Daniel Scharrer

Reducing primary energy use and greenhouse gases are central goals of the energy transition. However, switching from fossil to regenerative energy sources is not enough to achieve them. An overarching view and optimization of the different sectors of the energy system - electricity, gas, heat and transport - can significantly advance the further development of the energy system in Germany. Potential exists above all on a regional level.

The goal of the ESM-Regio project - short for "Multisectoral Coupled Energy System Modeling on a regional level" - is to create a temporally high-resolution energy system model on a county level that takes into account the four sectors of electricity, gas, heat and transport as well as the required interface technologies. A key feature of the project is a cross-sector model logic. Suitable simulation methods enable a holistic analysis and optimization of the system operation under consideration of the four relevant sectors of the energy system.

The share of electricity from photovoltaics in the electricity mix in Germany has been greatly expanded in recent years. In the near future, electricity generation from renewable energies and thus also solar generated electricity will continue to increase. At high solar radiation, this already leads to a local oversupply in the power grid, while the photovoltaic at night naturally can not contribute to the power supply. Ensuring the nightly base load at night is therefore largely ensured by fossil production from coal and lignite with corresponding CO2 emissions.

By using base load storage systems with low-temperature storage, the use of polluting thermal power plants should be reduced. During the day, heat from geothermal energy or industrial processes is upgraded with excess electricity from photovoltaics using heat pumps (HP) and stored in a low-temperature storage system. To generate nocturnal base load power, this heat energy is then removed from the storage via an Organic Rankine Cycle (ORC) process.

The aim of the project is the dynamic simulation of energy flows in HP-ORC heat storages that are integrated into the energy system and use excess heat and power. With the simulation models, the dimensioning and suitable operating modes for the economic operation of low-temperature storage systems should be investigated.