A new chemical method to produce nitrogen based artificial fertilizers was developed by Norwegian chemist Kristian Birkeland. The method required strong electrical current and voltage. The company, Norsk hydro-elekrisk Kvælstofaktieselskab (Norwegian hydro-electric nitrogen limited) was founded in 1905 to utilize the new process. To generate power, Norsk Hydro constructed hydro plants at waterfalls.
In 1911, the company opened their second hydro plant at the Rjukanfossen, a 104-metre (341-feet) tall waterfall. The establishment of the plant enabled the founding of the town of Rjukan. Soon about 12,000 laborers from Denmark, Finland, and Sweden, plus the Norwegian workforce, inhabited Rjukan to work in the nitrogen-saltpetre manufacturing facilities.
Norsk Hydro constructed the world’s largest hydro-generating plant (at the time) in 1934 at the falls. The new plant was built in conjunction with a hydrogen factory. It was later determined by Nobel Prize winner, Odd Hassel, that the machinery was producing “heavy water” as a by-product of hydrogen production. Heavy water was important as a component of early nuclear energy research. It is still used in some types of reactors.
Norsk Hydro was taken over by the Nazi Germany occupation forces in World War Two. Hence, the Rjukan plant was the target of sabotage by the Norwegian underground resistance and allied military.
During the 1960s, fertilizer production was phased out of Rjukan and transferred to another Norsk Hydro plant elsewhere in Norway. Town leaders then worked to expand the tourism industry for the area. The waterfall is a famous landmark, and the surrounding mountains are popular for skiers and hikers.
Because Rjukan was built at the bottom of a deep valley, the town does not receive natural, direct sunshine between September and March. Tall mountains surround Rjukan and block direct sunlight from reaching the residents. Back in the day, Norsk Hydro engineer, Sam Eyde, worried that his workers were not getting enough healthy exposure to sunlight during the winter months.
One of his employees suggested that mirrors be placed atop one of the mountains to reflect sunlight into the town. The technology, at the time, was not practical nor even available for the project. To help the town’s residents, the company, instead, constructed a cable car to bring people to the top of a mountain for their rations of sunlight.
The idea of reflecting sunlight into Rjukan didn’t entirely go away. Town leaders found out that a small Italian village experienced the same problem because of its location in a deep valley. The people of Viganella had successfully implemented a series of mirrors to bring direct light into view. Rjukan sent a delegation to Italy, in 2006, to study the technology and its impact on the villagers. After five years of discussion, the Rjukan council decided to build the mirror complex of their own.
The design includes three very large mirror panels attached to moveable mounts that track solar movement to align reflected light towards Rjukan’s town center. The result is a large patch of light that people can easily access.
The heliostatic mirrors mimick the natural movement of sunflowers through mechanical means. Sensors detect the path of the sun and feed the data to a computer that determines the necessary angles to reflect the light to town. The power for the servo-motors and computer is provided by solar and wind power. There is also equipment to automatically wash the mirrors when needed.
The heliostatic system was hoisted into place by helicopter last summer. The mechanisms and guidance were tested for accuracy and reliability. On October 30, 2013, the mirror system was unveiled and activated. About 1,000 residents were present near the main square as the patch of light appeared. Celebrants enjoyed games of beach volleyball. Other folks simply enjoyed the new sunshine in lounge chairs while sporting their sunglasses.