4.4 Power extraction
The following means of conversion of stored thermal energy to steam are
available:
● flashing high-temperature water to steam and lower-temperature water by
throttling the pressure, then passing steam through a peaking or a main turbine;
● using the hot water as boiler inlet feedwater, thus reducing the energy diverted
for feedwater heating from the main turbine, increasing its output – a so-called
feedwater storage system; and
● using heat exchangers to transfer the energy to cold feedwater, producing
either superheated steam or hot feedwater – low vapour-pressure storage
media.
There are three main ways of operating the containment vessel or, as it is
usually called, accumulator; namely variable pressure, expansion or displacement