Major Spanish utility Iberdrola is to replace its two remaining coal-fired power plants with renewable facilities.
An application for the "orderly phase out" of the firm's Lada and Velilla plants was made in 2017, with the Spanish government expected to announce its ruling next year.
In a statement Monday, Iberdrola said it intended to replace the coal-fired plants, which have a combined capacity of 874 megawatts (MW), with 500 MW of wind and solar.
Speaking to CNBC's "Squawk Box Europe" on Monday, Iberdrola CEO and Chairman Ignacio Galan said there were technologies which allowed electricity generated with fossil fuels to be generated with renewables.
Galan was speaking to CNBC on the first day of the COP25 climate summit in Madrid. He sought to emphasize the importance of the COP21 summit, which took place in Paris in 2015.
It was at COP21 that world leaders committed to make sure global warming stayed "well below" 2 degrees Celsius above pre-industrial levels. They also agreed to "pursue efforts" to limit the temperature rise to 1.5 degrees Celsius.
"Paris was for me, a step forward, very important," Galan said. "Because before Paris there were very many people who were denying that the climate … is a problem."
While the Paris Agreement has been hailed as a landmark, it suffered a blow on November 4 when the U.S. Secretary of State, Mike Pompeo, officially announced that the country had started the process to withdraw.
"Per the terms of the Agreement, the United States submitted formal notification of its withdrawal to the United Nations," he said in a statement. "The withdrawal will take effect one year from delivery of the notification."
On Saturday, the State Department said the U.S. would "continue to participate in ongoing climate change negotiations and meetings" like COP25 "to ensure a level playing field that protects U.S. interests."
Speaking about his firm's operations in the U.S., Galan sought to strike a positive tone. "Almost all our production, all our generation, is renewables in the country," he said.
"But I think the United States, the energy policy (is) certified by states, I think in most of the states they have already very ambitious targets of emissions reduction, very ambitious targets of implementation of renewables," he explained, adding that this was the case on both the east and west coasts.
Galan said Iberdrola had a presence in 23 states. "In all those states, renewables are welcome," he added.