Current framework and future perspectives of the European electricity grid
The European power grid is the largest in the world for capacity and interconnected countries. In 2018, 902 TWh were exchanged among 34 interconnected countries through the help of 42 TSO (Transmission System Operators) [1]. There are however 5 zones within the grid, also called synchronous networks because they operate on a different frequency:
- The continental network, flowing through most of continental Europe countries.
- The Nordic network, flowing through Norway, Denmark, Sweden and Finland.
- The Baltic network, flowing through Estonia, Latvia and Lithuania.
- The British network, flowing through the UK.
- The Irish network, flowing through Ireland (and Northern Ireland) [1].
Since 2015, the capacity of all interconnectors exceeded 1 TW [2]. Due to many factors and especially the rise of intermittent renewable energy sources like wind or solar, new interconnections are built rapidly and the grid is frequently updated. Connection between the different synchronous zones have also been strengthened: between Norway and Netherlands lies the longest interconnector in the world (600km for 700MW HVDC) [2]. Indeed, Nordic countries produce a lot of energy from renewable energy sources, and benefit from exporting them to countries like Denmark, Germany or Poland to avoid curtailment. Denmark is the main bridge for transmitting electricity from the Nordic to the continental network, as it is part of both: Western Denmark is synchronised with the continental network while Eastern Denmark is synchronised with the Nordic network [2]. Because the renewable energy production from Nordic countries is likely to increase in the future, increasing interconnection will be highly profitable. If realised, the current project to create an interconnector between the UK and Norway will beat the length record, with a length of 730 km for 1.4 GW of capacity [2]. There is also a similar project to increase interconnection between Norway and Germany to 2.8 GW of capacity. Because international wind farms are being designed rapidly in the North Sea and the Baltic Sea, they will likely be linked to interconnectors too, so that neighbouring countries can benefit of their potential [2]. There is also a project to build an interconnector between France and Ireland, connecting the Irish zone to the continental zone, and projects to increase interconnection with the Baltic zone, currently synchronised with Russia and Belarus [3].
Although Europe is already quite interconnected, designing and managing interconnectors is a complex task: it involves frameworks from two different countries (sometimes more because of territorial waters), which can be complicated to associate. In that regard, supra-national organisations are needed to give guidelines, monitor processes, and plan for the long-term evolution [2]. ENTSO-E is the main organisation for the operation of the European grid, it regroups TSOs from every country. Inside countries, DSOs and TSOs are responsible for the distribution (<200kV) and transmission grids (>200kV) respectively [4]. They both have a lot of responsibilities: balancing energy and power in the transmission grid, managing congestions, maintaining the correct frequency and voltage, ensuring the security of supply and the grid infrastructure… They don’t take part in trading however, except for balancing reasons [4]. Between countries, ENTSO-E is needed as a mediator to make sure that the transmission grid operation happens correctly. ACER (Agency for Cooperation of Energy Regulators) is the organism responsible of monitoring the work of ENTSO-E: it ensures the integrity and transparency of trading in electricity markets and reviews the grid development plans from ENTSO-E [4]. These organisms play a role in the operation of the grid but also in transparency by disclosing information about electricity exchanges and grid status. In order to plan electricity exchanges correctly, information about the grid is needed, like the capacity of interconnectors or the planned production of electricity before the actual production time [2]. Transparency is also helpful for private investors: they can visualize where investments are needed and decide which projects to support [2].
International electricity trade in Europe happens differently depending on the market. In long term markets, energy trade happens via auctions from one month up to 4 years before the delivery date. Electricity is sold on bidding zones throughout Europe, who are delimited by country borders (except Sweden, Denmark, Norway and Italy who contain several bidding zones) [5]. In short time markets such as NordPool, trade happens to adjust long term trade across all Europe, one day before or on the delivery day. On the actual time of the delivery, to make sure that supply and demand stay matched during the trade, TSOs can sell and buy electricity from the balancing market [5]. Finally, if an imbalance is created within a bidding zone during the electricity trade on short time markets, the redispatching market is used to correct it by operating on the outputs of generators in the area [5]. Due to the recent rise of wind and solar energy, prediction on energy production is harder which is why the balancing and redispatching markets are very useful for late planning and reactivity [2].
The current objective set by the 2019 Clean Energy Package for All Europeans is to reach 15% interconnection before 2030 [2]. The current total interconnection capacity was 80 GW in 2020. Before 2025, 35 GW will be added to the network. Before 2040, and additional 93 GW is planned with already 43 GW in design stage [6]. Within Europe, some places are more interconnected than others: the Iberian Peninsula (Spain and Portugal) for example is only connected to the rest of Europe via 2.8 GW of interconnectors between France and Spain [2]. Other places would also benefit from more interconnection: Ireland, Great Britain, Romania and Bulgaria who are only connected via DC cables today, Greece, the South of Italy, the Baltic States who are synchronised with Belarus and Russia today [7]. This additional capacity will go towards increasing interconnection to these areas, but also towards strengthening interconnection inside the continental network: some places like France, Germany, Austria or Switzerland will become bigger electric hubs [6]. These objectives also imply overcoming a few challenges for the future interconnectors:
- Low-cost long-distance interconnectors: technological progress allows for the construction of longer interconnectors every year but exchanging electricity through them usually costs a lot of energy [2].
- Connecting asynchronous grids: it is now possible to establish interconnectors between different AC synchronous zones, for example using HVDC cables (High Voltage Direct Current) which are asynchronous. However, for distances under 650 km (for all current interconnectors), HVAC (High Voltage Alternative Current) would be preferable because investment costs are lower, but it is not asynchronous anymore [2].
- Integrating more renewables: in 2030, 45 to 60% of electricity demand is expected to be covered by renewables, which will happen mainly through the development of wind and solar farms [7]. Accommodating intermittent renewable energy requires more flexibility and reactivity inside the grid. If not done properly, less interconnected places like the Iberian Peninsula, the Baltic states, the South of Italy or Britain will encounter some issues related to the stability of supply [6]. Implementation of Heat Pumps and Electric Vehicles to decarbonize the Heating and Transport sectors will also put more pressure on the electricity grid: more interconnections and storage will be needed to stabilize it [7].
- Connecting remote resources to places of high consumption: in places such as the Greece islands or offshore farms a lot of renewable energy can be harvested. But transporting this energy to major places of energy consumption is challenging because electricity often needs to be transmitted over long distances [7].
The European grid also started to interconnect with grids outside of Europe. Since 1998, Spain is linked with Morocco via the strait of Gibraltar [1]. The current 400 kV interconnector has a capacity of 900 MW. Tunisia, Algeria and Morocco are synchronized together, and all possess important solar energy resources, which could benefit both Europe and them. The DESERTEC project was created to fulfil this goal: it aims to create more interconnections with North African countries and support the development of solar plants in North Africa [1]. This project would enable Europe and North African countries to increase the share of renewables in electricity. It would help supply match the current increase in electricity demand while creating more stability in the North African grid [2]. In the frame of this project, there are plans to connect Italy and Tunisia via the island of Sicily using a 400kV DC cable of 200km, with a capacity of 600 MW. This is very profitable for Italy because it will integrate the Italian Peninsula, currently on the edge of the European grid [2]. If interconnections increase in the future, Italy could also become an electricity hub between Europe and North Africa. Turkey is also connected to the European grid via Greece and Bulgaria [1]. It is also an observing member of ENTSO-E [8].
Recently with Covid-19, future interconnections plans had to be modified. Like many other sectors, activities had to be prioritized or deferred based on importance and feasibility. Operation of the grid was done offline by a limited number of essential workers, but in the meantime, it was also easier to develop the system: there was less inertia because many industries had to reduce their activities. Because of this, electricity exchanges between countries could also happen more easily, and proved to be important support. Microgrids (small grids able to function independently from the main grid) also gained importance [4]. Finally, as the grid is constantly being optimized to enable better communication, operation, integration of renewables and efficient use of energy, smart grid technologies are also promising and will be an important asset to reach the current objectives [9].
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] IEA (2016, November). Large-scale electricity interconnection – Technology and Prospects for Cross-Regional Networks.
https://euagenda.eu/upload/publications/untitled-69070-ea.pdf
[3] European Commission (2018, June 28th). Questions and answers on the synchronisation of the Baltic States’ electricity networks with the continental European network (CEN).
https://ec.europa.eu/commission/presscorner/detail/de/MEMO_18_4285
[4] Singh N. (2020, October 5th). The European interconnected network: case study of institutional requirements for a successful international grid interconnection. NAPSNet.
[5] Reif V, Schittekatte T. (2020, September 14th). Electricity markets in the EU. Florence School of Regulation.
https://fsr.eui.eu/electricity-markets-in-the-eu/
[6] ENTSO-E (2021, January). Completing the map – Power system needs in 2030 and 2040
[7] Commission Expert Group on electricity interconnection targets (2017, November). Towards a sustainable and integrated Europe.
[8] ENTSO-E (2019, June 5th). Statistical Factsheet 2018.
[9] Ardito L., Procaccianti G., Menga G., Morisio M. (2013, January 9th). Smart Grid Technologies in Europe: An Overview. Energies.