Impacts of different European renewable expansion strategies on the future demand for flexibility options like storage and transmission grid

In recent years, many energy scenario studies have proven that a power supply system based on renewable energies (RE) >90 percent is feasible. However, existing scenarios differ significantly in the composition of generation technologies. Some scenarios focus on wind energy in the northern part of Europe, others base on a large utilisation of solar technologies in the south. Apart from the generation capacities, the needed technical flexibilisation strategies such as grid extension, demand flexibilisation and energy storage are generally known and considered in many scenarios. Yet, the impact of different renewable generation strategies on the local utilisation of flexibility options needs to be further assessed. Based upon the BMBF research project RESTORE2050, analyses have been carried out that focus on these interdependencies. The results of the project show that the local utilisation of flexibilisation options depends to a great extent on the technology focus of the long-term renewable expansion strategy. This applies for the spatial flexibilisation as provided by transnational interconnection capacities, especially the ones connecting regions with a surplus of power generation (e.g. GB, Norway and Spain). Another impact of the renewable scenario is seen on the required temporal flexibilisation of electricity generation and demand. In addition, the available options will compete for high utilisation in a future energy system. The differences in the utilisation of these applications, which base on the varying shares of photovoltaic (PV) and wind energy generation, lead to the conclusion that the decision about longterm RE expansion ought to be made very soon in order to avoid inefficient flexibility pathways. Otherwise, if the future RE structure will be kept open, adequate adoption of new flexibility options will be difficult, especially in case of technologies with long lead and realisation time (e.g. new power grids and large scale energy storage devices).

I. Introduction and Scientific Background

Nowadays many studies addressing power system analysis on a European scale are available. However, most of these studies deal with scenarios, pathways and technical options to achieve RE shares of nearly 80%. Only a small number of studies consider and discuss cover rates for renewable energies of more than 90% or almost 100% [1]. Furthermore, most of the conducted studies analyse only one (mostly economically optimised) distribution of the renewable generation capacities. However, the heterogeneous scenarios of existing studies show that the final system configuration is very sensitive to assumptions, such as investment costs or performance parameters of the addressed technologies. In addition, policies and consumer or market trends have decisively determined renewable energies expansion in recent years and will most likely have a major impact on the future power system design, too. However, these aspects are normally not considered in an explicit manner. As these effects and their impacts are very hard to assess, we use two different scenarios which indirectly reflect different possible outcomes. An understanding of the impact of different European expansion strategies on flexibility options such as storage, transmission grids and demand side management (DSM) has to be achieved. It is therefore necessary to look at a variety of RE compositions and to analyse how different strategic developments affect the requirements for such flexibility options. This can help to assess which common European RE development strategy turns out to be sustainable in the long term. As part of the research project REStoRE2050, an energy system model was developed to address such questions by performing simulations based on two given high RE scenarios; one focusing on wind energy and another one on solar energy. In this paper, the following central research questions are analysed: •

What are the main characteristics of the two existing high RE-electricity long-term scenarios for Europe in the year 2050, chosen as baseline for our own analyses?

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What are the impacts of these two scenarios on the usage characteristics and the ‘need’ of transmission grids, as well as on energy storage on a regional scale in Europe?

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Which interdependencies may arise between transmission grid and storage due to the different scenarios?