EirGrid is the independent electricity Transmission System Operator (TSO) for the Republic of Ireland. The Transmission System, often referred to as “The National Grid”, is a meshed network of approximately 6,500km of high voltage, 110,000 volts (110kV), 220,000 volts (220kV) and 400,000 volts (400kV), overhead lines and underground cables and over 100 transmission stations.
The system can be compared to Ireland’s motorway network – delivering power to over 100 bulk transfer points or “nodes” all over Ireland where power can be taken onwards on lower voltage, distribution system, lines to individual customers’ premises.
Power is generated by power plants and wind farms throughout the country, utilising a variety of fuel or energy sources – including gas, oil, coal, peat, hydro, wind and other sources such as biomass and landfill gas.
All of the major generating plant feed into the national grid and power is transmitted nationwide. This design ensures that power can flow freely to where it is needed and that if one power station, power line or transmission station is non-operational, whether due to a fault, for maintenance or for any other reason, there are other options or routes available. High voltages are used to reduce or minimise energy losses which would otherwise occur when transferring power over long distances in a lower voltage system. For every doubling of the transmission voltage, the amount of power wasted in the form of heat is reduced by 75%.
At the transmission stations power is transmitted from the grid, transformed into medium and low voltages, 38,000volts (38kV), 20,000volts (20kV) and 10,000volts (10kV), and diverted into the lower voltage distribution system or directly to large industrial operations. The distribution system is separately managed by the Distribution System Operator (DSO), ESB Networks and brings power directly to Ireland’s domestic, commercial and industrial customers.