Energy is the keystone of all sectors of society. It is responsible for economic growth and also for the well-being of thousands of people. However, the electricity production contributes to many environmental problems and affects sustainability. The most known problem is climate change, caused by the release of greenhouse gas emissions, but there are other impacts, and this work addresses them using life cycle assessment with CML method. The shift to renewables is a response to all these challenges. The main conclusion is that there are other significant impacts such as those linked to ecotoxicity (freshwater, marine, etc.), human toxicity and material resources: metals/minerals. The evolution for Portugal along the time (2020–2050) is clearly positive for some indicators such as climate change (decrease) but others, as the ones mentioned above, show a negative trend (increase). When considering scenarios for the future, it is important to be aware that the electricity consumption is foreseen to increase along the time and that also negatively affects the results.