Initial investigation of liquid glass as a thermal medium in CSP plants

Abstract

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.

Utilizing high-temperature supercritical steam cycles instead of state-of-the-art subcritical ones promises higher CSP plant efficiencies and lower levelized cost of the generated electricity. A new glass composition, Haloglass RX, that can reach the required temperatures, is investigated for the use in central receiver CSP plants. It is compared to Solar Salt and liquid sodium in terms of its thermophysical properties. The fluid’s high viscosity and disadvantageous heat transfer capabilities make it appear unfeasible as the heat transfer fluid in an active direct storage cycle. However, due to a high volumetric heat capacity and low cost it is suitable as a storage medium with a differing heat transfer fluid. A cycle in which a liquid glass storage cycle separates the sodium receiver cycle and the ultra-supercritical steam generator is proposed. A thermal and economic model is developed and validated to compare the proposed plant layout to a state-of-the-art Solar Salt plant.