Climate mitigation policies in Europe call for an extensive build-up of renewable power, which will increase from 320 GIN in 2012 to 536 GW by 2020. The renewable expansion will mainly consist of the installation of new wind and solar power plants, which require additional transmission lines. The European Network of Transmission System Operators for Electricity estimates that 45,300 km of new or upgraded lines are necessary in the region over the next decade to accommodate the renewable power sources. Building a grid for renewables will help Europe achieve its climate goals, but other resulting environmental impacts have not yet been quantified. In this article a LCA (Life Cycle Assessment) for the transmission grid expansion is performed. The results show that the grid extension projects correspond to a total impact of 10.7 Mton CO2 eq. and 11.2 Mton Fe eq. Electricity transmission in Europe in 2020 will be more material intensive, requiring about 10% more metal inputs per kWh than today. Manufacturing processes for the production of transmission equipment are important for some impacts categories, particularly water depletion. Finally, a sensitivity analysis regarding recycling rates indicates that the results in some impact categories present great variation depending on the rates assumed. (C) 2014 Elsevier Ltd. All rights reserved.