Every type of energy utilization for electricity generation has environmental consequences. The main consequences of burning fossil fuels and of nuclear power are well-known. Renewable energy sources (wind, solar, biomass, hydroelectric, geothermal, etc.) are generally thought of as harmless, but this doesn’t mean they have no environmental consequences at all. Most of them have a significant aesthetic impact and require large areas of land. Some also have a significant impact on the eco-system (birds, fishes, etc.). This paper summarizes the environmental issues caused by all kinds of renewable energy sources.