A well-built electricity grid is a precondition for a low-emission society. The grid is needed to transport renewable power from producers to consumers, and a well-built grid is needed to exploit resources and flexibility in the best possible way. All of which is fundamental if carbon emissions are to be cut.
Through a dedicated R&D project, Statnett and its research partners have developed a pylon made out of aluminium for use at the 420 kV that flows through the Norwegian national grid. Statnett has now also performed a lifecycle analysis of the carbon footprints for various types of pylon, including those made of aluminium. The results show that the carbon emissions associated with the aluminium mast are only half those of a steel pylon. This is largely because aluminium can easily be recycled and reused. The calculations show that an aluminium pylon made in Europe produces 13 tonnes of carbon emissions, while a European steel pylon produces 23 tonnes of CO2. If the aluminium is produced in Norway, the carbon emission level is even lower.
Lighter steel pylons, called M-pylons, which are suitable for flatter terrains, also emerge well from the carbon footprint calculations. Because this type of pylon uses much less steel, its carbon emissions are reduced by half.
“At Statnett, we want to find ways to include these factors when we are deciding which type of pylon to use in connection with the construction of new power lines,” says Anreas Istad Lem, who has overseen the development of the aluminium pylon for Statnett.
The aluminium pylon is not suitable for all types of terrain, and it has not been tested to see how it copes with all the volumes of snow and ice that can accumulate on a power line. “Initially, the pylon will be tested on the stretch leading to the Kobbvatnet substation, but we are also looking at opportunities to use aluminium pylons on a planned power line between Aurland-Sogndal and the upcoming grid reinforcements at Haugalandet,” Lem explains. “The pylon we have developed is designed to cope with around 5 kg of ice and snow per metre of line. In many places, it is normal to build power lines to withstand a load of 4–5 kg per metre, but in certain places in Norway, we must also build pylons that can handle more extremes of snow and ice.”
The M-pylon, which is fixed in place using external stay cables, is best suited to slightly flatter terrain, and may be appropriate for use on certain stretches where today’s power lines are gradually going to be replaced.