Presidential nominee Yoon Suk-yeol of the main opposition People Power Party claimed Thursday that it was impossible to transition to 100 percent renewable energy sources, adding that traditional sources of energy must be maintained as well in working toward sustainable growth.

During a TV debate held among four major presidential candidates, Yoon said the initiative of RE100, which entails committing to use 100 percent renewable energy by 2050, is impossible to achieve, as the demand for energy cannot be sufficiently met with eco-friendly energy sources.

In response to a question from his main rival Lee Jae-myung of the ruling Democratic Party of Korea what Yoon’s opinion is on RE100, Yoon said he is unaware of the concept.

"Can you repeat what you said?” Yoon said in response to Lee's question. "Oh, that 100 percent renewable energy doesn’t make any sense."

The RE100 initiative is a global clean energy campaign led by the international nonprofit organization Climate Group aimed at curtailing global carbon emissions. South Korea launched a domestic RE100 campaign last year.

Yoon has consistently appealed during the campaign that he is pro-nuclear energy, having vowed to abolish the Moon Jae-in administration’s nuclear phase-out plans. He also vowed to reset the timeline and goals for the country's transition to carbon neutrality if he wins the election.