Technical Details
Researchers at Aalto University created a thermal battery prototype using quartz sand as a heat storage medium. The system includes an insulated 0.2 m³ chamber heated electrically and a free-piston Stirling engine (1 kW output). Sand particles (0.6–2 mm grain size) offer thermal stability and material affordability.
Context and Background
While sand-based thermal storage is already used in Finland for heating applications, this is the first attempt to return energy to the grid as electricity. Unlike gravitational or chemical storage methods, the sand approach leverages low-cost, widely available materials, reducing scaling costs.
Industry Impact
The technology's potential lies in its adaptability for wind and solar-heavy energy systems. At 500 °C and optimized design, efficiency could reach 31.6%, making it competitive with existing solutions. However, current heat losses and thermal transfer challenges require further research.