Sistemi di accumulo dell’energia termica - Luisa F. Cabeza (GREiA Research Group, University of Lleida)

© 2019 GREiA, University of Lleida
Materials for thermal energy storage
Le tecnologie per l'accumulo termico nelle Smart grid
Cagliari, Italy
Dr. Luisa F. Cabeza

2Dr. Luisa F. Cabeza – October 2019
Contents
• Introduction
• Materials for TES

Basic principle of TES
• A complete storage process involves at least three
steps:
• Charging
• Storing
• Discharging
Mehling H, Cabeza LF. Heat and cold storage with PCM. An up to date
introduction into basics and applications. Springer, 2008.

Basic principle of TES
• The technical and economical requirements for an
energy storage system are determined by its actual
application within the energy system
• Therefore any evaluation and comparison of energy
storage technologies is only possible with respect to
this application
• The application determines the technical
requirements (e.g. type of energy, storage capacity,
charging/discharging power, etc.) as well as the
economical environment (e.g. expected pay-back
time, price for delivered energy, etc.)

Benefits of TES
• The systems achieve benefits by fulfilling one or
more of the following purposes:
• Increase generation capacity
• Enable better operation of cogeneration plants
• Shift energy purchases to low cost periods
• Increase system reliability
• Integration with other functions
Figure from Andreas Hauer

Thermal Energy Storage
L.F. Cabeza, A. Gutierrez, C. Barreneche, S. Ushak, A.G. Fernández, A.I Fernández, M. Grágeda
Renewable and Sustainable Energy Reviews 42 (2015) 1106-1112

• Maturity of TES technologies
A. Gutierrez, L. Miró, A. Gil, J. Rodríquez-
Aseguinolaza, C. Barreneche, N. Calvet, X. Py, A.I.
Fernández, M. Grágeda, S. Ushak, L.F. Cabeza
Renewable and Sustainable Energy Reviews 59
(2016) 763-783

Sensible Latent
Sorption & chemical
reactions
Thermochemical
(kJ/kg)
Temperature(ºC)
Stored heat (kJ/kg)
Temperature(ºC)
Stored heat
A(s)
heat storage
endothermic reaction
heat release
exothermic reaction
B(s) + 𝐶(g)
STORAGE
CHARGE
DISCHARGE

TES technologies
• Heat storage as sensible heat
– solids (stone, brick,…)
– liquids (water,…)
The most common method for heat storage.
Stored heat
Temperature
sensible
TcmQ 

Stored heat
Temperature
sensible
sensible
latent
sensible
Temperature of
phase change
Materials with useful phase change
= latent heat storage material,
= phase change material (PCM)
TES technologies
• Heat storage as latent heat
– evaporation at constant
volume  temperature and
pressure change
– evaporation at constant
pressure  volume change
or open system
– melting at constant pressure
 small volume change
 no temperature change
hmQ 

TES technologies
• Sorption and thermochemical storage
• Uses reversible chemical reactions to store thermal
energy in the form of chemical compounds
• This energy can be discharged at different temperatures,
dependent on the properties of the thermochemical
reaction

TES application potential
• Matching supply and demand

• Matching supply and demand: seasonal storage
A. Dahash, F. Ochs, M.B. Janetti, W. Streicher.
Applied Enregy 239 (2019) 296-315

• Power vs. Energy

• Building applications
– Passive systems in the envelope
– Active systems in the envelope (ventilated façade)
– DHW solar energy with PCM in water tank
• High temperature applications
– Solar cooling
– Industrial waste heat recovery
– Storage in CSP
• Other applications
– General containers
– Beverages
– Catering
– Blood products
– Electronic devices

Contents
• Introduction
• Materials for TES

Classes of materials
• Any material can be used for thermal energy
storage (TES)
• The selection of the material depends on:
– The application
– The requirements of the application:
• Temperature
• Power
• Energy density
– The properties of the material:
• Energy density
• Stability (chemical, physical, etc.)
• TES technology used
• …

Classes of materials
• Classes of materials
A. Fallahi, G. Guldentops, M. Tao, S. Granados-Focil,
S. Van Dessel. Applied Thermal Engineering 127
(2017) 1427-1441

Sensible TES
– Water (tanks, pits)
– Rocks/bricks/ceramics
– Metals
– Molten salts
Usually classified by the
application

Sensible TES
– Water (tanks, pits)
• Widely available
• Cheap
• High energy density
A. Dahash, F. Ochs, M.B. Janetti, W. Streicher.
Applied Energy 239 (2019) 296-315
Y. Pal Chandra, T. Matuska. Energy and Buildigns 187
(2019) 110-131

Sensible TES
– Ceramics
• Highly used
• Low cost
• Low thermal cycling (they break under thermal stress)

Sensible TES
A. Gil, M. Medrano, I. Martorell, A. Lázaro, P. Dolado, B. Zalba, L.F. Cabeza.

Sensible TES
– Metals and metal alloys
• High thermal diffusivity
• Low thermal energy density
• Considerations:
– There is a lack of consciousness about the implications of the
metallurgic aspects related to melting and solidification of metals
and metal alloys under thermal cycling at high temperatures
A.I. Fernández, C. Barreneche, M. Belusko, M. Segarra, F. Bruno, L.F. Cabeza
Solar Energy Materials and Solar Cells 171 (2017) 275-281

Sensible TES
– Metals and metal alloys
A.I. Fernández, C. Barreneche, M. Belusko, M. Segarra, F. Bruno, L.F. Cabeza
Solar Energy Materials and Solar Cells 171 (2017) 275-281

Sensible TES
– Metal alloys
G. Wei, G. Wang, C. Xu, X. Ju, L. Xing, X. Du, Y. Yang

Sensible TES
– High temperature concrete and castable ceramic

Sensible TES
– Molten salts: solar salt
• Highly corrosive
• Low thermal conductivity

Sensible TES
– Molten salts

Sensible TES
– Other materials used for high temperature

Sensible TES
– Wastes and by-products: bischofite
A. Gutierrez, L. Miró, A. Gil, J. Rodríquez-Aseguinolaza, C. Barreneche,
N. Calvet, X. Py, A.I. Fernández, M. Grágeda, S. Ushak, L.F. Cabeza

Sensible TES
– Wastes and by-products: slags

Sensible TES
• Requirements of the materials
Thermal requirements
- High energy density
- Good specific heat capacity
- High thermal conductivity
- Low thermal diffusivity
- Service temperature range fitted to the
application
- Low thermal expansion coefficient
Physical and technical requirements
- High density
- High cycle stability
- Non-corrosiveness
- Low system complexity
- Low vapour pressure in the service temperature range

Sensible TES
Economic requirements
- Low price
- Large scale production methods
Recyclability and safety requirements
- Non-toxicity
- Recyclable or reusable
- Low CO2 footprint
- Low embodied energy
For a good selection of the proper material, we
need to rank the requirements and to evaluate a
compromise between contradictory or competing
requirements

Latent TES
– Inorganic substances
• Water/ice
• Salt hydrates
• Salts
– Organic substances
• Paraffin
• Fatty acids
• Polymers (HDPE)
• BioPCM (esters, etc.)
Usually classified by the
nature of the material

Latent TES
Organics Inorganics
Advantages
- No corrosives
- Low or none subcooling
- Chemical and thermal stability
Advantages
- Greater phase change enthalpy
- Higher energy density
Disadvantages
- Lower phase change enthalpy
- Low thermal conductivity
- Flammability
- Bad compatibility with plastics
Disadvantages
- Subcooling
- Corrosion
- Phase separation
- Phase segregation, lack of
thermal stability
L.F. Cabeza, A. Castell, C. Barreneche, A. de Gracia, A.I Fernández

Latent TES
Inorganic
Organic
(2017) 1427-1441

Latent TES
Solid-solid organic PCM
(2017) 1427-1441

Latent TES
– Water/ice
• It is the oldest PCM, used since prehistory
• Its use for cold drinks is a clear example of TES material

Latent TES
– Salt hydrates
Y. Lin, G. Alva, G. Fang. Energy 165 Part A
(2018) 685-708

Latent TES
– Salts
(2018) 685-708

Latent TES
– Eutectic salts
(2018) 685-708

Latent TES
– Polymeric solid-solid PCM
(2017) 1427-1441

Latent TES
– Organic solid-solid PCM
(2017) 1427-1441

Latent TES
– Organometallic solid-solid PCM
(2017) 1427-1441

Latent TES
– Inorganic solid-solid PCM
(2017) 1427-1441

Latent TES
– Metal and metal alloys
(2018) 685-708

Latent TES
– Wastes and by-products: bischofite

Latent TES
– Wastes and by-products: astrakanite and kainite

Latent TES
- Suitable phase change temperature fitted to the application
- Large phase change enthalpy and specific heat
- Reproducible phase change
- Good thermal stability
- Low density variation and small volume change
- High chemical and physical stability
- Small or no subcooling
- Non-corrosiveness (good compatibility with other materials)
- Low vapour pressure in the service temperature range

Latent TES
- Low price
- Non-toxicity
- Low CO2 footprint

Sorption & chemical reactions
J. Cot-Gores, A. Castell, L.F. Cabeza
C. Prieto, P. Cooper, A.I. Fernández, L.F. Cabeza

– Chemical reactions: gas/solid reactions
• Hydration reaction:
• Carbonation reaction:
• Ammonia decomposition:
• Metal oxidation reactions:
• Sulphur cycle:

Renewable and Sustainable Energy
Reviews 16 (2012) 5207-5224

L.F. Cabeza, A. Sole, C. Barreneche
Renewable Energy 110 (2017) 3-39

– Adsorption
• Gas-solid processes (physisorption or chemisorption)
• Open/closed
– Absorption
• Gas-liquid processes
• Open/closed
A. Sole, I. Martorell, L.F. Cabeza

- Reversible reaction
- Control of the kinetic model
- Control of the crystallographic structure changes
- Water stability with the crystal structure
- Proper particle size
- Control of the impurities
- Solubility of the material in the working conditions
- Suitable working temperature range fitted to the applications
- Thermal stability

- High chemical and physical stability
- Non-corrosiveness (good compatibility with other materials)
- Low price
- Non-toxicity
- Low CO2 footprint

- Low price
- Non-toxicity
- Low CO2 footprint

Acknowledgements
© 2019 GREiA, University of Lleida
This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de
España (RTI2018-093849-B-C31).
Funding has also been received from European Union’s Horizon 2020 research and innovation
programs under projects Innova MicroSOLAR (723596), HYBUILD (768824), SWS-HEATING
(764025) and SolBio-Rev (814945).
The authors at the University of Lleida would like to thank the Catalan Government for the
quality accreditation given to their research group (2017 SGR 1537). GREiA is certified agent
TECNIO in the category of technology developers from the Government of Catalonia. This work
is partially supported by ICREA under the ICREA Academia programme.

Thank you for your attention!
www.greia.udl.cat
lcabeza@diei.udl.cat

Sistemi di accumulo dell’energia termica - Luisa F. Cabeza (GREiA Research Group, University of Lleida)

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