Unprofitable German coal-fired power plants are set to close down at a faster rate than initially expecJanschwalde coal power plantted.

Dwindling margins means a quarter of hard coal-fired generation capacity in Germany may shut ahead of schedule if plant operators forgo spending on upgrades to keep aging stations open, according to Nena AS, an Oslo-based energy consulting firm.

Bloomberg reports that Steag GmbH, the nation’s fifth-biggest power producer, is considering shuttering at least five of its 13 German coal stations before plan.

The clean-dark spread, a measure of coal-plant profitability, for next month in Germany dropped 57 percent in the past 12 months to EU2.80 per megawatt hour, a third of the five-year average for this time of year, according to broker data compiled by Bloomberg.