South Korea's power generating capacity is expected to surpass the 100 gigawatt mark this year as the country moves to put more nuclear and thermal power plants online in the coming months, industry sources said Monday.

The total is expected to hit 108.7 gigawatts this year, marking an 11.3 percent gain from the installed generating capacity of 97.6

gigawatts tallied for late 2015, according to the sources.   

This year's increase of more than 10 gigawatts will mark the sharpest annual growth in terms of power capacity for Asia's fourth-largest economy. From 2005-2015, power output grew at an annual average rate of 3.5 gigawatts.

Last year, thermal power plants that used liquefied natural gas(LNG) as the source of fuel generated 33 percent of all power output at 32.2 gigawatts, followed by coal-fired plants that made up little over 28 percent or 27.3 gigawatts.

Nuclear power added 21.7 gigawatts or 22.2 percent of power output for the country, with renewable energy making up 7.6 percent and 7.4 gigawatts.

According to government plans, the Shin-Kori No. 3 reactor capable of generating 1.4 gigawatts will go online in April with two coal-fired thermal power generation units in Dangjin and two others in nearby Taean to start generating power. The combined output of the new power generation units in Danjin and Taean on the west coast will reach 4 gigawatts.

Industry insiders said that while growth in power output is a positive development, the country's growing reliance on fossil fuel is worrisome, as other countries are trying to reduce greenhouse gas emissions which are cited for causing global warming.

Coal is a cheap source of power generation but it releases 2.2 times more greenhouse gas into the atmosphere than LNG.

"The country's dependence on coal-fired thermal plants is due to actions taken by the government following the 2011 limited blackout shock," a business insider said.

He, however, said that because it takes such a long time to build power generation plants it is very hard for policymakers companies to predict energy demand trends down the line. Last year, South Korea actually had excess capacity.

The insider said that with demand not rising as fast as expected, and with LNG becoming cheaper, the country needs to follow what other countries are doing to meet electricity demands.

The United States has already said LNG will make up 60 percent of its power generation needs by 2035, with China pledging to reduce its dependence on coal. Britain has said it will halt all coal-based power generation by 2025. (Yonhap)