The sun as energy source suffers from a temporal mismatch between energy production and consumption. The development of efficient heat storage concepts allows for a temporal shift, utilizing excess heat collected in times of high availability / low demand during times of low availability / high demand. In solar thermal systems exists huge potential for storage of excess heat harvested during high-production phases for consumption during low radiation periods. Thermochemical energy storage (TCES, fig.1) - featuring high storage densities, variable temperature levels and the potential of miniaturizing storage systems - is a highly promising concept for this challenge. So far, neither suitable TCES-materials, nor a prototype-setup compatible with temperatures below 400 °C, provided by many solar thermal collector systems, was at hand. With the development of the [Cu(NH3)4]SO4 / CuSO4 TCES-system a perfectly cycle stable, fast-reacting system featuring a storage density of 1.77 GJ m-3 and allowing for a temperature increase within 20 seconds from 25 °C to over 300 °C, was identified. We present our way from the material development in the lab, a detailed understanding of the materials properties and potential, to a first (100 g scale, see fig.2) and a second prototype-phase (3 kg scale), leading to the conception of a prototype on a 1 m3 scale for combination with a solar thermal collector system.

Thermochemical energy storage materials for combination with solar thermal collector systems

2019 Spring National Meeting

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