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Phase change material (PCM) candidates for latent heat thermal energy storage (LHTES) in concentrated solar power (CSP) based thermal applications - A review

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  • Jayathunga, D.S.
  • Karunathilake, H.P.
  • Narayana, M.
  • Witharana, S.

Abstract

Solar energy offers over 2,945,926 TWh/year of global Concentrating Solar Power (CSP) potential, that can be used to substitute fossil fuels in power generation and mitigate 2.1 GtCO2 of greenhouse gas (GHG) emission to support Sustainable Development Goals (SDGs) set by the United Nations (UN). Thermal energy storage (TES) is required in CSP plants to improve dispatchability, reliability, efficiency, and economy. Of all TES options, the latent heat thermal energy storage (LHTES) together with phase change materials (PCMs) exhibit the highest potential in terms of efficiency and economy. PCM properties thus become the ultimate decider of CSP performance. This paper reviews over 200 of published articles and websites to describe the history, identify the technologies, economics, and current trends of PCM as LHTES material for CSP plants. A list of 163 PCM candidates suitable for LHTES systems in low-temperature (T < 220 °C), medium-temperature (220 °C < T < 420 °C), and high-temperature (T > 420 °C) applications is presented for the first time. Research gaps are identified to determine the future directions.

Suggested Citation

  • Jayathunga, D.S. & Karunathilake, H.P. & Narayana, M. & Witharana, S., 2024. "Phase change material (PCM) candidates for latent heat thermal energy storage (LHTES) in concentrated solar power (CSP) based thermal applications - A review," Renewable and Sustainable Energy Reviews, Elsevier, vol. 189(PB).
    • Handle: RePEc:eee:rensus:v:189:y:2024:i:pb:s1364032123007621
    DOI: 10.1016/j.rser.2023.113904
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    1. Kalogirou, Soteris, 2003. "The potential of solar industrial process heat applications," Applied Energy, Elsevier, vol. 76(4), pages 337-361, December.
    2. Li, Qi & Li, Chuan & Du, Zheng & Jiang, Feng & Ding, Yulong, 2019. "A review of performance investigation and enhancement of shell and tube thermal energy storage device containing molten salt based phase change materials for medium and high temperature applications," Applied Energy, Elsevier, vol. 255(C).
    3. Cabeza, L.F. & Castell, A. & Barreneche, C. & de Gracia, A. & Fernández, A.I., 2011. "Materials used as PCM in thermal energy storage in buildings: A review," Renewable and Sustainable Energy Reviews, Elsevier, vol. 15(3), pages 1675-1695, April.
    4. N’Tsoukpoe, Kokouvi Edem & Schmidt, Thomas & Rammelberg, Holger Urs & Watts, Beatriz Amanda & Ruck, Wolfgang K.L., 2014. "A systematic multi-step screening of numerous salt hydrates for low temperature thermochemical energy storage," Applied Energy, Elsevier, vol. 124(C), pages 1-16.
    5. González-Roubaud, Edouard & Pérez-Osorio, David & Prieto, Cristina, 2017. "Review of commercial thermal energy storage in concentrated solar power plants: Steam vs. molten salts," Renewable and Sustainable Energy Reviews, Elsevier, vol. 80(C), pages 133-148.
    6. Xu, Ben & Li, Peiwen & Chan, Cholik, 2015. "Application of phase change materials for thermal energy storage in concentrated solar thermal power plants: A review to recent developments," Applied Energy, Elsevier, vol. 160(C), pages 286-307.
    7. Zhao, C.Y. & Zhang, G.H., 2011. "Review on microencapsulated phase change materials (MEPCMs): Fabrication, characterization and applications," Renewable and Sustainable Energy Reviews, Elsevier, vol. 15(8), pages 3813-3832.
    8. Milián, Yanio E. & Gutiérrez, Andrea & Grágeda, Mario & Ushak, Svetlana, 2017. "A review on encapsulation techniques for inorganic phase change materials and the influence on their thermophysical properties," Renewable and Sustainable Energy Reviews, Elsevier, vol. 73(C), pages 983-999.
    9. Nithyanandam, K. & Pitchumani, R., 2014. "Cost and performance analysis of concentrating solar power systems with integrated latent thermal energy storage," Energy, Elsevier, vol. 64(C), pages 793-810.
    10. Marta Muñoz & Antonio Rovira & María José Montes, 2022. "Thermodynamic cycles for solar thermal power plants: A review," Wiley Interdisciplinary Reviews: Energy and Environment, Wiley Blackwell, vol. 11(2), March.
    11. Mohammadi, Kasra & Khanmohammadi, Saber & Khorasanizadeh, Hossein & Powell, Kody, 2020. "A comprehensive review of solar only and hybrid solar driven multigeneration systems: Classifications, benefits, design and prospective," Applied Energy, Elsevier, vol. 268(C).
    12. Merchán, R.P. & Santos, M.J. & Medina, A. & Calvo Hernández, A., 2022. "High temperature central tower plants for concentrated solar power: 2021 overview," Renewable and Sustainable Energy Reviews, Elsevier, vol. 155(C).
    13. Ioan Sarbu & Calin Sebarchievici, 2018. "A Comprehensive Review of Thermal Energy Storage," Sustainability, MDPI, vol. 10(1), pages 1-32, January.
    14. Gunasekara, Saman Nimali & Pan, Ruijun & Chiu, Justin Ningwei & Martin, Viktoria, 2016. "Polyols as phase change materials for surplus thermal energy storage," Applied Energy, Elsevier, vol. 162(C), pages 1439-1452.
    15. Rezaei, Ehsan & Barbato, Maurizio & Ortona, Alberto & Haussener, Sophia, 2020. "Design and optimization of a high-temperature latent heat storage unit," Applied Energy, Elsevier, vol. 261(C).
    16. Modi, Anish & Bühler, Fabian & Andreasen, Jesper Graa & Haglind, Fredrik, 2017. "A review of solar energy based heat and power generation systems," Renewable and Sustainable Energy Reviews, Elsevier, vol. 67(C), pages 1047-1064.
    17. Nomura, Takahiro & Tabuchi, Kazuki & Zhu, Chunyu & Sheng, Nan & Wang, Shuangfeng & Akiyama, Tomohiro, 2015. "High thermal conductivity phase change composite with percolating carbon fiber network," Applied Energy, Elsevier, vol. 154(C), pages 678-685.
    18. Su, Weiguang & Darkwa, Jo & Kokogiannakis, Georgios, 2015. "Review of solid–liquid phase change materials and their encapsulation technologies," Renewable and Sustainable Energy Reviews, Elsevier, vol. 48(C), pages 373-391.
    19. Pizzolato, Alberto & Sharma, Ashesh & Maute, Kurt & Sciacovelli, Adriano & Verda, Vittorio, 2017. "Design of effective fins for fast PCM melting and solidification in shell-and-tube latent heat thermal energy storage through topology optimization," Applied Energy, Elsevier, vol. 208(C), pages 210-227.
    20. Ewelina Radomska & Lukasz Mika & Karol Sztekler, 2020. "The Impact of Additives on the Main Properties of Phase Change Materials," Energies, MDPI, vol. 13(12), pages 1-34, June.
    21. Rostami, Sara & Afrand, Masoud & Shahsavar, Amin & Sheikholeslami, M. & Kalbasi, Rasool & Aghakhani, Saeed & Shadloo, Mostafa Safdari & Oztop, Hakan F., 2020. "A review of melting and freezing processes of PCM/nano-PCM and their application in energy storage," Energy, Elsevier, vol. 211(C).
    22. Ferrer, Gerard & Solé, Aran & Barreneche, Camila & Martorell, Ingrid & Cabeza, Luisa F., 2015. "Corrosion of metal containers for use in PCM energy storage," Renewable Energy, Elsevier, vol. 76(C), pages 465-469.
    23. Oró, Eduard & Gil, Antoni & de Gracia, Alvaro & Boer, Dieter & Cabeza, Luisa F., 2012. "Comparative life cycle assessment of thermal energy storage systems for solar power plants," Renewable Energy, Elsevier, vol. 44(C), pages 166-173.
    24. Sharaf, M.A. & Nafey, A.S. & García-Rodríguez, Lourdes, 2011. "Thermo-economic analysis of solar thermal power cycles assisted MED-VC (multi effect distillation-vapor compression) desalination processes," Energy, Elsevier, vol. 36(5), pages 2753-2764.
    25. Hawlader, M. N. A. & Uddin, M. S. & Khin, Mya Mya, 2003. "Microencapsulated PCM thermal-energy storage system," Applied Energy, Elsevier, vol. 74(1-2), pages 195-202, January.
    26. Peiró, Gerard & Gasia, Jaume & Miró, Laia & Cabeza, Luisa F., 2015. "Experimental evaluation at pilot plant scale of multiple PCMs (cascaded) vs. single PCM configuration for thermal energy storage," Renewable Energy, Elsevier, vol. 83(C), pages 729-736.
    27. Tao, Y.B. & He, Ya-Ling, 2018. "A review of phase change material and performance enhancement method for latent heat storage system," Renewable and Sustainable Energy Reviews, Elsevier, vol. 93(C), pages 245-259.
    28. Ahmed Hassan & Mohammad Shakeel Laghari & Yasir Rashid, 2016. "Micro-Encapsulated Phase Change Materials: A Review of Encapsulation, Safety and Thermal Characteristics," Sustainability, MDPI, vol. 8(10), pages 1-32, October.
    29. Agyenim, Francis & Eames, Philip & Smyth, Mervyn, 2010. "Heat transfer enhancement in medium temperature thermal energy storage system using a multitube heat transfer array," Renewable Energy, Elsevier, vol. 35(1), pages 198-207.
    30. José Miguel Maldonado & Margalida Fullana-Puig & Marc Martín & Aran Solé & Ángel G. Fernández & Alvaro De Gracia & Luisa F. Cabeza, 2018. "Phase Change Material Selection for Thermal Energy Storage at High Temperature Range between 210 °C and 270 °C," Energies, MDPI, vol. 11(4), pages 1-13, April.
    31. Tehrani, S. Saeed Mostafavi & Taylor, Robert A. & Saberi, Pouya & Diarce, Gonzalo, 2016. "Design and feasibility of high temperature shell and tube latent heat thermal energy storage system for solar thermal power plants," Renewable Energy, Elsevier, vol. 96(PA), pages 120-136.
    32. Liu, Ming & Saman, Wasim & Bruno, Frank, 2012. "Review on storage materials and thermal performance enhancement techniques for high temperature phase change thermal storage systems," Renewable and Sustainable Energy Reviews, Elsevier, vol. 16(4), pages 2118-2132.
    33. Kenisarin, Murat M., 2010. "High-temperature phase change materials for thermal energy storage," Renewable and Sustainable Energy Reviews, Elsevier, vol. 14(3), pages 955-970, April.
    34. Manoj Kumar Pasupathi & Karthick Alagar & Michael Joseph Stalin P & Matheswaran M.M & Ghosh Aritra, 2020. "Characterization of Hybrid-nano/Paraffin Organic Phase Change Material for Thermal Energy Storage Applications in Solar Thermal Systems," Energies, MDPI, vol. 13(19), pages 1-15, September.
    35. Mao, Qianjun, 2016. "Recent developments in geometrical configurations of thermal energy storage for concentrating solar power plant," Renewable and Sustainable Energy Reviews, Elsevier, vol. 59(C), pages 320-327.
    36. Colella, Francesco & Sciacovelli, Adriano & Verda, Vittorio, 2012. "Numerical analysis of a medium scale latent energy storage unit for district heating systems," Energy, Elsevier, vol. 45(1), pages 397-406.
    37. Agyenim, Francis & Hewitt, Neil & Eames, Philip & Smyth, Mervyn, 2010. "A review of materials, heat transfer and phase change problem formulation for latent heat thermal energy storage systems (LHTESS)," Renewable and Sustainable Energy Reviews, Elsevier, vol. 14(2), pages 615-628, February.
    38. Islam, Md Tasbirul & Huda, Nazmul & Abdullah, A.B. & Saidur, R., 2018. "A comprehensive review of state-of-the-art concentrating solar power (CSP) technologies: Current status and research trends," Renewable and Sustainable Energy Reviews, Elsevier, vol. 91(C), pages 987-1018.
    39. Tian, Heqing & Du, Lichan & Wei, Xiaolan & Deng, Suyan & Wang, Weilong & Ding, Jing, 2017. "Enhanced thermal conductivity of ternary carbonate salt phase change material with Mg particles for solar thermal energy storage," Applied Energy, Elsevier, vol. 204(C), pages 525-530.
    40. Liu, Ming & Steven Tay, N.H. & Bell, Stuart & Belusko, Martin & Jacob, Rhys & Will, Geoffrey & Saman, Wasim & Bruno, Frank, 2016. "Review on concentrating solar power plants and new developments in high temperature thermal energy storage technologies," Renewable and Sustainable Energy Reviews, Elsevier, vol. 53(C), pages 1411-1432.
    41. Fornarelli, F. & Camporeale, S.M. & Fortunato, B. & Torresi, M. & Oresta, P. & Magliocchetti, L. & Miliozzi, A. & Santo, G., 2016. "CFD analysis of melting process in a shell-and-tube latent heat storage for concentrated solar power plants," Applied Energy, Elsevier, vol. 164(C), pages 711-722.
    42. Khan, Mohammed Mumtaz A. & Saidur, R. & Al-Sulaiman, Fahad A., 2017. "A review for phase change materials (PCMs) in solar absorption refrigeration systems," Renewable and Sustainable Energy Reviews, Elsevier, vol. 76(C), pages 105-137.
    43. Alva, Guruprasad & Lin, Yaxue & Fang, Guiyin, 2018. "An overview of thermal energy storage systems," Energy, Elsevier, vol. 144(C), pages 341-378.
    44. Zhang, H.L. & Baeyens, J. & Degrève, J. & Cacères, G., 2013. "Concentrated solar power plants: Review and design methodology," Renewable and Sustainable Energy Reviews, Elsevier, vol. 22(C), pages 466-481.
    45. Wong-Pinto, Liey-Si & Milian, Yanio & Ushak, Svetlana, 2020. "Progress on use of nanoparticles in salt hydrates as phase change materials," Renewable and Sustainable Energy Reviews, Elsevier, vol. 122(C).
    46. Shahsavar, Amin & Goodarzi, Abbas & Mohammed, Hayder I. & Shirneshan, Alireza & Talebizadehsardari, Pouyan, 2020. "Thermal performance evaluation of non-uniform fin array in a finned double-pipe latent heat storage system," Energy, Elsevier, vol. 193(C).
    47. Sharma, Atul & Tyagi, V.V. & Chen, C.R. & Buddhi, D., 2009. "Review on thermal energy storage with phase change materials and applications," Renewable and Sustainable Energy Reviews, Elsevier, vol. 13(2), pages 318-345, February.
    48. Wei, Gaosheng & Wang, Gang & Xu, Chao & Ju, Xing & Xing, Lijing & Du, Xiaoze & Yang, Yongping, 2018. "Selection principles and thermophysical properties of high temperature phase change materials for thermal energy storage: A review," Renewable and Sustainable Energy Reviews, Elsevier, vol. 81(P2), pages 1771-1786.
    49. Dowling, Alexander W. & Zheng, Tian & Zavala, Victor M., 2017. "Economic assessment of concentrated solar power technologies: A review," Renewable and Sustainable Energy Reviews, Elsevier, vol. 72(C), pages 1019-1032.
    50. Gil, Antoni & Medrano, Marc & Martorell, Ingrid & Lázaro, Ana & Dolado, Pablo & Zalba, Belén & Cabeza, Luisa F., 2010. "State of the art on high temperature thermal energy storage for power generation. Part 1--Concepts, materials and modellization," Renewable and Sustainable Energy Reviews, Elsevier, vol. 14(1), pages 31-55, January.
    51. Adrián Caraballo & Santos Galán-Casado & Ángel Caballero & Sara Serena, 2021. "Molten Salts for Sensible Thermal Energy Storage: A Review and an Energy Performance Analysis," Energies, MDPI, vol. 14(4), pages 1-15, February.
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    CSP; TES; LHTES; PCM; SDG;
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