When Karlshamnsverket was planned and built, demand for electricity in Sweden was steadily rising. Given this, in the middle of construction of Öresundsverket in Malmö in 1956, Sydsvenska Kraftaktiebolaget (now Sydkraft) decided to plan for additional expansion of its production. The choice was between thermal power (coal- or oil-burning power plants) and nuclear power, since there were limited opportunities for building new hydropower plants. The choice fell on an oil-burning plant, but immediately after the decision was made to build Karlshamnsverket, plans also began for building Sweden’s nuclear power plants.
The estimated service life when the power plant was built was 3,000 hours/year (a year has a total of 8,760 hours). The power plant was intended as a complement to nuclear power and would produce electricity when most needed, meaning primarily on weekdays and only rarely on weekends, evenings and nights. But that never happened. During the first year there was significant need for electricity in Sweden and right from the start, Karlshamnsverket produced more electricity than originally intended.