Wonder how a village can spring up around a power plant? The story of Petäjäskosken voimalaitos is also the story of the village that grew around it. This hydroelectric plant sits on the Kemijoki River in Rovaniemi. It is about 36 kilometers southwest of the city center.
Petäjäskosken voimalaitos was Kemijoki Oy’s first power plant. It is also the second largest in terms of power. Construction took place from 1953 to 1957. At that time, the village of Petäjäinen boomed. Around 2000 people called it home. There were shops bars and schools. Petäjäskosken voimalaitos was the heart of it all.
The plant’s construction required many workers. At its peak about 2500 people worked on the site. Imatran Voima Oy designed the plant. Kai Blomstedt was the architect. Hemmo Arponen was the construction site manager.
The dam includes both earth and concrete sections. The earth dam stretches 838 meters. At its highest point it reaches 23 meters. The concrete dam is 230.5 meters long. The dam features seven floodgates.
The height difference or head is 20.5 meters. Three vertical turbines harness the river’s power. These Kaplan turbines each generate 50.7 MW. Together they produce 153 MW. Each turbine’s runner has a diameter of 6.2 meters. They spin at 100 revolutions per minute.
On average the plant generates 638 GWh of energy each year. This is with a flow rate of 830 cubic meters of water per second. The power plant’s tailrace canal extends for 3.3 kilometers.
Upgrades between 2005 and 2011 increased the plant’s capacity. It rose to 182 megawatts. Annual production reached 687 gigawatt-hours. Today Petäjäskosken voimalaitos is Kemijoki’s largest hydroelectric plant. This is measured by both power and production.
The plant’s reservoir stretches almost 19 square kilometers. It extends 18.8 kilometers long and 2.4 kilometers wide. The shoreline spans 46 kilometers. The average water level is about 62.5 meters above sea level.
Until 2016 the power plant even had its own fire brigade. They handled fire suppression rescue operations and oil spill control. They also focused on fire prevention. The power plant environment poses unique challenges in case of fire. Local knowledge was essential. Response times could be lengthy so on-site teams were critical. Most alarms involved inspections due to automatic alerts. Overheating equipment also triggered responses. Actual fires were rare.
Today Petäjäinen has changed. The population is around 200. Many jobs have moved to the city center. Residents commute to work in Rovaniemi or nearby towns. The beautiful river and Petäjävaara offer recreational opportunities. The village maintains a lighted ski trail.
Petäjäskosken voimalaitos stands as a testament to engineering. It also reminds us of the communities that formed around industry. It continues to power the region. It also offers a glimpse into the past.