The temporary stacks being introduced at the Kusile coal power station, where three previously operational units have been out of service for ten months, have been built and interim CEO Calib Cassim has expressed optimism that the units could be returned to service earlier than previously indicated. All three units, which have a combined capacity of 2 100 MW, became inoperable after the Unit 1 flue duct collapsed on October 23 due to a build-up of slurry. The collapse also compromised the unit 2 and 3 flue ducts, which share a common chimney with the Unit 1 flue.