Why do some solar thermal power systems utilize molten salt?

Molten salt is utilized in solar thermal power systems primarily for its ability to store thermal energy efficiently for later use. This capability is crucial for maintaining energy production even when sunlight is not available, such as at night or during cloudy periods. The molten salt can absorb and retain heat energy gathered from the sun during the day, which can then be released later to produce steam and drive turbines for electricity generation. This thermal energy storage allows for a more stable and reliable energy supply from solar power systems, enhancing their overall viability as a renewable energy source.

The other options do not adequately capture the primary role of molten salt in these systems. While molten salt does have some thermal absorption properties, the key factor for its use is not just heat absorption but rather its efficient energy storage capabilities. Furthermore, it does not evaporate quickly at high temperatures, which would be detrimental to its function in energy storage. Lastly, the increase in electrical efficiency is not directly attributable to the presence of molten salt but rather to the overall design and integration of the thermal storage system in solar power generation.