Another important function was the establishment of a port for the export of fertilizer from Norsk Hydro's plants in Vestfold og Telemark. The Telemark Canal had been used for transport from Notodden from the start of operations there, while a railway, Rjukanbanen, had been built to the plant in Rjukan to Notodden. In 1916 this railway was extended as the Bratsberg Line to Skien, and then to Herøya when it opened, replacing the need for the canal. Since then there has been opened other plants at Herøya, including a production plant for PVC (in 1951).