Speed Of Reaching The Full Potential Heat Capacity Of A Basalt Product: Experimental Results

Renewable Energy Sources naturally deliver energy intermittently, causing fluctuations in energy supply. The energy is therefore also not provided corresponding to the actual need, but according to the availability. Hence, the demand for energy storage is rising with the increasing utilization of renewable energy sources, tackling the difficulties coming along with it. Carnot-Batteries are one out of a few geographically independent storage possibilities for longer durations. The thermal energy storages employed in Carnot-Batteries vary from liquid molten salt storage with two-tanks or single-tank thermocline storage to packed bed configurations with encapsulated PCM or natural solid materials, like rocks. Storage materials, which are found plenty in nature, having nearly no direct impact on the environment, are water and rocks. Natural Rocks offer a greater temperature span for operation than water and are therefore suitable for a wider range of applications. A possible natural rock for use in thermal energy storage is volcanic material basalt. In this experimental work, basalt, after its usage in cast form as flue pipes in a power plant, is analyzed, focusing on its properties for energy storage applications. Using this product would offer the reuse of an otherwise not anymore useful, leftover product and provide a storage material without the need of taking it from nature. The experimental research to retrieve the speed of reaching the full potential heat capacity of this product is described. The samples of basalt and the basalt product are analyzed at different temperatures from 300°C to 750°C. Additionally, air cooling, from these temperatures down to 100°C, and surface structure changes are evaluated. Insights into important boundary conditions for employment as storage material are given. In future work, it is anticipated to use these results as the base for a charging model of the basalt product and its validation.