The energy world of the future

From large wind farms in the North and Baltic Seas to photovoltaic plants in Southern Germany – the way electricity is generated is changing rapidly. Not only in Germany, but throughout Europe. The European Union has set itself the target of reducing greenhouse gas emissions by 40 per cent by 2030. This is why the share of renewable energy sources in Germany’s energy demand must rise to 65 per cent. For comparative purposes: In 2017, around 36 per cent of Germany’s power demand was covered by renewable energy sources. This development poses major challenges for our power system. Renewable energy sources are not controllable and behave differently to conventional power plants, which have provided most of the electricity required until now.

The electricity production of wind energy and photovoltaic plants depends on external conditions. Transmission system operators estimate that in 2030 wind energy and photovoltaic plants will provide up to 133 gigawatt of power throughout Germany on windy and sunny days. However, the predicted load peaks at 92 gigawatt, and is considerably lower in most hours of the year. Consequently, the number of times when the supply of renewable energy clearly exceeds demand will rise. But conversely, there are also times when weather conditions are unfavourable. Then wind energy and photovoltaic plants barely feed any power into the grid. During these “dark doldrums”, the supply of power from other sources must be ensured. This is a challenge, because with the expansion of renewable energy sources and the phasing out of nuclear power and coal, more and more conventional power plants are being shut down.

The transmission system must hold this “changing energy landscape” together. Already in 2018, wind energy and photovoltaic plants together fed up to 50 gigawatt into the grid. They supply green electricity, primarily in sunny and windy regions, which often has to be transported over long distances to consumption centres. As a result of this new power generation landscape, the average distance to the consumer has quadrupled and is now around 240 kilometres. As the German transmission system was not originally designed to meet these requirements, it needs to be upgraded and expanded at numerous points. The necessary projects are described in the network development plan. These measures alone are not sufficient in the long term and our energy system reaches its limits. Then it is more and more often the case that supply clearly exceeds demand – and vice versa. In order to nonetheless be able to make full use of the amount of supply-dependent electricity available, the energy system of the future must be supplemented by seasonal storage facilities and innovative concepts such as sector coupling.