Concentrating Solar Thermal Energy

8Thermal Energy Storage

Aubin TOUZO¹, Quentin FALCOZ¹ and Gilles FLAMANT²

¹ PROMES-CNRS, UPVD, Perpignan, France

² PROMES-CNRS, Font-Romeu, France

8.1. Introduction

8.1.1. Advantages related to thermal energy storage

Although free and abundant, solar energy has a major drawback: it is intermittent. A solar power plant cannot generate during the night, or during cloudy spells, in the absence of a storage solution.

The integration of thermal energy storage in a concentrated solar power plant has three main advantages:

• – It compensates for the daily sunshine fluctuations, mainly due to cloudy spells. During cloudy spells, the power received by the transfer fluid varies, and this affects the power block supply. The scattered cloudy spells can be compensated by the thermal inertia of the transfer fluid or of various pieces of equipment (receivers, cladding, etc.), but as soon as the sunshine drops for several tens of minutes, the power block must be turned off. The power block generally involves a steam turbine or a gas turbine. This equipment is very sensitive, and the successive turn-ons and turn-offs generate significant maintenance expenses. Moreover, turbines are designed for a rated operating point. Storage makes operation at this rated point possible and thus maximizes the generated power output.
• – It shifts the production phase. The surplus energy generated during the day can be stored and then released later on. This leads to an increase in the capacity factor of the ...