In Europe, numerous forms of energy self-sufficiency or small technical systems exist, are promoted and discussed. They share the ambition to reduce the dependence to inherited/incumbent large technical systems in various sectors (energy and water supply, sanitation, waste management...) through the implementation of “local” energy systems and “small” grids. The contemporary energy and environmental crisis could rush the end of large technical systems (networks and infrastructures) as they have been developed since the late 19th century. This book examines the various options to transition.