Storing solar energy with new materials
The interdisciplinary NEOTHERM junior research group at Otto von
Guericke University in Magdeburg is developing new materials for storing
thermal energy. Using new composite materials, the scientists at the
Faculty of Process and Systems Engineering (FVST) want to recover and
store unused solar thermal energy and waste heat from industry. This
energy can be used, for example, for heating domestic hot water or for
The chemists and material experts at Otto von Guericke University, Magdeburg (OVGU), want to develop new composite materials with large surfaces and a high energy storage density, which can absorb considerable water. For this purpose, the NEOTHERM junior research group wants to develop new materials as substrates, coat them with highly porous powders and optimise the sorptive properties of the composites.
The water sorption, provides the capability to store heat. “Molecules that accumulate on a surface lose their mobility and release energy. The surface can be activated again by adding energy. This process is comparable with water evaporating on my arm. When it dries, the water molecules vanish and the energy used for this is drawn from the skin. The evaporation process makes the arm feel cold,” says Dr Alexandra Lieb, explaining the underlying principle. “Hot air will be drawn through the water-soaked materials that we are developing, creating moist, cold air. The heat remains in the material and is stored.” As soon as the heat, in other words the energy, is required again, the water is simply added again as vapour, adds Lieb. The substrate materials are being developed in close cooperation with the Institute for Materials and Joining Technology (IWF).
Composite materials for thermo-chemical storage
The interdisciplinary junior research group entitled “Innovative Composite Materials for Thermal-chemical Energy Storage” (NEOTHERM) intends to develop, characterise and assess micro-macro-porous composite materials for thermochemical energy storage. The aim is to provide sorption materials for water as a sorbate with high storage densities, effective thermal transfer and application-adapted sorption temperatures (»20 to 500 °C) along with a suitable temperature range for both storing solar thermal heat as well as recycling energy from technical processes. For this purpose it is intended to develop cellular materials as substrate materials and to optimise them in terms of their chemical, morphological and thermal properties. As active components for thermal storage, it is also intended parallel to this to develop and/or modify micro-porous crystalline compounds (metal organic frameworks = MOFs and zeolites) that shall be fixed to the substrate, for example using in-situ crystallisation or a substrate link reaction.
The following aspects of the material compounds will be dealt with:
- Synthesis of new or modified micro-porous materials (active components)
- Development of manufacturing processes for macro-porous monolithic materials with variable surface-based chemical and thermal properties and specifically set, open porosity (substrates)
- Coating/surface modification of open-cell foams for setting the sorption properties of the compound materials
- Control of ad- and desorption processes in porous solids by controlling the pore size and shape
- Evaluation of the long-term behaviour of the thermal storage materials. Right from the beginning, the innovative materials are being developed with a view to their technical deployment in terms of the work temperature, the charging/discharging behaviour, the long-term stability, the storage density as well as the costs and safety.
The basic researchers at Magdeburg University are working together with an industrial partner, SorTech, which is a medium-sized enterprise from Saxony-Anhalt. The German Federal Ministry for Education and Research is spending around 2.5 million euros on funding the NEOTHERM project for the next five years.