High-temperature heat storage for process heat

Many branches of industry, such as the chemical, steel and cement industries, require high-temperature process heat of 500 to over 1000 degrees Celsius. Until now, these temperatures have mostly been generated by fossil energy sources. However, the provision of heat on demand through the use of electricity from renewable energy sources in combination with heat storage systems offers opportunities for sustainable industrial heat generation. At the same time, the use and storage of waste heat can be integrated.

State of the art

Due to the high technical requirements in the high-temperature range, there are hardly any commercial storage solutions to date. One approach is to store heat in solid materials such as ceramics, steel or stone. Here, gas serves as a transport medium that absorbs the heat from a heat source or an electric heater and transports it to the solid by flowing through it. The solid material then stores the heat for a later point in time. The high amount of energy required to press the gas through the solid material prevents it from being used efficiently.

Technology

A liquid metal heat storage developed at the Karlsruhe Liquid Metal Laboratory (KALLA) at the Institute for Thermal Energy Technology and Safety (ITES) is a promising alternative for temperatures above 500 degrees Celsius. Thanks to its special material properties, liquid metal offers up to 100 times greater heat transfer than gas. The newly developed heat storage system is designed in such a way that the liquid metal circulates in a storage container filled with ceramic beads, where it releases and absorbs the heat. An initial test system was dimensioned for a heat capacity of 100 kilowatt hours.

Advantages

With the liquid metal heat storage, it is possible to store excess energy in the high-temperature range and make it available for further use as required. The technology is not only very efficient at transferring heat in the storage tank, but also at transporting heat from a heat source to a high-temperature process.

Options for companies

For further development and scaling, KIT is looking for companies that either want to cover their heat requirements with sustainable heat sources or whose processes generate large quantities of high-temperature waste heat. Cooperation in the area of components, e.g. heaters and measurement technology, is also of interest in order to develop components specifically for high temperatures.