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At the beginning of 1928 there were just a few small farms here and many hares, which probably gave Herøya its name. The farms have yielded to rising industry, but you still see hares skipping around what has become Norways largest industrial facility.

The men who came to clear the land on 1 February 1928 had more than wildlife to think about. The first few days were spent shoveling snow. Once the snow was cleared and the trees felled, the pace of work picked up and more people were employed; some 1,500 construction workers were at work in 1929.

By 12 May the same year, Herøya was ready to receive its first load of ammonia from Rjukan. It took a total 16 months from the first spade full of earth to the finished fertilizer factory. Soon, the first shipments of calcium nitrate – an improved form of the “Norway nitrate” – were sent overseas. The pioneer work that took place decades before in Notodden and Rjukan further up the river in Upper Telemark was now repeated in lower Telemark.

This work paved the way for the most important task ahead – to build a factory and start operating. All associated projects, like storage of materials, the canteen, even a fire station, were carried out in a provisional manner. The man in charge of the construction work was Tormod Gjestland. He had previous experience from Rjukan and was the first director of what we now call Hydro Porsgrunn.

The plants and other activities on Herøya provided a large number of jobs. There were enough applicants; it was also possible to transfer some personnel from Notodden. Throughout the 1930s, there was a building boom at Herøya and in the whole Porsgrunn area, with some families building a house for the second time.

Answer to vital questions

Hydro’s first plants were erected at Notodden and Rjukan because existing technology for transmitting large volumes of energy was limited. The electricity had to be used where it was produced. Subsequently, the limestone had to be transported to the plants and finished products transported back out.

Advances in electricity technology eventually made it possible to set up production facilities by a sea harbor. Hydro had already started buying real estate on Herøya during World War I, and when the company entered into a licence purchase agreement with IG Farben in 1927, it owned more than enough property to build the plants.

Herøya also had other advantages. Easy access to limestone deposits, clean fresh water, ideal harbor conditions with little or no ice in winter, and good opportunities to develop electricity transmission and rail transport. The connection with the inland plants was by rail and boat. Herøya was the answer to vital questions raised by Hydro’s top management.

Time to expand

In the mid-1930s, Hydro began to see opportunities for producing complex fertilizer – NPK (containing nitrogen, phosphorous and potassium). This idea was based on a discovery made by the engineer Erling Johnson at Odda Smelteverk that came to be known as the Odda process, whereby calcium phosphate is dissolved in nitric acid and further processed into fertilizer.

Test production began in 1936 and the first production of regular NPK started in 1938. Afterwards, Hydro took over patents from Johnson (1947) and developed the NPK process that is used today at Herøya – called the Hydro process. Johnson had also sold a licence to BASF, which developed what was later called the BASF process.

New products – more business areas

Fertilizer production at Herøya continued to develop, and during the 1930s, sodium nitrate (the same chemical compound as natural Chilean nitrate) was added to the product range, which also included urea and ammonium nitrate.

Later, new business areas in Hydro contributed to making Herøya the largest industrial workplace in Norway.

1928: Proximity to the market 1920: Hydro's guest houses 1919: Research as driving force and inspiration 1919: The 8-hour day