Molten Salt Power Plants

General Characteristics

A concentrated solar power plant converts solar energy to electricity. It is based on focusing solar energy from a large area onto a small receiver using concentrators such as mirrors or lenses. Light is converted to heat which, in turn, drives steam and power generators to provide electricity.

Various technologies are in use regarding each of the steps of light-electricity conversion. A solar field is composed of reflectors concentrating light onto a receiver. They are usually equipped with trackers which follow the sun position to maximise the amount of harvested energy. The receiver can be integrated with the reflectors (which is the case with parabolic trough, enclosed trough, and Fresnel plants), or it can stand alone (e.g., in solar towers). The latter approach seems to be the most promising . The receiver distributes the gathered heat with the use of a heat transfer fluid (HTF). Energy storage is introduced in order to smooth power output. It also lets us release energy in a timed and controlled manner, especially if none is being generated. Therefore, it enables prolonged, after-sunset operations. Next, the HTF is delivered to the steam generator. Finally, the steam reaches an electric generator which produces electricity.

In a concentrated solar power plant, molten salt is used as the HTF, hence the name. Molten salt is more economically viable than other HTFs, such as mineral oil.

An important advantage of Molten Salt Power Plants, compared to other renewable technologies such as solar photovoltaic (PV) plants, is its flexibility. Molten Salt Power Plants feature short-term heat storage, which allows them to provide more constant output even during periods of cloudy weather or after sunset.

Given the extra flexibility provided by using molten salt energy storage and intelligent control, such plants can be used as supplementing installations for other types of renewable generators, for instance, wind turbine farms.

Molten Salt Power Plants make it possible to charge thermal molten-salt storage tanks with solar energy at rational cost during the daytime and generate power when needed after dusk. Thanks to this “as-needed” power supply, which is independent of the available sunlight, these systems are a key element in the energy turnaround. Molten Salt Power Plants seem to be the most promising regarding both economic and technical solutions.