Using its own technology for electric microgrids

The Public University of Navarre (UPNA) and CENER (National Centre for Renewable Energy) are taking part in a joint research project on renewable energy and based on electricity microgrids which enable enhancing energy efficiency, reducing contaminant emissions, increasing safety in supply and minimising electricity losses. The project is co-financed by the Government of Navarre, and by the European Union through its FEDER Funds.

The project, known as "Design, development and implementation of microgrids in Navarre", aims to generate technology and knowledge in the field of generated energy supply and microgrids, which will subsequently enable their transfer to the industrial infrastructure in Navarre. Two electricity microgrids have already been thus installed: one, at the CENER Head Office on the Rocaforte industrial estate in Sangüesa, Navarre; the other is on the Arrosadia Campus of the UPNA.

Microgrids are defined as a series of electrical loads, elements of generated power supply (wind, photovoltaic, fuel cell, microturbine, etc.) and storage elements (batteries, hydrogen, inertia wheel, compressed air, supercondensers, etc.) which, connected to the electric grid by means of a single point of connection, are all linked through a strategy which manages both the flow of energy within the grid as well as the interchange of power with the general supply grid. In this way, microgrids with single family dwellings, offices, industrial estates, blocks of flats, neighbourhoods or even cities can be established.

Of the two microgrids in the project, that of the UPNA, located at the Renewable Energy Laboratory of its Department of Electrical and Electronic Engineering, is aimed at generic applications and enables emulating and managing various profiles for power generation and consumption, such as single family dwellings, office buildings and small industries. It also includes the capacity to manage, in a co-ordinated manner, thermal systems that normally exist in these types of applications (heating, refrigeration and hot running water), thus forming, in the widest sense, an electrothermal microgrid. Its maximum renewable generated power is 20 kW, obtained from a wind-powered source (a wind turbine) and another photovoltaic one. Involving generator elements that can be managed, it has a 25 kW power generating set and a 5 kW fuel cell system. As regards storage, it has a 72 kWh bank of batteries, a 35.2 Nm3 hydrogen storage system and a bank of 83 F and 194 V supercondensers. Moreover, it has a programmable electronic load that enables the scale reproduction of any consumption profile.

The CENER microgrid is located at the Wind Turbine Test Laboratory (LEA) and is aimed at industrial applications, supplying part of the electric loads of the LEA installations themselves, as well as of part of the public street lighting of this industrial estate in Sangüesa (Navarre). This microgrid boasts a representative selection of power generation, both from renewable sources (notably a roof-installed photovoltaic field and a wind turbine with 25 kW and 20 kW powers respectively), as well as systems of conventional generation, including a 48 kW diesel generator and a 30 kW gas microturbine.

Both installations have great flexibility from the conception and design phase to its launching and coming on-stream, enabling them to operate in different ways and under different settings and thus meet the demands of a top-level test bank. Also notable are the advanced systems of monitoring and control that have been developed, data gathering and registering for each and every one of the relevant electric means at the installations and which, in accord with the corresponding management algorithms, govern and supervise each one of the subsystems making up the microgrids (generation, storage and consumption). In this way they manage to establish a balance between energy generated and energy consumed, as well as the co-ordinated and efficient operation of the microgrids, whether operating connected to the electricity grid or in isolated mode.

The target of both installations is, effectively, to demonstrate the viability of microgrids as a comprehensive, integrated means of energy supply, both for industrial and residential environments, as well as serving as a test bank and laboratory for related technologies. Likewise, it will be possible to draw important conclusions enabling progress to be made in the definition of the standards and procedures for the operation of and communication between the bodies involved in the supply of grid electric energy, as well as defining the needs demanded by the incorporation and integration of these microgrids.