Security of supply in times of the energy transition

What do power grids have to do with the energy transition?

The energy transition, possibly the most comprehensive changeover in the power supply from fossil to renewable sources of energy, spans the sectors of electricity, heat, mobility and industry.

The energy transition has three main objectives:

  1. reducing CO2 emissions generated by the burning of fossil fuels and helping to meet the global 1.5°C target for curbing global warming;
  2. increasing national self-sufficiency through the use of renewable energy sources; and
  3. boosting regional added value through the use of local resources.

Austria’s entire (financial, national) electricity supply is to be converted to renewable energy by 2030. This objective presents new challenges for the domestic electricity industry, however. In future, economic and metropolitan areas will be supplied primarily by large wind power and photovoltaic plants, some of which are quite far away from consumers and only supply electricity when weather conditions are favourable. A state-of-the-art power grid must be able to coordinate and match these new production patterns, which are difficult to plan, with demand.

A key factor for the success of the energy transition – the realisation of a CO2-free electricity supply system – while maintaining security of supply is rapid, adequate expansion of the electricity grid.

In the next ten years, over €2.9 billion will have to be invested in the Austrian high-voltage grid alone (see NDP 2019). According to the ten-year network development plan (TYNDP) drawn up by the European Network of Transmission System Operators for Electricity (ENTSO-E), investments of around €150 billion in the power grid are planned throughout Europe. The more the pace of renewable energy expansion diverges from that of grid expansion, the more likely it is that security of supply will be jeopardised. In order to prevent congestion in the power grid, grid operators like APG increasingly have to intervene in the operation of the grid to stabilise it.

Bottlenecks in the power grid

Electricity per se cannot be stored in large quantities. If too much electricity is produced, the excess must be transmitted in the most appropriate manner, e.g. to a pumped storage power plant, where it can be stored in the form of potential energy. However, efficient integration of renewable energy is currently being hampered by the limited transmission capacities of the power grids. In recent years, government subsidies throughout Europe have ensured strong growth in renewable generation capacities.
  • In Germany, for example, installed capacity for all wind turbines is already in excess of 50 gigawatts (GW). To put this in context: if all German wind turbines were running at full capacity, Austrian peak power consumption could be covered about five times over. German photovoltaic systems provide roughly the same output.
  • Wind power has now become an efficient source of electricity in Austria, too. Domestic wind farms have an output of around 3,000 megawatts (MW). This corresponds to one-and-a-half times the output of all Danube power plants.

To make the best possible use of renewable power, it is necessary to expand the electricity grids. Most wind farms are in eastern Austria, but the storage power plants are in the west. Due to insufficient grid capacity, however, the full amount of power generated can only be transmitted to the storage plants to a limited extent. The exchange of power between western and eastern Austria is increasingly constrained as a result, and the physical flows can only be handled by implementing extensive contingency measures. At the end of 2017, it occurred for the first time that the existing grid was unable to absorb the quantity of electricity generated by Austrian wind farms and transport it to the pumped storage power plants. As a result, Austrian wind farms had to be taken offline and the storage power plants had to stop pumping.

Web Links

 Climate and energy strategy of the Austrian federal government (June 2018, in German only)

 The importance of the power grid for a functioning energy transition using the example of Germany (Die Welt, 14 August 2018): “Für die Energiewende schlägt die Stunde der Wahrheit” (in German only)