In order to create in Europe a greener and low-carbon economy, based on a more effective use of resources, coordinated actions between local and regional governances must be carried out according to a bottom-up, cross-level approach. In this framework energy efficiency and the promotion of renewable energy sources are two key aspects for reducing emissions, improving the security of energy supply and competitiveness as well as making energy more accessible for consumers. In recent years, feed-in tariffs and other incentives have boosted in some European countries, including Italy, the distributed generation of electricity from renewable sources requiring a reorganisation of current electric power systems from passive to active networks where "prosumers" can play a key role in balancing the electricity system (smart grids). Microgrids can be considered as the "building blocks of smart grids" which utilise local load and local microsource generation, providing a large variety of economic, technical, environmental and social benefits to different stakeholders in terms of flexibility of ownership constitution, global optimisation of power system efficiency and motivation of end-consumers (Schwaegerland Tao 2014). This paper presents the results of an ongoing research concerning a comprehensive assessment of benefits and costs that microgrids development can provide at local/regional scale. First, the role of smart grids and microgrids is discussed with reference to the latest normative regulations and scientific findings. Second, we introduce a local case study (City of Potenza, Basilicata region, Southern Italy) which has been recently under the focus of a feasibility study focusing on microgrids. Finally, the main costs and benefits (economic and environmental) associated with the proposed intervention are evaluated, discussing about their replicability in other territorial contexts and providing some lessons learnt and final conclusions.