The dark doldrums are a phenomenon that occurs at times when neither the wind is blowing nor the sun is shining, meaning that the production of electricity from renewable sources such as wind and solar energy is severely limited. Particularly in the winter months, such phases can last for several days or even weeks in Austria and throughout Europe. This poses considerable challenges for the energy system, as it is necessary to cover electricity demand in other ways during these periods.

For countries like Austria, which obtain a significant proportion of their electricity from renewable energy sources, the dark doldrums are a critical issue. Austria is relying heavily on wind and solar energy to achieve its ambitious climate targets and reduce the proportion of fossil fuels. However, the dependence on weather-dependent energy sources makes the system vulnerable to these weather-related fluctuations.

During a dark doldrums, other energy sources have to be activated to keep the power supply stable. Traditionally, fossil fuels such as coal and natural gas have been used here, but in order to meet climate targets, Austria is looking for more climate-friendly alternatives. One possibility is the increased use of hydropower, which plays a significant role in Austria. With around 60% of the total electricity demand covered by hydropower, it offers a reliable source of energy that can also be utilised during dark doldrums. However, capacities are also limited here, especially during dry periods.

Another solution for dark doldrums lies in storage technology. Large battery storage systems and pumped storage power plants could help to store surplus electricity from sunny and windy periods and make it available when needed. In Austria, work is already underway to expand storage technologies in order to ensure greater security of supply in the long term. Pumped storage power plants in particular, which are operated in the Alps, offer an important buffer function by storing energy and feeding it back into the grid when required.

European cooperation is also a decisive factor. In the European electricity market, countries that produce sufficient electricity from other sources during a dark doldrums can cover the demand in neighbouring countries. Austria is closely integrated into this European electricity grid and benefits from the availability of hydroelectricity from Norway or solar energy from southern Europe, for example.

Another option for bridging dark doldrums could be the increased use of biomass or geothermal energy. These energy sources are not dependent on the weather and, in a well-diversified energy mix, could help to stabilise the supply in times of crisis. However, there are challenges here too: Biomass, for example, is only available to a limited extent and the expansion of geothermal energy is not yet very advanced in Austria.

In the long term, the infrastructure must be expanded to further improve the integration of renewable energies into the electricity grid. Technologies for flexibilising demand, i.e. the ability to shift electricity consumption at times of high generation, play an important role here. Smart grids and control systems can be used to better adapt consumption to supply, which makes dark doldrums appear less dramatic.

Overall, the dark doldrums represent one of the greatest challenges for the energy transition. Austria and Europe must therefore rely on a combination of energy storage, flexible generation capacities and international cooperation in order to secure the energy supply even in times of low production from renewable energies. This is the only way to achieve the goal of a CO₂-neutral energy supply.