Closing coal plants to help achieve “ambitious” emissions cuts had little merit environmentally but would be economically damaging, the head of the country’s Free Democrat party (FDP), Christian Lindner, told local media on Sunday.

Closing coal plants at the same time as exiting from nuclear power “has little positive impact on the global climate”, he said during an interview with broadcaster ZDF, but stressed his party remained committed to the global Paris climate accord, which aims to prevent temperatures increasing 2C by 2030.

“I want to know from the Greens, how do you secure the energy supply, when coal is gone, how do you keep prices affordable?” Lindner added.

The Green party, is demanding the immediate closure of the country’s 20 dirtiest coal plants in hopes of bridging an eight-point gap to Germany’s 2020 target of cutting emissions by 40% over 1990 levels, according to Montelnews.com.

On Friday, Lindner had made a similar point on Twitter, where he posted a graphic from energy bourse EEX, showing the day’s power mix – heavily reliant on conventional capacity amid a lull in wind power generation – and an intraday price of EUR 61.94/MWh for the hour from 17:00 CET.

Talks to form a new government have been underway for two weeks, with climate and energy policy a key stumbling block for potential coalition partners the Greens, FDP and Angela Merkel’s Christian Democrat union.