CORRECTED-S.Korea to shut 10 old coal-fired power plants by 2025

(Corrects 10th paragraph to Asia’s No.4 economy, not the world’s No.4 economy)

* Of the 10 to be shut, 2 will switch to biomass from coal in 2017

* The shutdowns should reduce fine dust levels by 24 pct by 2030

* State-run utilities to spend $8.7 bln on closure, upgradation

* South Korea will build planned 20 new coal-fired plants by 2022

By Jane Chung

SEOUL, July 6 (Reuters) - South Korea plans to shut 10 ageing coal-fired power plants by 2025, as it ramps up efforts to curb the country’s reliance on the polluting fuel and meet its pledge taken at last year’s Paris climate summit to reduce greenhouse gas emissions.

Coal accounts for 40 percent of South Korea’s electricity supplies, but the country is hoping to tilt the balance of its energy mix towards cleaner fuels to reduce pollution. In fact, Seoul recently said it was targeting $37 billion in renewable energy investment by 2020.

“In response to growing concerns over fine dusts, we will lower the share of coal power by shutting down old coal-fired power plants and restricting to add new coal-fired power plants in the future,” the energy ministry said in a statement embargoed for release on Wednesday.

The ministry expects the shutdown of the 10 old coal power plants, which have a combined capacity of 3.3 gigawatts, to lower fine dust levels by 24 percent by 2030, from 2015 levels.

State-run utilities will spend 10 trillion won ($8.68 billion) for the closure and for the upgradation of existing power plants by 2030 to lower emissions, the statement added.

Of the 10 plants that Seoul plans to retire, two will replace coal with biomass from 2017, it said.

Among the country’s remaining 43 coal power plants, eight that are more than 20-years old will be retrofitted with improved parts to curtail emissions, while the rest, operational for under 20 years, will get expanded emission-reduction facilities, the statement said.

South Korea will build 20 new coal-fired plants by 2022 as planned, but no additional plants will be considered when the government maps out its power supply plan for 2017-2031 next year, the ministry said.

This should boost the share of low-carbon and environment friendly fuels such as natural gas and renewable energy in the country’s energy mix by 2029, said an official at the ministry, who declined to be identified.

Currently, Asia’s No.4 economy generates 30 percent of its electricity from nuclear utilities and 25 percent from liquefied natural gas-fired plants.

A shift in this mix away from coal could help South Korea reduce its imports of the fuel in the long run. In the short-term, however, its demand for coal is expected to shoot up as new plants come online.

Changes in demand at the world’s fourth-biggest importer will impact global coal prices that have plunged 70 percent from their peaks in 2008 amid a persistent supply glut.