Omexom Breaks Ground on Sweden’s First Wooden Transformer Station in Karlshammar
On September 24, Omexom and E.ON marked a milestone in sustainable energy infrastructure with the groundbreaking of Sweden’s first transformer station primarily constructed from wood, located in Karlshammar in Mönsterås municipality.
Omexom and E.ON are investing SEK 81 million in the new facility to set an entirely new standard of sustainability and innovation for the energy industry. Replacing a 1960s substation lacking capacity and located close to the Emån River and housing, butting up against residential quarters south of the old station has both environmental connected with improved logistics.
A key feature of the project is its strong focus on reducing climate impact. Using solid wood instead of traditional concrete cuts the station’s carbon footprint by approximately 17%. The facility will also be completely free of SF₆ gas, a highly polluting insulator with a climate impact 23,500 times greater than CO₂. Additionally, the project incorporates climate-improved concrete, carbon-reduced steel, reclaimed oil, and reused components, including steel structures, busbars, electrical equipment, aluminum pipes, and concrete channels, sourced from other E.ON facilities.
A First-of-its-Kind Design
The station will house a 50 kV switchgear with two incoming lines, a busbar, and two transformers stepping voltage down to 10 kV for local distribution. The wooden building, approximately 30 by 40 meters and 9 meters tall, meets all fire and safety standards while providing full weather protection for the switchgear, unlike typical installations where some components remain exposed. This required innovative engineering, including new wall penetrations and coordination with multiple contractors.
Sustainable Innovation at Every Level
Sustainability is at the core of the Karlshammar project, with innovative and circular practices integrated throughout the design and construction.
Waste heat from transformers will be reused to heat the switchyard, improving energy efficiency. Earthworks are adapted to the natural terrain to minimize disturbance, with construction machinery powered by hydrogenated vegetable oil (HVO 100) to reduce emissions. Locally sourced rock from a nearby blast site is used in earthworks, and notably, around 40,000 beech wood nails, proposed by a subcontractor, replace steel fasteners in the wooden facade, exemplifying the project’s collaborative innovation.
These measures collectively demonstrate a strong commitment to reducing environmental impact and setting new standards for sustainable construction in the energy sector.
Gerd Karlsson, Project Manager at Omexom Substation South, shares how early involvement in the design process opened the door to more innovative thinking around sustainable solutions. “This is a groundbreaking initiative for both Omexom and E.ON,” Gerd said. “It’s by staying open to new ideas that we discover solutions that truly make a difference.”
Looking Ahead
Niklas Olsson, Electrical Designer at Omexom Sweden Substation South, responsible for the control room and 10 kV systems, emphasized that while the technical core remains familiar, the wooden construction and recycling efforts make this project truly special.
Overall, the Karlshammar substation serves as a pioneering example of how environmentally conscious engineering can drive progress in the energy industry. The station is expected to be operational by the end of 2026.