The operation of power plants must meet a series
of requirements in order to enable the increasing
penetration of intermittent renewable energy and the
consequent intensifying demand for flexible generation.
It is proposed here that during off-peak demand, steam
can be extracted from Rankine-cycle power stations for
the charging of thermal storage tanks that contain
suitable phase-change materials (PCMs); during peak
demand time, these thermal energy storage (TES) tanks
can act as the heat sources of secondary thermal power
plants in order to generate power, for example as
evaporators of organic Rankine cycle (ORC) plants that
are suitable for power generation at reduced
temperatures and smaller scales. This type of solution
offers greater flexibility than TES-only solutions that
store thermal energy and then release this back to the
base power station, in that it allows both derating and
over-generation compared to the base power-station.
The approach is here applied to a case study of a 670-
MW rated nuclear power station, since nuclear power
stations are generally suitable for baseload generation
and the proposed system configuration could increase
the operational flexibility of such plants.