Scientific abstract:

A key to mitigating climate change is the reduction of our dependence on fossil fuels by transitioning to cleaner, renewable energy sources. However, the foundation of a sustainable energy system is its electricity grid. Today, about 80 million kilometers of power lines cross countries and continents worldwide to provide us with electricity. The current electricity network must inevitably expand within the next decades: new transmission lines will link new renewable power plants to the local grid, while additional distribution lines will ensure the delivery of stable and reliable electricity to consumers. Yet power lines act as a physical barrier for bird species: around the globe, hundreds of millions of birds are killed annually by power lines due to collision and electrocution. Life cycle assessment (LCA) is a suitable framework to provide a holistic view of the environmental impacts of energy systems. Indeed, life cycle impact assessment (LCIA) models were recently developed to evaluate the impacts of hydropower and wind power on biodiversity. However, these models assess only the effects of electricity production, overlooking the impacts of electricity transmission. Furthermore, current LCA studies on power lines focus on certain impact categories, neglecting the potential damage to ecosystem quality. We present the first LCIA models to quantify the impacts of electricity transmission on birds. Our models produce maps of the potentially disappeared fraction of species (PDF), which predict the risks of collision and electrocution on a large scale. These maps show how these impacts vary spatially, identify susceptible bird species, and indicate how efficient electricity transmission is across different areas. To validate the methodology, we applied them to the energy system of Norway. The majority of Norway’s energy system is based on electricity from renewable sources, and the country leads a low-emission energy policy that aims to reduce its emission by half before 2030. Overall, the characterisation factors ranged between 3.9 x 10-15 and 8.4 x 10-16 (PDF*yr/kWh) for collision and 1.9 x 10-16 and 6.5 x 10-16 (PDF*yr/kWh) for electrocution. Gallinaceous birds, waterfowl, and waterbirds were the most susceptible to colliding with power lines, and electrocution posed a greater threat to raptors, owls, and corvids. Transmission lines had higher collision impacts in densely populated areas in southern Norway, while the electrocution effects of distribution lines were greater in northern Norway. Our models are not limited to Norway. By obtaining appropriate input data, they can be applied to any region. The integration of these models in LCA is essential, not only because they introduce two new impact pathways but because they take us a step further in assessing the impacts of energy systems in a holistic way: addressing both the effects of the production and transmission of our electricity on biodiversity.