Thermochemical Systems
In the Thermochemical Systems field of expertise, scientists are working on reversible gas-solid reactions and their application in the field of energy storage and conversion. Various reaction systems based on hydrogen or water vapour as a gaseous reaction partner are used for applications in building heat supply, industrial process technology and mobile applications. The main focus of the department is on the technological implementation of innovative storage and reactor concepts and their demonstration on a laboratory or pilot plant scale.
Fields of application
Lime storage for seasonal equalisation:
While considerable progress has been made in renewable electricity generation in recent years, the proportion of heating requirements covered by renewable technologies has so far been low. However, around 83 % of the final energy demand in an average German household is accounted for by heating and hot water and has so far been met mainly by burning fossil fuels. This means that the heating sector alone is responsible for 30 % of Germany's total energy-related CO2 emissions.
The reversible chemical storage of heat enables long-term storage without losses and is particularly suitable for applications in district heating supply when lime-based storage systems are used. Thanks to its high storage density and cost-effective materials, thermochemical storage offers a scalable solution for seasonal energy storage in single-family homes. By using lime-based storage systems, we are addressing a coupling of the electricity and heat sectors, but - in contrast to a heat pump - with a storage function for temporal decoupling.
Thermochemical high-performance reactors:
As part of the efficient and environmentally friendly mobility of tomorrow, we are investigating chemical hydrogen storage as well as heating/air conditioning from excess energy based on metal hydrides. Metal hydrides are formed when gaseous hydrogen combines with metals. This heat-tinted process, which can be repeated as often as required, stores hydrogen safely and can be used to generate heat or cold. In order to utilise these effects for storage or air conditioning, high-performance thermochemical reactors are required that enable rapid gas supply and very good heat transfer.
The pressure energy in the hydrogen tank is available anyway and has not been utilised to date. By being integrated into the hydrogen infrastructure of fuel cell vehicles, such air conditioning components can make an important contribution to efficient thermal management for electric vehicles (FC and battery).
Expertise
The principle of chemical heat storage offers various advantages, such as
- a high storage density
- loss-free long-term storage
- cost-effective storage materials
Depending on the reaction system, thermochemical storage can also be used in a wide temperature range - from below room temperature up to 1000 °C.
Long-term storage
Due to the chemical storage principle, the heat of reaction can be stored without loss. In combination with inexpensive storage materials, such as limestone, natural salts or reacting waste materials, cost-effective long-term storage systems can be developed.
Heat transformation
Due to the pressure dependency of the gas-solids reaction, thermochemical storage tanks can also be used to transform heat. The discharge temperature of the storage tank can be higher than the temperature required for charging. This is particularly interesting for the thermal valorisation of process heat.
Synergies with hydrogen as an energy source
The principle of chemical hydrogen storage has been studied for many years and is based on a chemical bond between the hydrogen gas and a solid. In the thermochemical systems field of expertise, the heat or cold generated during the reaction is utilised - this results in promising synergies with H2 as an energy carrier. For example, the pressure difference of the hydrogen flow (from the storage tank to the fuel cell) can be used to drive a refrigeration system or heat pump.
Current research and development
We are essentially working on the transfer of specific thermochemical material properties to a technically usable system. A central aspect of this is the qualification of reaction materials, which we are driving forward in close cooperation with our partners. At the same time, we develop innovative reactors in order to optimise the efficiency and performance of these materials. We demonstrate our systems and technologies in a laboratory environment in order to test their functionality under controlled conditions. Together with our partners, we then integrate these and develop operating strategies in a real environment