The main aim of Renewable Energies is to provide an overview of the environmental impact of the different renewable energy systems, enabling readers to understand the environmental impact of electricity production, through the analysis of different generation sources over their life cycle. This means the book covers the real impact of each source of electrical generation from the extraction of materials to permit completion of the installation (solar panels, wind turbines, etc.), until finally (once the productive lifespan of the facility is over) it is dismantled and its components are sent to a landfill, recycled, reused, etc. This analysis uses the technique of life cycle assessment (LCA), allows the authors to obtain graphically and numerically the different impacts associated with each facility. It permits comparison of the different systems studied, showing the environmental advantages and disadvantages of each one of these systems. Furthermore, these systems of power generation from renewable sources can be compared to traditional systems of electrical power (fossil fuels, hydraulic, nuclear) giving a fairer evaluation, in terms of financial and environmental cost, of each one of these systems.