The Microgrid concept is becoming a reality since its careful design and operation could solve a variety of challenges. The massive interconnection and operation of decentralized energy resources near the loads, electric loss reductions, customized quality of electrical supply to clients, energy efficiency increase and greenhouse gas emissions reduction when electric and thermal loads are supplied by high efficiency generation units (CHP, Combined Heat and Power, or CHCP, Combined Heat, Cool and Power) or renewable energies are their major advantages. Microgrids are a common research topic in USA, Canada, Japan and Europe, where several pilot installations have been specified, designed, built and operated with some other demonstration and research facilities being planned. This paper gives an overview of definitions and evolution of the microgrid concept, the different approaches to microgrids in the three continents, specific problems solved by real microgrids and, as an example, it also analyzes the major barriers actually encountered in the Spanish legislation for their wide deployment. Finally, the role of the Energy Department of LABEIN-Tecnalia in the field of microgrids is described.
