American Charles Martin Hall and Frenchman Paul Héroult independently discover an industrial method for producing aluminium. The first full-scale production facility is ready in the United States in 1888. Until then, aluminium had been very expensive. The process requires large amounts of electricity - 50 to 60 kWh per kg. In 2009 Hydro consumed an average of 13.9 kWh per kg aluminium and we are working continuously to reduce this further.

Hydro's first industrial facility - producing calcium nitrate with the company's leading-edge technology - requires a lot of electricity. In 1907, the company uses 30 000 horsepower from the power plant at Svelgfoss in Norway. At the same time the company begins construction at Rjukanfossen and the power plants Vemork (1912) and Saaheim (1915). Both were the largest in the world at the time.

Vigeland Brug starts pilot production of aluminium. Vigeland is a small business and in 1948 switches to the production of high purity (99.999 percent) aluminium. Hydro owns 50 percent of the company after acquiring VAW in 2002.

A/S Stangfjord Elektrokjemiske Fabrikker commences operation with British owners. The plant is in operation until 1945. Stangfjord was important for the future aluminium industry in Norway. Employees from here later helped to build up aluminium plants in Norway.

With a suitcase full of experience from the building of Notodden and Rjukan in Norway, Sigurd Kloumann assumes responsibility for power plants, smelters and local communities in Høyanger for NACO. The company later becomes part of ÅSV and finally Hydro. The vision is to build a green industrial city, with parks, avenues, houses and gardens, providing good living conditions for everyone. Høyanger becomes a spearhead in the development of the Norwegian welfare state.

The military rearmament during the 1930s creates a high demand for light metals. The German production increases from 33 000 tons in 1933 to 195 000 tons in 1939. VAW alone accounts for 20 percent of global aluminium production when World War II breaks out. After the war, German production starts up again in 1948 and demand for aluminium increases again sharply in the beginning of the 1950s.

Hydro establishes a research laboratory on Herøya in Porsgrunn. The lab later becomes Hydro's Research Center, Hydro's largest prior to the sale of the oil and gas business in 2007. In 2010, Hydro's Norwegian expertise center for alumina and bauxite is located here.

The Norwegian Parliament decides to build an aluminium plant in Sunndal. The operation, which starts production in 1954, is funded in part with support from the Marshall Plan.

VAW enters a period of expansion with the construction of the aluminium plant in Neuss in Germany. In 1970, Alunorf is built in the same city. Alunorf, 50 percent owned by VAW, becomes the world's largest rolling and remelting facility for aluminium. In 1973, a new rolling mill is built in Grevenbroich. The plant is expanded in 1987.

Hydro decides to build an aluminium plant at Karmøy in Norway together with the American company Harvey Aluminium. The facility is based on Søderberg technology. A rolling mill and extrusion plant are also built to process the metal further. Production starts in 1967. Hydro takes over the entire operation in 1973.

After a visit to Alcan, ÅSV invests in the new pre-bake technology Alcan is using. It is installed in the new production line being built in Sunndalsøra in Norway during 1967-69. This technology is chosen while construction of the buildings is in progress. It is the first time closed electrolysis cells with pre-baked anodes are used in the aluminium industry in Norway.

Hydro's first foreign investment in aluminium is the construction of an extrusion plant in Tønder, Denmark. The initiative also heralds Hydro's new interest in the production of aluminium profiles.

The new production line in Høyanger is the source of Hydro's proprietary electrolytic technology that is constantly improved and rolled out to the new facilities Hydro has built in recent years. HAL technology is installed in Venalum 5 in Venezuela, Slovalco in Slovakia, Sunndal 4 in Norway and Qatalum in Qatar. The newest members of the family are the test cells in Årdal.

Hydro acquires the Norwegian state-owned company ÅSV and achieves a combined annual capacity of 600 000 tonnes of primary aluminium. ÅSV, which contributes 390 000 tonnes, has a strong tradition of research and technology development that is carried forward in Hydro. The research center in Årdal specializes in electrolysis and carbon, while the research center in Sunndal concentrates on metallurgy.

With the purchase of five extrusion plants from Alcan, Hydro almost doubles its extrusion capacity and becomes Europe's largest company in this area.

Hydro acquires 25 percent of Wicona, a supplier of high quality building systems to the German market. Three years later Hydro takes over the entire company. This company, together with Domal and later Technal, forms the basis for Hydro Building Systems. About 50 percent of all aluminium profiles produced are used by the building industry.

The remelter in Holmestrand in Norway – as the first of the then Hydro facilities – receives its first shipload of post-consumer aluminium scrap to use as raw material for its production of aluminium rolled products. Recycling of aluminium requires only about 5 percent of the energy that goes into the production of primary aluminium.

Hydro contributes to the creation of the Institute for Industrial Ecology at the Norwegian University of Science and Technology. Cooperation with the university grows steadily and leads to an Industrial Ecology Program. In 1999 the program becomes interdisciplinary, combining technology, the natural sciences and the social sciences in the search for sustainable solutions for the production and consumption of energy and resources.

Production of aluminium profiles generates significant amounts of processing scrap. In 1996, Hydro acquires the Clervaux remelting plant in Luxembourg, where process scrap is melted into extrusion ingot. A remelting facility can, depending on its equipment, also take in and recycle used aluminium scrap. Hydro's remelting capacity has grown to include nine stand-alone remelting plants in 2011 with a combined annual capacity of approx. 550 000 tonnes.

VAW buys rolling mills in Germany, Italy and Spain from Reynolds. In 2000, the aluminium plant at Kurri Kurri in Australia is also acquired.

New Sunndal plant is built. The development of the new production line Su4 makes the plant Europe's largest producer of aluminium. In 2005, Sunndal produces 330 000 tonnes of extrusion ingot. Su4 is built with HAL250 technology, a refinement of Hydro's proprietary technology that meets all known Norwegian and international environmental standards. An improved version of the Sunndal technology will later be used in Qatar.

With the acquisition of German VAW, Hydro becomes a major supplier of rolled products and grows further in profile production. The acquisition leads to an increased focus on the creation of products in which aluminium's special properties can help to save energy and reduce greenhouse gas emissions.

Hydro takes over the French company Technal, a major European player in aluminium building systems, present in France, Spain, Portugal and the UK. The German company Wicona and Italian brand Domal already constitute Hydro Building Systems. Buildings represent some 40 percent of all energy consumption, and energy efficient buildings can make a big impact. Hydro offers solutions that can achieve zero-energy buildings, even in cold climates.

New Tyin power plant opens. Electricity production increases by 15 percent with no new major impact on the natural environment. The power plant produces 200 GWh more electricity a year than the old plant.

Hydro inaugurates a new aluminium recycling furnace at the Neuss plant in Germany. In 2008 a similar furnace is commissioned in the Hamburg rolling mill. Each of the recycling facilities is capable of swallowing up to 50 000 tonnes of used aluminium scrap annually, recycling the metal for its next application. In 2010 Hydro has an installed recycling capacity of 495 000 tonnes, but actually recycles approximately 260 000 tonnes of post-consumer scrap.

Hydro opens its first energy-neutral building based on aluminium solutions in Bellenberg, Germany. Measurements show that the building produces more energy than it uses.

Hydro's electrolysis process undergoes constant improvement. The company's full-scale test cells in Årdal - which represent a further development of the technology used in Qatalum and Sunndal 4 - use 12.5 kWh per kg of aluminium produced. The average consumption in Hydro is 13.79 kWh per kg.