Development of interconnections in the European electricity grid
Electricity started to develop in Europe from the 19th century. From science experiments to city-scale implementation, electricity became a major source of energy for citizens. As time passed and technology progressed, people realized that building transmission lines from far away energy production places to important cities was very advantageous and this led to the development of national grids [1]. for trade purposes. The first transnational line was built in 1906, from Nancy (France) to Milan (Italy) through Switzerland [1]. After WWI, many Europeans were afraid that war could happen again and do irreversible damage to European countries. The idea of a political union between European countries was considered to revive Europe and achieve economic, technological progress together. Oskar Oliven, a German engineer, wrote a plan involving a single European electricity network at the World Power Conference in 1930 and translated it to French and English [2]. , but the possibilities of this kind of exchange were very limited: the capacity was very small, there were no organizations to operate or monitor transnational exchanges and the military tensions during the first half of the 20th century made communication very complicated [1].
After WWII, this idea seemed complicated and many of the infrastructures were heavily damaged. But the energy demand hadn’t stopped increasing even with the war: it was 50% higher in 1945 compared to [3]. Electricity network had to be rebuilt and country governments saw the opportunity of grid interconnections as a way to create European unity to avoid any further conflict in the future. This idea was also encouraged and backed up by the United States. Trade of resources and cooperation projects had to create enough interconnection between countries to make the possibility of any future war literally unfeasible [3]. To enable supply of electricity to match demand of electricity, European countries developed their grids with higher voltage lines: at first 220kV, later 400kV [1].
Due to the Cold War between 1947 and 1991, development of interconnections in Western and Eastern Europe happened separately:
- Eastern Europe’s grid development was carried by COMECON, a transnational entity created in 1949, similar to the EEC in Western Europe [3].
- Western Europe’s grid development was carried by the UCTPE (Union for the Coordination of the Production and Transport of Electric Power), created in 1951. The founding members were France, Germany, Luxembourg, Belgium, the Netherlands, Austria, Italy, and Switzerland [1]. Its first main purpose was to balance production surplus from during peaks to reduce the unnecessary consumption of other resources such as coal. Energy production information was spread between countries allowing for co-operation of the network and trade despite the different currencies and border restrictions at the time [3].
The first important interconnection was the 225kV AC line built between France and West Germany in 1946 [1]. UCTPE countries quickly achieved synchronous interconnection, and This will later become the continental synchronous grid [1]. Inside the continental grid, the liberalization of electricity supplies was implemented to simplify exports and imports, thus making it easier to shave electricity load during peak periods and react to emergency needs. This implied a lot of cooperation from load distributors in regions close to the borders but sharing information between borders enabled them to keep the system in control, independently. This cooperation system created a lot of trust between operators and encouraged further development within the continental grid [3]. Development of interconnections also happened within Eastern Europe, but East/West interconnection wasn’t progressing. The electric lines between East and West Berlin were even cut in 1952 [3]. Communication between East and West was held during the UNECE summits (United Nations Economic Commission for Europe), which encouraged East/West electricity development, but the progress of the interconnection was very limited [2]. The only country able to propagate East and West interconnection was Austria: because of its ties with Yugoslavia and Czechoslovakia (former Czech Republic and Slovakia) while being a member of UCTPE, this country was between both sides [2].
The first oil crisis in 1973 accelerated the exchanges between countries of the continental grid as countries turned to every other source of energy available. Interconnection wasn’t enough to ensure the supply of electricity, deprived of production from oil, but it proved to be very useful. Since oil was complicated to obtain due to its spiked price, countries turned to other sources for development: coal, hydropower, nuclear… This created more diversity between countries’ energy mix: the UCTPE saw the oil crisis as a profitable opportunity because those systems were now complementary and could relay the electricity supply depending on the different resources [1]. France had started opening nuclear plants from 1963 and the combination of the oil crisis and the nuclear energy program (Messmer plan) in 1973 accelerated the development of electricity through nuclear. As such, France was benefitting from very abundant and affordable electricity, which led to a lot of investment in developing interconnection. Existing connections were updated to 400 kV, and connections with the British grid happened via a 100kV DC cable in 1961. DC was chosen instead of AC because of difficulties to control the voltage of submarine cables and to ensure transmission capacity [1]. At the end of the 20th century, France had 46 transnational interconnections cables [1]. Nuclear was an important source of electricity for the continental grid: during the 1980s, nuclear accounted for approximately 1/3 of the total electricity flowing through the UCTPE network [3]. Acceleration of electricity exchanges implied more and quicker communication: radio and fax started to be used by operators [3].
After the fall of the USSR in 1991, some Eastern European countries joined the continental synchronous grid and the UCTPE: Poland, Czech Republic, Slovakia, Hungary. Romania and Bulgaria were also connected via DC lines at the beginning of the 2000s [1] to the continental grid via ex-Yugoslavian countries. Because European countries aimed to improve the quality of energy supply using different resources for different consumption areas, this was more interesting with the possibility to reach outside of their own borders. More interconnections would also prevent energy crisis and bring more stability to the network as intermittent renewable sources were integrated [4]. Another advantage was that affordable electricity could be transmitted to places where producing electricity was more expensive [4]. Energy exchanges were very profitable which led to the promotion of the European Single Market. At the time of the creation of the EU, UCTPE wasn’t eager for this kind of development: existing competition between each countries enabled low electricity prices and made it easier to ensure energy security [3]. The European Single Market was nevertheless implemented in 1992 when the EU was created, and the UCTPE was rebranded as UCTE. Since then, connection was reinforced with Romania, Bulgaria, and Greece from the beginning of the 2000s, as well as the Balkan countries, previously synchronized with the USSR [1]. Connections to the via Denmark and the British grid were also reinforced. However, there are also disadvantages of being interconnected and interdependent. One example is the incident that happened between Italy and Switzerland in September 2003: a tree was set on fire and damaged a 380 kV line. Neighbouring lines attempted to take over the load of this line, including another 380kV line between Italy and Switzerland. However, the situation took too long to fix which led the overloaded line to trip, followed by the rest of interconnectors which were unable to compensate the loss of two 380 kV lines. Italy was isolated from the continental grid and the inability to operate separately from the UCTE led to a country-wide blackout. It took 18 hours to completely reboot the electric system [3]. To avoid similar issues, better communication and better technology has been considered, using smart grids for example. In 2008, following the ambitions of integrating more renewables in the European grid, (European Network of Transmission System Operators for Electricity) was created as the entity responsible of operating all international transmissions systems in Europe. [1]. TSOs from all member states regrouped under ENTSO-E to coordinate operation, monitoring activities and plan future grid development [1]. In 2015, ENTSO-E represented 42 TSOs from 34 countries [5].
Today, the European Grid spreads through the entirety of the EU and even further. It is the largest grid in the world for capacity (902 TWh exchanged in 2018) and for interconnected countries (34) [1]. Looking back on its original objective to bring European countries together so that war would never be possible again, today’s situation shows this was largely achieved. “This shows in fact that electric power lines can carry not only electric power but a refreshing message of peace and this should be very rewarding for us all. “ (1988 UNIPEDE congress, when discussing FDR and GDR reconnexion).
Sources:
[1] Zengxun L., Yan Z., Ying W., Nan W., Chenchong G. (2020, April). Development of the interconnected power grid in Europe and suggestions for the energy internet in China. Global energy Interconnection.
https://www.sciencedirect.com/science/article/pii/S2096511720300451
[2] Kim Kyungmook (2007, December). History of Electrification in Europe. Korean Minjok Leadership Academy.
https://www.zum.de/whkmla/sp/0809/kyungmook/km2.html
[3] UCTE (2009). The 50 Year Success Story – Evolution of a European Interconnected Grid.
[4] Red Eléctrica de España (2012, September). Electricity interconnections: a step forward towards a single integrated European energy market.
https://www.ree.es/sites/default/files/electricity_interconnections_eng_2.pdf
[5] ENTSO-E (2016, May 4th). Statistical Factsheet 2015.