It was difficult to maintain a steady light with an unprotected coal-burning beacon. Wind and poor weather effected the flames and increased the coal consumption. In 1776, the Twin Lighthouses at Lindesnes and Markøy combined had an annual coal consumption of 250 tons.
In Europe, attempts were made to place coal-burning baskets inside lantern houses. Following Paul Løwenørn’s drawings, a beacon like this was placed at Fakkebjerg, the Southern part of Fyn, in 1806. Coal consumption was significantly reduced, and it was easier to maintain a steady flame with the new enclosed system.
In 1822, Løvenørn’s drawings were used when the two enclosed coal-burning beacons were raised at Lindesnes and Markøy.
The coal-burning beacons had two floors. The first floor had 6 large air vents facing out in all directions. They were formed as funnels, and towards the centre, the small openings could be opened or shut depending on wind directions and -strength.
The air escaped up through the centre of the tower and supplied the coal-burning fire with oxygen, producing more light at a far lower coal consumption level. The movable flap in every air vent made it possible for the fire keepers to regulate the amount of air passing through.
The lantern houses must have been very warm and full of smoke at times. It is said that the lighthouse keepers would faint from the coal exhaust. That is perhaps why the lighthouse inspector had to keep a signal cannon at Selhovden.
The two enclosed coal-burning lights at “the Naize” were some of the last of their kind to be built. The year after they were lit, in 1823, the first lighthouse lens was in place at The Cordouan Lighthouse in France. In 1832, the first lighthouse lens in Norway was in use at the Oksøy Lighthouse.
The coal-burning era was not yet over. In 1839, the last «new» coal-burning Lighthouse was lit at Villa in North-Trøndelag. At this remote station, using coal seemed safer than using oil. In 1859, the Villa Lighthouse was transformed into a lighthouse with a lens and an oil-burning lantern.