Abstract
Pumped-thermal energy storage (PTES) systems consume and produce electrical energy using thermal storage media as an intermediate stage. PTES lends itself to long-duration energy storage to facilitate high penetration of intermittent electricity generation. This study presents a model-based comparison of two thermal storage types within a PTES system: a conventional, single-phase, stratified water-glycol sensible storage system (SGS), and an ideal isothermal, two-phase heat exchanger that freezes a water reservoir (isothermal heat exchanger (IHEX)). The SGS thermal storage capacity is based on the liquid's sensible heat change with temperature, whereas the capacity of the IHEX is based on the latent heat of isothermally freezing and melting water. The idealized IHEX modeled here undergoes steady-state melting and freezing (in contrast to transient rates, as observed with ice-on-coil storage). A computational model of a complete PTES system is presented and used to evaluate the PTES system-level performance with each type of cold storage. Compared to SGS-based PTES, under nominal operating conditions, the IHEX-based PTES increased electrical round-trip efficiency from 61% to 82% and increased energy density from 1.13 to 8.09 kWh/m3 The performance of the PTES configured with IHEX storage was also analyzed under varying operating parameters.
| Original language | English |
|---|---|
| Article number | 070905 |
| Journal | Journal of Energy Resources Technology, Transactions of the ASME |
| Volume | 143 |
| Issue number | 7 |
| DOIs | |
| State | Published - Jul 2021 |
Funding
This work was sponsored by the U.S. Department of Energy’s Building Technologies Office under Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC. The authors would like to acknowledge Mr. Antonio Bouza, Technology Manager— HVAC&R, Water Heating, and Appliance, U.S. Department of Energy Building Technologies Office. The Department of Energy will provide Public Access to these results of Federally Sponsored Research in Accordance with the DOE Public Access Plan.2 We would like to thank Oak Ridge National Laboratory’s Innovation Crossroads Program, sponsored by the U.S. Department of Energy’s Advanced Manufacturing Office and Tennessee Valley Authority, for their support. The authors would also like to acknowledge Olivier Dumont from University of Liège for contributions during the development process of the model, and Viral Patel for review of the paper. This work was sponsored by the U.S. Department of Energy's Building Technologies Office under Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC. The authors would like to acknowledge Mr. Antonio Bouza, Technology Manager-HVAC&R, Water Heating, and Appliance, U.S. Department of Energy Building Technologies Office. The Department of Energy will provide Public Access to these results of Federally Sponsored Research in Accordance with the DOE Public Access Plan.2 We would like to thank Oak Ridge National Laboratory's Innovation Crossroads Program, sponsored by the U.S. Department of Energy's Advanced Manufacturing Office and Tennessee Valley Authority, for their support. The authors would also like to acknowledge Olivier Dumont from University of Li?ge for contributions during the development process of the model, and Viral Patel for review of the paper.
Keywords
- Energy conversion/systems
- Energy storage systems
- Isothermal
- Modeling
- Pumped-thermal
- Stratified glycol