The volume focuses on a multidisciplinary analysis that deals with technological, economical, juridical and environmental aspects linked to Renewable Energy Sources (RES) and even considers local and public acceptance, the impact on the electric system, the industrial chain and the state of the art of research in the Lombardy Region. The Report objectives are manifold.It addresses different actors in the RES development process: the private investor and financier (EAC, feed in tariffs), the regulator (EROEI indicator for sustainability, CO2 abatement costs by 2020), the local administrator (environmental section, acceptance), the producer (technologies and costs). RES development constraints, like acceptance and regulation risks, are also underlined in the Report.