History

In 1905 the Norwegian-German partnership of Sam Eyde and Kristian Birkeland demonstrated that electric arc technology could fix nitrogen directly from the air. Norsk Hydro was founded the same year to scale this process industrially, and chose the Rjukan valley because the Vestfjord waterfall offered sufficient hydraulic head. The Vemork plant opened in 1911 and at once was the world’s largest power station, feeding an electrolysis hall where atmospheric nitrogen was converted into nitric acid and then into calcium nitrate fertilizer. Almost overnight, synthetic fertilizer became available to farmers across the globe — one of the decisive events in the demographic transition of the 20th century.

In the 1930s Vemork added a heavy water production unit as a by-product of its hydrogen generation process. By 1940, German forces had occupied Norway and recognised Vemork as Europe’s only significant source of deuterium oxide, then believed essential for building a nuclear reactor as part of their Uranprojekt (atomic weapons programme). The Allies launched three operations to deny Germany this resource. The first (Operation Freshman, November 1942) ended in disaster when two British gliders crashed in a snowstorm. The second, Operation Gunnerside (February 1943), succeeded: nine Norwegian SOE-trained saboteurs skied through the winter mountain plateau, descended the cliff face above the plant, and destroyed the electrolysis cells without firing a single shot. A subsequent USAAF bombing raid in November 1943 prompted the Germans to order the remaining heavy water evacuated to Germany. In February 1944, Norwegian resistance fighters sank the rail ferry SF Hydro on Lake Tinnsja, sending the last shipment of heavy water to the bottom — definitively ending the German nuclear programme’s access to Norwegian resources.

After the war Vemork was converted to a conventional hydroelectric station. It closed in 1971 and is now the Norwegian Industrial Workers Museum (Norsk Industriarbeidermuseum). The broader industrial landscape was preserved and submitted for UNESCO inscription, which was awarded in 2015 under criteria ii and iv.