Firefighters were called to an incident at Pembroke Power Station at 9.45pm last night.
Two Pembroke Dock appliances attended the scene, with smoke billowing from a building which currently is under construction to house five turbines.
A thermal imaging camera was used to locate the source of the smoke, which was a scaffolding board that had caught fire after being left inside an open-ended vessel, which had undergone heat pressure testing.
Two firefighters used breathing apparatus and a handheld fire extinguisher to enter the confined space to put out the blaze.
Damage was limited to the scaffolding board and smoke logging at the high level of the building.
Watch Manager at Pembroke Dock Fire and Rescue Station, Graeme Callan said: “The limitation of damage was due to the swift action of the contractors in calling out the fire service and of course the fact that the fire service has fully equipped experienced staff at the local station.”