The Federal Ministry for Economic Affairs and Energy is funding a research project at TH Mittelhessen with four million euros. The aim is to develop energy-efficient facilities for a new urban district in Giessen . In addition to project manager Prof. Dr. Stefan Lechner from the Center for Energy Technology and Energy Management (etem.THM), other researchers from the Departments of Mechanical and Energy Engineering , Electrical and Information Engineering, and Civil Engineering are involved. THM is collaborating with the city of Giessen , the Giessen municipal utility company, Mittelhessen Netz GmbH, and Smart Power GmbH, a specialist in battery storage technologies from Feldkirchen near Munich. The partners will receive an additional 700,000 euros in funding. The project has a duration of four years.
The city of Giessen is planning a new district with over 300 apartments and commercial buildings on the eastern edge of the city center, on the former US motor pool site. Photovoltaic systems are to be installed on at least 50 percent of the residential rooftops. A total photovoltaic capacity of between 500 and 1500 kilowatts is planned.
Solar energy is also produced when it is not needed. And photovoltaic systems do not generate electricity at night. Therefore, for the energy transition to succeed, storage systems are needed to compensate for the highly fluctuating electricity supply and to stabilize the power grid.
The centerpiece of the energy management system in the planned district is a novel storage system that combines three different technologies. In a high-temperature storage unit, electric heating elements will generate heat of up to 1100 degrees Celsius from surplus electricity. This heat is stored in ceramic elements. When needed, it is converted into electricity and heating energy via a gas turbine. The resulting waste heat is used in the district heating network, in a large-capacity hot water storage tank, and by means of a heat pump. The third element of the system is a central battery storage unit for electricity.
The project partners expect that renewable energies will cover a significant portion of the neighborhood's electricity, heating, and electric vehicle charging needs during the summer months. The researchers also intend to investigate how the storage system can be used beyond the neighborhood boundaries. Lechner states that the project's main goal is "to make the energy and cross-sectoral flexibility potentials technically and economically usable both within and beyond the neighborhood boundaries, and to integrate them into a new system for neighborhood development.".
THMVice President and etem spokesperson Prof. Olaf Berger emphasizes the exemplary nature of the project: “The solutions developed will not only be important for the city of Giessen . They can serve as a template for the planning of energy-integrated urban districts of the future, in which energy demand in the electricity, heating and transport sectors is efficiently met.”
To operate neighborhood energy storage systems economically, changes to energy law are necessary, explains Dr. Fabio Longo, who advises THM . The specialist lawyer for administrative and energy law points out that the current structure of taxes and levies is not yet designed for the operation of energy storage systems.