Design and testing of a horizontal rock bed for high temperature thermal energy storage

Stefano Soprani, Fabrizio Marongiu, Ludvig Christensen, Ole Alm, Kenni Dinesen Petersen, Thomas Ulrich, Kurt Engelbrecht*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Integration of energy storage infrastructures into electrical grids represents a crucial milestone in the transition towards energy systems with high penetration of renewables. However, the high cost of the currently available technologies is a significant barrier for their implementation on the industrial scale. High temperature thermal energy storage systems, in combination with bottom steam cycles, are being investigated as potential cost-effective alternatives to traditional large-scale energy storage technologies. In this study, the performance of a rock bed high temperature energy storage unit is experimentally investigated. The rock bed has a storage capacity of 450 kWhth, was built to store heat at 600 °C and is characterized in terms of thermal efficiencies. Charge and discharge cycles were performed for different operating conditions and the temperature distribution across the bed was analyzed. A particular focus was set on the study of the impact of buoyancy forces on the temperature gradient inside the bed and on the storage unit efficiency. Different charging powers, flow concepts and rock bed configurations were discussed to optimize storage operations and led to an improvement in efficiency of the charging phase of 17%. A thermal round trip efficiency of around 68% was estimated for the best configurations and different improvement approaches were discussed for future research.
Original languageEnglish
Article number113345
JournalApplied Energy
Volume251
Number of pages14
ISSN0306-2619
DOIs
Publication statusPublished - 2019

Keywords

  • Energy storage
  • Rock bed
  • Regenerator

Cite this

Soprani, Stefano ; Marongiu, Fabrizio ; Christensen, Ludvig ; Alm, Ole ; Petersen, Kenni Dinesen ; Ulrich, Thomas ; Engelbrecht, Kurt. / Design and testing of a horizontal rock bed for high temperature thermal energy storage. In: Applied Energy. 2019 ; Vol. 251.
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title = "Design and testing of a horizontal rock bed for high temperature thermal energy storage",
abstract = "Integration of energy storage infrastructures into electrical grids represents a crucial milestone in the transition towards energy systems with high penetration of renewables. However, the high cost of the currently available technologies is a significant barrier for their implementation on the industrial scale. High temperature thermal energy storage systems, in combination with bottom steam cycles, are being investigated as potential cost-effective alternatives to traditional large-scale energy storage technologies. In this study, the performance of a rock bed high temperature energy storage unit is experimentally investigated. The rock bed has a storage capacity of 450 kWhth, was built to store heat at 600 °C and is characterized in terms of thermal efficiencies. Charge and discharge cycles were performed for different operating conditions and the temperature distribution across the bed was analyzed. A particular focus was set on the study of the impact of buoyancy forces on the temperature gradient inside the bed and on the storage unit efficiency. Different charging powers, flow concepts and rock bed configurations were discussed to optimize storage operations and led to an improvement in efficiency of the charging phase of 17{\%}. A thermal round trip efficiency of around 68{\%} was estimated for the best configurations and different improvement approaches were discussed for future research.",
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author = "Stefano Soprani and Fabrizio Marongiu and Ludvig Christensen and Ole Alm and Petersen, {Kenni Dinesen} and Thomas Ulrich and Kurt Engelbrecht",
year = "2019",
doi = "10.1016/j.apenergy.2019.113345",
language = "English",
volume = "251",
journal = "Applied Energy",
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Design and testing of a horizontal rock bed for high temperature thermal energy storage. / Soprani, Stefano; Marongiu, Fabrizio; Christensen, Ludvig ; Alm, Ole; Petersen, Kenni Dinesen; Ulrich, Thomas; Engelbrecht, Kurt.

In: Applied Energy, Vol. 251, 113345, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Design and testing of a horizontal rock bed for high temperature thermal energy storage

AU - Soprani, Stefano

AU - Marongiu, Fabrizio

AU - Christensen, Ludvig

AU - Alm, Ole

AU - Petersen, Kenni Dinesen

AU - Ulrich, Thomas

AU - Engelbrecht, Kurt

PY - 2019

Y1 - 2019

N2 - Integration of energy storage infrastructures into electrical grids represents a crucial milestone in the transition towards energy systems with high penetration of renewables. However, the high cost of the currently available technologies is a significant barrier for their implementation on the industrial scale. High temperature thermal energy storage systems, in combination with bottom steam cycles, are being investigated as potential cost-effective alternatives to traditional large-scale energy storage technologies. In this study, the performance of a rock bed high temperature energy storage unit is experimentally investigated. The rock bed has a storage capacity of 450 kWhth, was built to store heat at 600 °C and is characterized in terms of thermal efficiencies. Charge and discharge cycles were performed for different operating conditions and the temperature distribution across the bed was analyzed. A particular focus was set on the study of the impact of buoyancy forces on the temperature gradient inside the bed and on the storage unit efficiency. Different charging powers, flow concepts and rock bed configurations were discussed to optimize storage operations and led to an improvement in efficiency of the charging phase of 17%. A thermal round trip efficiency of around 68% was estimated for the best configurations and different improvement approaches were discussed for future research.

AB - Integration of energy storage infrastructures into electrical grids represents a crucial milestone in the transition towards energy systems with high penetration of renewables. However, the high cost of the currently available technologies is a significant barrier for their implementation on the industrial scale. High temperature thermal energy storage systems, in combination with bottom steam cycles, are being investigated as potential cost-effective alternatives to traditional large-scale energy storage technologies. In this study, the performance of a rock bed high temperature energy storage unit is experimentally investigated. The rock bed has a storage capacity of 450 kWhth, was built to store heat at 600 °C and is characterized in terms of thermal efficiencies. Charge and discharge cycles were performed for different operating conditions and the temperature distribution across the bed was analyzed. A particular focus was set on the study of the impact of buoyancy forces on the temperature gradient inside the bed and on the storage unit efficiency. Different charging powers, flow concepts and rock bed configurations were discussed to optimize storage operations and led to an improvement in efficiency of the charging phase of 17%. A thermal round trip efficiency of around 68% was estimated for the best configurations and different improvement approaches were discussed for future research.

KW - Energy storage

KW - Rock bed

KW - Regenerator

U2 - 10.1016/j.apenergy.2019.113345

DO - 10.1016/j.apenergy.2019.113345

M3 - Journal article

VL - 251

JO - Applied Energy

JF - Applied Energy

SN - 0306-2619

M1 - 113345

ER -