Phase-Change Media for CSP Thermal Energy Storage

Concentrating solar troughs; from (nytimes.com 2010).

Thermal energy storage (TES) is a critical field of research for energy conversion applications. Nearly all conventional power generation plants require the generation of heat as a precursor to electricity generation (i.e., through thermodynamic power generation cycles). In concentrating solar power (CSP) plants, especially, TES is an integral design factor, owing to the variability of the sun's insolation and the inherent lack of solar radiation during dusk, night, and twilight hours. Without some means of thermal storage, CSP plants would find applicability only as adjuncts to conventional fossil fuel burning plants--e.g., supplementing the thermal energy generated by natural gas combustion with solar heat, allowing for improved turbine efficiencies (Mouawad 2010).

TES is crucial in the operation CSP plants, due to inopportune availability of insolation (in many localities, much of the electricity load occurs after sunset), variability in insolation due to weather events (e.g., clouds), improved control and distribution of power output (in the event of partial blackouts, for example), and potential scale-up of existing power plants by increase of their solar capacity factor (Herrmann and Kearney 2002).

FPL's combined natural gas / CSP plant; from (nytimes.com 2010).

Conventional storage systems make use of predominately sensible heat mechanisms--that is, they depend on the specific heat capacities alone of the materials incorporated therein. Typical examples include dual-tank systems (for liquid media) and thermoclines (for solid media) (Herrmann and Kearney 2002). Of greater interest to improve the cost of thermal energy storage are latent heat storage systems, which utilize phase change material(s) [PCM(s)]. PCMs allow for heat to be stored nearly isothermally due to the enthalpy change of phase transition--i.e., between solid and liquid, liquid and vapor, or solid and solid (different crystalline configurations). This characteristic can provide a greater energy storage density for circumstances in which the operating temperature range is comparatively narrow, or in which the PCMs of interest have relatively high enthalpy changes and moderate to high specific heat capacities (Goswami, Kreith et al. 2000).

This website will address the suitability and future potential of PCM for thermal energy storage TES, specifically in the operation of CSP. The general outline of this website is as follows.

Site Navigation

Please use the menus at the top or left to navigate this page.  The content of this site is organized as follows.

• Introduction
• Case Study: Micronal
• Sensible Heat Storage Systems
• PCM Overview
• Difficulties
• Future Work
• References

Contact

Any questions regarding this website can be directed to the author, Philip D. Myers, Jr.

Electronic mail

General Information: philipmyers@mail.usf.edu

Send mail to philipmyers@mail.usf.edu with questions or comments about this web site.