation rose 30% in the first quarter and coal imports are set to grow more than 10% for the year.

The sharp rise in coal use was driven in part by higher liquefied natural gas (LNG) prices after shipments through the Strait of Hormuz plummeted. Power producers shifted from more expensive gas to coal, while reduced nuclear availability added to the reliance on coal.

The IEA expects the increase in coal-fired generation to ease if idled nuclear reactors restart later this year.