Life Cycle Assessment of typical projects of the distribution power network : Assessment, Improvement & Recommendations

Abstract: The carbon footprint of the power generation is studied for more than 30 years now. In order to curb GHG emissions, politics, industrials and consumers tend to take action to reduce the carbon intensity of the electricity mix, spread electrification and enhance usage efficiency. However, little is known on the growing power network which connect production and consumption. This study assesses the GHG emission of typical distribution infrastructure projects, in Sweden, with the aim to express recommendation to further improvements. The life cycle assessment (LCA) follows the Greenhouse gas protocol, gathering every related emission from the material mining till the endof-life. The computation is carried out thanks to the project data, environmental product declaration and environmental agencies carbon emission factor. In addition, 50% load hypothesis have been assumed to model the electric usage of transformer and cable. As a result, the installation of 1km of 240mm2 aluminium cable emits 35.67t CO2eq throughout its 30 years of lifespan, involving material, vehicle, and usage related emissions. The GHG sources are almost evenly split between the losses in the cable and the cable material. This total rises up to 41.81 t CO2eq, when excavation is required. The same life cycle assessment is carried out for a 30 to 130 kV substation with a transformer capacity of 63MVA. 1287 t CO2eq are accounted with the highest share coming from SF6 leakage, with 31% of the emissions. To go further, a wide range of options is studied to reduce the projects’ climate impact: going from more sustainable materials, recycling, equipment lifespan extension, more efficient devices, and alternative fuels. Climate-economic studies applied to the previous project measures the costs and benefits for each solution. It demonstrates the relevance of circular economy, even in a business perspective. The transformer refurbishment must be prioritized as it saves the most emissions and costs. The aluminium recycling must be aimed for, because of its major GHG emission reduction for (aluminium) cable project. The substation design must ban as much as possible the SF6 usage and reduce the ground surface on grassland or forest. Lastly, electrification of the fleet and green concrete help to save extra tonnes of CO2eq for reasonable prices.