Name a common thermal energy storage system.

An ice storage system is a well-known thermal energy storage system that works by using ice as a medium for storing energy. In this system, ice is created during off-peak electricity hours, typically at night when energy demand is lower and electricity costs are cheaper. During the day, when electricity demand is high, the stored ice is used for cooling purposes, such as in air conditioning systems. This approach can reduce energy costs and optimize energy usage, making it a practical solution for managing thermal loads in buildings and industrial processes.

The other options mentioned do not qualify as thermal energy storage systems. A solar panel system primarily generates electricity from sunlight but does not inherently store thermal energy. A wind turbine system generates electricity from wind energy and also does not focus on thermal energy storage. Similarly, a geothermal heating system utilizes the Earth's heat for direct heating or electricity generation but does not operate as an energy storage system in the same way that an ice storage system does. Thus, the ice storage system is specifically designed for the purpose of thermal energy storage, making it the correct answer.