Ahead of preliminary coalition talks this week over a new federal government, Germany’s Greens are insisting on the closure of the country’s most polluting coal and lignite plants as start of a binding coal exit – a demand that if put into practice could help renewables expansion in Europe’s largest economy.

But it could also wreck the coalition talks.

Chancellor Angela Merkel, with her Christian Democrats (CDU) and their Bavarian sister party, the Christian Social Union (CSU), on Wednesday are scheduled to first hold exploratory talks with the pro-business Free Democrats (FDP), and later with the Greens.