scholarly journals Preliminary prospects of a Pumped Thermal Energy Storage (PTES) based on a supercritical CO2 Brayton cycle

2021 ◽  
Author(s):  
Karin Astrid Senta Edel ◽  
František Hrdlička ◽  
Václav Novotný
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Supercritical Co2 ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Brayton Cycle ◽  
Term Energy ◽  
Weather Changes

As part of the change towards a higher deployment of renewable energy sources, which naturally deliver energy intermittently, the need for energy storage systems is increasing. For compensation of disturbance in power production due to inter-day to seasonal weather changes, long-term energy storage is required. In the spectrum of storage systems, one out of a few geographically independent possibilities is the storage of electricity in heat, so-called Carnot-Batteries. This paper presents a Pumped Thermal Energy Storage (PTES) system based on a recuperated supercritical CO2 Brayton cycle. The modelled system provides a round-trip efficiency of 38.9%.

scholarly journals Preliminary prospects of a Carnot-battery based on a supercritical CO2 Brayton cycle

2021 ◽  
Vol 61 (5) ◽  
pp. 644-660
Author(s):  
Karin Rindt ◽  
František Hrdlička ◽  
Václav Novotný
Keyword(s):  
Energy Storage ◽  
Supercritical Co2 ◽  
High Efficiency ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Pressure Ratio ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Round Trip ◽  
Weather Changes

As a part of the change towards a higher usage of renewable energy sources, which naturally deliver the energy intermittently, the need for energy storage systems is increasing. For the compensation of the disturbance in power production due to inter-day to seasonal weather changes, a long-term energy storage is required. In the spectrum of storage systems, one out of a few geographically independent possibilities is the use of heat to store electricity, so-called Carnot-batteries. This paper presents a Pumped Thermal Energy Storage (PTES) system based on a recuperated and recompressed supercritical CO2 Brayton cycle. It is analysed if this configuration of a Brayton cycle, which is most advantageous for supercritical CO2 Brayton cycles, can be favourably integrated into a Carnot-battery and if a similar high efficiency can be achieved, despite the constraints caused by the integration. The modelled PTES operates at a pressure ratio of 3 with a low nominal pressure of 8 MPa, in a temperature range between 16 °C and 513 °C. The modelled system provides a round-trip efficiency of 38.9 % and was designed for a maximum of 3.5 MW electric power output. The research shows that an acceptable round-trip efficiency can be achieved with a recuperated and recompressed Brayton Cycle employing supercritical CO2 as the working fluid. However, a higher efficiency would be expected to justify the complexity of the configuration.

Study of the Melting Behavior in a PCM-Based Thermal Energy Storage

2015 ◽  
Author(s):  
Mohammad Bashar ◽  
Kamran Siddiqui
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Heat Source ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Heat Transfer Process ◽  
Convective Cells

Thermal energy storages are becoming important due to their significance in energy conservation as well as for the uninterrupted supply of thermal energy from renewable energy sources. The latent heat-based thermal energy storage systems utilizing phase change material (PCM) are gaining much attention due to some inherent advantages compared to sensible heat-based storage systems. However, the heat transfer process associated with the phase change in a PCM is complex and not well understood. In the present study, the melting process in a PCM-based thermal storage is experimentally studied. Two different configurations of the heat source were considered; horizontal and U-tube heat sources. The results show that the heat source shape has a significant influence on the solid to liquid phase change process (melting). The results also show that for the horizontal heat source configuration, the solid-liquid interface has a wavy profile, which is attributed to the convective cells in the melted domain of the PCM. These convective cells also influence the heat transfer coefficient, which decreased with an increase in the melted fraction. In U-tube configuration, the heat is non-uniformly transferred to the PCM domain.

Viability Assessment of a Concentrated Solar Power Tower With a Supercritical CO2 Brayton Cycle Power Plant

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Ali Sulaiman Alsagri ◽  
Andrew Chiasson ◽  
Mohamed Gadalla
Keyword(s):  
Energy Storage ◽  
Molten Salt ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Supercritical Co2 ◽  
Solar Power ◽  
Capacity Factor ◽  
Brayton Cycle ◽  
Concentrated Solar Power ◽  
Solar Power Tower

The aim of this study was to conduct thermodynamic and economic analyses of a concentrated solar power (CSP) plant to drive a supercritical CO2 recompression Brayton cycle. The objectives were to assess the system viability in a location of moderate-to-high-temperature solar availability to sCO2 power block during the day and to investigate the role of thermal energy storage with 4, 8, 12, and 16 h of storage to increase the solar share and the yearly energy generating capacity. A case study of system optimization and evaluation is presented in a city in Saudi Arabia (Riyadh). To achieve the highest energy production per unit cost, the heliostat geometry field design integrated with a sCO2 Brayton cycle with a molten-salt thermal energy storage (TES) dispatch system and the corresponding operating parameters are optimized. A solar power tower (SPT) is a type of CSP system that is of particular interest in this research because it can operate at relatively high temperatures. The present SPT-TES field comprises of heliostat field mirrors, a solar tower, a receiver, heat exchangers, and two molten-salt TES tanks. The main thermoeconomic indicators are the capacity factor and the levelized cost of electricity (LCOE). The research findings indicate that SPT-TES with a supercritical CO2 power cycle is economically viable with 12 h thermal storage using molten salt. The results also show that integrating 12 h-TES with an SPT has a high positive impact on the capacity factor of 60% at the optimum LCOE of $0.1078/kW h.

scholarly journals A Review on the Performance Indicators and Influencing Factors for the Thermocline Thermal Energy Storage Systems

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8384
Author(s):  
Wanruo Lou ◽  
Lingai Luo ◽  
Yuchao Hua ◽  
Yilin Fan ◽  
Zhenyu Du
Keyword(s):  
Energy Storage ◽  
Influencing Factors ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Performance Indicators ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Heat Transfer Fluid ◽  
Thermal Energy Storage Systems

Thermal energy storage (TES) system plays an essential role in the utilization and exploitation of renewable energy sources. Over the last two decades, single-tank thermocline technology has received much attention due to its high cost-effectiveness compared to the conventional two-tank storage systems. The present paper focuses on clarifying the performance indicators and the effects of different influencing factors for the thermocline TES systems. We collect the various performance indicators used in the existing literature, and classify them into three categories: (1) ones directly reflecting the quantity or quality of the stored thermal energy; (2) ones describing the thermal stratification level of the hot and cold regions; (3) ones characterizing the thermo-hydrodynamic features within the thermocline tanks. The detailed analyses on these three categories of indicators are conducted. Moreover, the relevant influencing factors, including injecting flow rate of heat transfer fluid, working temperature, flow distributor, and inlet/outlet location, are discussed systematically. The comprehensive summary, detailed analyses and comparison provided by this work will be an important reference for the future study of thermocline TES systems.

scholarly journals Modeling of Combined Lead Fast Reactor and Concentrating Solar Power Supercritical Carbon Dioxide Cycles to Demonstrate Feasibility, Efficiency Gains, and Cost Reductions

2021 ◽  
Vol 13 (22) ◽  
pp. 12428
Author(s):  
Brian T. White ◽  
Michael J. Wagner ◽  
Ty Neises ◽  
Cory Stansbury ◽  
Ben Lindley
Keyword(s):  
Energy Storage ◽  
Heat Exchanger ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Supercritical Co2 ◽  
Solar Power ◽  
Combined Cycle ◽  
Outlet Temperature ◽  
Brayton Cycle ◽  
Concentrating Solar Power

Solar power has innate issues with weather, grid demand and time of day, which can be mitigated through use of thermal energy storage for concentrating solar power (CSP). Nuclear reactors, including lead-cooled fast reactors (LFRs), can adjust power output according to demand; but with high fixed costs and low operating costs, there may not be sufficient economic incentive to make this worthwhile. We investigate potential synergies through coupling CSP and LFR together in a single supercritical CO2 Brayton cycle and/or using the same thermal energy storage. Combining these cycles allows for the LFR to thermally charge the salt storage in the CSP cycle during low-demand periods to be dispatched when grid demand increases. The LFR/CSP coupling into one cycle is modeled to find the preferred location of the LFR heat exchanger, CSP heat exchanger, sCO2-to-salt heat exchanger (C2S), turbines, and recuperators within the supercritical CO2 Brayton cycle. Three cycle configurations have been studied: two-cycle configuration, which uses CSP and LFR heat for dedicated turbocompressors, has the highest efficiencies but with less component synergies; a combined cycle with CSP and LFR heat sources in parallel is the simplest with the lowest efficiencies; and a combined cycle with separate high-temperature recuperators for both the CSP and LFR is a compromise between efficiency and component synergies. Additionally, four thermal energy storage charging techniques are studied: the turbine positioned before C2S, requiring a high LFR outlet temperature for viability; the turbine after the C2S, reducing turbine inlet temperature and therefore power; the turbine parallel to the C2S producing moderate efficiency; and a dedicated circulator loop. While all configurations have pros and cons, use of a single cycle offers component synergies with limited efficiency penalty. Using a turbine in parallel with the C2S heat exchanger is feasible but results in a low charging efficiency, while a dedicated circulator loop offers flexibility and near-perfect heat storage efficiency but increasing cost with additional cycle components.

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