Impacts of restricted transmission grid expansion

Focussing on a 2030 perspective in Germany, Ecofys examined the impacts of a delayed grid expansion for scenarios with a different mix of renewable energy technologies employed. With restricted grid expansion, more regional storage and flexible power plants need to be installed and renewable energy output have to be increasingly curtailed. The corresponding costs can be reduced if the renewable energy installations are distributed more evenly.

In the analysis, Ecofys applied a linear optimisation dispatch and investment model. The model minimises the total costs of electricity supply by optimising power generation from conventional and storage plants as well as optimising investment costs of the overall power generation mix. Investment decisions are made based on the principle of total cost minimisation.

The question addressed by this study relates to the German power system. However, Germany is an integral part of the European transmission system, so interactions with surrounding countries is an important part of the picture. This was modelled by simulating the whole system first with each country included as a copperplate i.e. perfect transmission through the country. Following this, the import and export flows were included as boundary conditions in a model of Germany that represents explicitly the regional distribution of renewable energies and the transmission capacities between different regions of Germany.