MAGNESIUM HYDRIDE FOR THERMAL-ENERGY STORAGE IN A SMALL-SCALE SOLAR THERMAL POWER-STATION

Magnesium hydride is a very promising thermal energy storage material. It will be used in a small-scale solar-thermal power station for terrestrial application. During insolation the hydride will be decomposed by part of the concentrated sunlight. The released hydrogen gas will be stored either in a pressure vessel or as a hydride in a low temperature alloy. With the other part of the solar energy electricity will be generated in a power conversion unit consisting of a Stirling engine and a generator. In times without insolation the Stirling engine can be driven with the heat of reaction released when hydrogen is recombined with magnesium. Simultaneously with the electricity generation process, heat can be provided by the power station. For the heat transfer between solar receiver, thermal energy store and Stirling engine, two potassium heat pipes will be used. The system will be operated between about 300-degrees-C and 480-degrees-C. The first two laboratory models will contain 20 kg of magnesium powder with a storage capacity of about 12 kW h. A detailed description of the laboratory model design and the expected operational characteristics is given.