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Developing the Norwegian transmission system in a sustainable way

LCA analysis, Transmission lines, Statnett, Life cycle, Transmission system

5.10.2018

The owner and operator of the Norwegian transmission system, Statnett, has developed prototypes of new transmission towers. In order to assess the environmental impact of the towers, Statnett asked EFLA to calculate the ecological and carbon footprint from a life cycle perspective.

  • LCA in Norge
    Assessing the environmental impact of transmission towers in Norway from a life cycle perspective.

A strong and robust energy transmission system is essential for sustainable energy utilization. A sound transmission system is also vital in assuring transmission reliability and flexibility to meet future challenges, e.g. energy transition in the transportation sector. 

Sustainability in solutions

Statnett has developed aluminium towers and guyed M-towers to use in the Norwegian transmission system. They form part of the company's research and development activities, to identify both economical and sustainable solutions in the development of the 420 kV transmission system. To acquire more information on the environmental impacts of the different tower types, Statnett commissioned EFLA to carry out a comparative study, using the methodology of life cycle assessment (LCA).

The environmental impacts of three tower types, the current standard steel towers, aluminium towers and guyed M-towers, were compared for Norwegian conditions. All life cycle phases of the transmission towers were taken into account, i.e. from the raw material extraction and treatment to the manufacturing, transport, construction, operation, demolition and recycling after demolition. 

Recycling is key

When considering the entire life cycle, the carbon footprint of the aluminium tower was smaller than of the steel tower, and the recycling of aluminium was a key factor in the results. When metals, such as aluminium and steel, are recycled the manufacturing of virgin metals is prevented, saving both energy and resources. To better represent today's availability of scrap metal and the downgrading of metals during recycling, a so-called value-corrected substitution method was applied. This implies using the price ratio of scrap metals to virgin metals to determine the avoided environmental burden. Current world market prices indicate a higher scrap/virgin price ratio of aluminium compared to steel, largely explaining the positive outcome of the aluminium towers in this study. However, aluminium towers are not always applicable, and the next step at Statnett is to test them in various weather conditions. 

Positive outcome for M-towers

Guyed M-towers performed well when compared with Statnett's standard steel towers. The carbon footprint of the M-tower is almost half of its counterpart, mainly because of their lighter structure and therefore less steel needed for their manufacturing. Guyed M towers are, however, not always suitable in mountain terrain but can be applied in flatter landscape.

The LCA study carried out by EFLA also highlighted environmental hot spots for each tower type, that is target areas for improvements. Statnett now has reliable information on environmental impacts of its tower structures. The information can be used for future decision making when the Norwegian transmission system is being developed as well as supporting the development of environmental criteria for the procurement of new towers.

News articles from Norwegian websites

More information on carbon footprint and LCA calculations at EFLA