A mesh of these circuits covers the whole of Europe, generally operating at voltages between 220kV and 400kV. A single circuit at the highest voltage can typically carry about 1.3GW of power. The density of the transmission mesh is highest in regions where there are large concentrations of industry or population and is at its lowest in more rural regions. As with a road network, the more alternative ways there are to get from A to B, the more easily the traffic flows. With electricity networks, additional circuits mean greater security, as power flows can be rerouted to compensate for technical faults that take particular circuits out of use.
Apart from transmitting electricity from generators to consumers, transmission networks perform another vital function. They ensure that costs to the consumer are kept as low as possible because they can achieve high security, low production costs, flexible response times and centralised control during system disturbances. Irrespective of the amount of wind energy in Europe, therefore, closer integration of the electricity networks will be beneficial to consumers, as "big is beautiful".
Connections between the national systems in Europe have gradually been augmented over the years, but differences still exist. Austria, for example, has 47 circuits, linking it to Switzerland, the Czech Republic, Germany, Italy and elsewhere. The total capacity of these links is over 15GW, which is similar to the total capacity of all the generating plants in the country. Spain, by contrast, has a generating capacity four times larger than Austria, and only 16 circuits linking it to France and Portugal, with a total capacity of around 7GW. Britain, by virtue of its island status, is linked to mainland Europe by only two circuits, which total 2GW.
At present, coordination at the European level is organised by the European Network of Transmission System Operators for Electricity (ENTSO-E), which is studying the prospects for further integration. As the amount of wind energy on European networks grows, the advantages of a truly integrated system will become more marked.
This piece is part of the 'Diversity smooths demand fluctuations' feature