Century-Old Engineering Idea Brings Sun to Mountain Town

Friday, November 1st, 2013
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A small town in Norway is set to enjoy sunlight for the first time ever in winter due to the belated realization of an engineering concept first conceived one hundred years ago.

Rjukan, a small industrial town of less than 4,000 situated in Telemark in southern Norway, does not receive any direct sunlight from September to March as a result of its location at the bottom of the narrow Vestfjord Valley, where the reach of the sun’s rays is impeded by adjacent Gaustatoppen mountains.

The inhabitants of Rjukan are set to enjoy sunlight during the winter for the first time in the town’s history, however, following the implementation of an ingenious engineering concept which was first conceived exactly a century ago.

A set of three vast mirrors, together measuring a total of 51 square metres in area, were installed on the steep mountain slopes adjacent to Rjukan back in July via the use of helicopters at a height of 747 metres above sea level, or approximately 450 metres above the Rjukan town square.

rjukan mirror

Solspeil Mirror – Rjukan

The three mirrors – called “Solspeil,” or “sun mirrors” in Norwegian, jointly comprise a computer-driven heliostat which will direct the sun’s light onto the Rjukan town square in the form of a 600 square metre ellipse. The illumination cast upon the town square will possess 80 to 100 per cent of the intensity of the sunlight which strikes the mirrors’ surfaces.

The heliostat is not just an insert or passive installation, but comes equipped with sensors attached to a sophisticated computer system which enables the mirrors to automatically adjust to the movement of the sun. This ensures that the town square is a constant recipient of sunlight throughout the full course of the day.

“The square will become a sunny meeting place in a town otherwise in shadow,” says the official website for the project.

While this winter will mark the first time the denizens of Rjukan will be the recipients of natural sunlight, the idea of the Solspeil is almost as old as the town itself.

The town’s founder, Sam Eyde, first floated the idea of using mirrors to bring to sunlight Rjukan in 1913, realizing the lack of natural light would be major drawback for inhabitants during the winter months.

It has taken a century for engineers to make Eyde’s idea a reality, however, with Rjukan resident Martin Andersen reviving the concept in 2005 and the use of modern technology greatly enhancing the original premise.

Ryukan was built at the start of the 20th century at the behest of Sam Eyde, the founder of Norsk Hydro, as a centre for the production of fertilizer which took advantage of the nearby Rjukanfossen waterfall as a power source.

The town has since become a popular tourist destination because of its spectacular mountain views, excellent terrain for hiking and skiing, as well as the renown of the Rjukanfossen waterfall as a national landmark.

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