High-temperature sensible thermal energy storage (STES) Thermo-economic assessment for various designs, storage materials and heat transfer fluids

An energy storage (ES) system is an economical and reliable technology that plays a
predominant role in making the renewable energy sector sustainable. Integration of ES with
wind and solar plants provides solution to problem of grid instability caused by to fluctuating
power output. The Thermal Energy Storage (TES) system is simple and has low environmental
and social impacts compared to other ES technologies like batteries, pumped hydro,
compressed air and chemical storage. However, application of a TES at high temperature is
quite unexplored and has a limited deployment globally.
Solid sensible TES (STES) stores excess electricity in form of sensible heat, the solid medium
is directly electrical heated or indirectly heated using heat transfer fluids (HTF). In STES
systems, no phase change nor chemical reactions involved. Hence, it is simple, easy to
maintain and the cost of construction materials is low. The foresaid advantages makes it
suitable for high temperature applications provided the solid material selected exhibits higher
temperature stability.
The poster will highlight the thermal performance of STES for 10 MWth power output over 24
hours, resulting in a storage capacity of 240 MWhth at high temperature of 800 °C. The
candidates of investigation are most commonly used solid materials, like high temperature
ceramic, high temperature concrete, firebricks, alferrock as well as vitrified flyash and as HTFs
Air, He, CO2 and N2 were studied. The influence of geometry, flow rate, heat transfer surface
area and solid material configuration in storage tank on the thermodynamics of TES system
cannot be ignored. Therefore, different STES designs were also included for assessment in
this research work.
To investigate the thermal performance of a STES system in terms of all the above-mentioned
candidates, a One-dimensional model will be developed in MATLAB and validated with data
available in literature. Based on results, the performance parameters like solid temperature
during charging/discharging cycle as well as overall thermal efficiency are evaluated. In addition, the economical assessment of different TES designs and materials can be estimated in €/MWhth.