Group "High-temperature heat storage and process technology"
Energy storage plays a key role in the energy transition, as many renewable sources such as solar and wind are subject to natural fluctuations caused by daily and annual cycles, as well as weather conditions. Energy storage systems are the key to compensating for this fluctuating supply and ensuring that energy is available when needed. With the help of liquid metals, it is possible to store heat even at very high temperatures, beyond 600°C, which are typical for industrial, often energy-intensive high-temperature processes (more information in our data sheet). The KIT junior research group ‘Liquid metal-based heat storage – the key to CO2-free high-temperature processes’ aims to demonstrate the technical feasibility of fixed-bed storage systems using liquid metals as heat transfer media. To this end, we are demonstrating novel heat storage systems from laboratory to pilot scale, testing compatible and cost-effective storage materials in liquid metal, and put components (pumps, valves) to test in a liquid metal loop. The work is complemented by comprehensive numerical simulation of the complex mass and heat transport processes in the heat storage systems.
In addition, we are investigating the possible applications of liquid metals in process engineering, as their outstanding heat transfer properties and other characteristics, such as their comparatively high density, which promotes certain separation effects, make them particularly suitable as heat transfer and process fluids. We are currently investigating the CO2-free production of hydrogen and carbon through the thermochemical cracking of methane in liquid tin in a bubble column reactor. The combination of methane pyrolysis with further process steps for the production of valuable carbon from atmospheric CO₂ is an example of a process chain in which so-called negative emission technologies (NET) serve as the basis for value-added products. To this end, we are investigating the reaction mechanisms of methane pyrolysis on a laboratory and pilot scale and developing suitable reactor concepts.
Further research results can be found in current publications.
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THERMIA
The THERMIA project is conducting experimental research into high-temperature heat storage. The DUO-LIM (DUal-Media thermocline energy stOrage with LIquid Metal) heat storage system is based on the principle of a packed bed storage system. In this system, heat is stored primarily within solid zirconium silicate particles. These particles are thermally charged and discharged using liquid metal (lead-bismuth eutectic: LBE) as a heat transfer medium. So-called thermocouple lances can be used to measure the temperature profile in the storage system, and investigate the processes taking place in the storage system, for example by varying the inlet mass flows and temperatures.
Funding: KSB Foundation project: THERMIA (Nr. 1.1407.2024.1) Contact: Florian Kreißig |
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Storage material
Using low-cost storage materials can reduce the overall cost of the storage system. KALLA is collaborating with the Institute for Pulsed Power and Microwave Technology (IHM) to research more cost-effective storage materials for use in our liquid metal fixed-bed heat storage systems. The research focuses on investigating natural materials, such as natural stones and slag from the steel industry. Since liquid metal is highly corrosive at high temperatures, the corrosion resistance of each potential storage material is assessed by exposing it to lead at 750 °C over a longer period of time.
Funding: Helmholtz MTET Topic 4.3 Contact: Margaux Zehnder |
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LIMELISA
In the LIMELISA project, we are testing central components such as pumps and fittings in a high-temperature circuit on a pilot scale. To this end, the compatibility of various materials at 700 °C was first investigated in order to then design and build both the components and the circuit as part of the project. The components are then tested in dynamic operation at 700 °C in liquid lead.
Funding: BMWE, FKZ 03EE5050C Project partners: KSB SE & Co. KGaA, DLR Contact: Martin Lux |
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PACKMEN
While charging and discharging packed‑bed heat storage systems, a temperature front (thermocline) forms and moves through the storage tank. The thickness and behaviour of the thermocline are crucial for the efficiency of the storage. A detailed understanding of the underlying heat transport mechanisms is therefore essential for the further optimisation and design of the storage systems. Because liquid metals have a very high thermal conductivity, the heat transport mechanisms differ fundamentally from those of conventional fluids. In particular, the effective thermal conductivity in the packed bed with liquid metals as heat transfer fluid has not been sufficiently studied for the operating range of the storage. To investigate these phenomena in the packed bed experimentally, a new test section is being built for performing thermal step‑response measurements.
Funding: DFG Priority Programme: “Carnot Batteries: Inverse Design from Markets to Molecules“ (SPP 2403); Project 526152734 Contact: Eike Schmidt |
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BioNECH2
The BioNECH2 project is conducting experiments to investigate the applicability of pyrolysis respectively dry reforming of biogas in a liquid metal-based bubble column reactor. Two different small-scale pilot plants are available for this purpose. Liquid tin is used to achieve continuous operation of the reactor at temperatures of up to 1200 °C. The feed gas is thermally decomposed in the liquid metal as the bubble rises, and the resulting solid carbon is formed as a powder. Due to the large difference in density compared to the liquid metal, this floats to the top and can be easily separated. In addition to investigations into the compositions of the reactant gases, the research focuses on scale-up, reactor development and the investigation of the resulting carbon. Further information
Funding: Vector Stiftung Contact: Marie Gutsch |
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Contact:
Dr.-Ing. Klarissa Niedermeier
Phone +49 721/608-26902
klarissa.niedermeier∂kit.edu
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