scholarly journals Cycle Stability and Hydration Behavior of Magnesium Oxide and Its Dependence on the Precursor-Related Particle Morphology

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 795 ◽  
Author(s):  
Georg Gravogl ◽  
Christian Knoll ◽  
Jan Welch ◽  
Werner Artner ◽  
Norbert Freiberger ◽  
...  
Keyword(s):  
Energy Storage ◽  
Magnesium Oxide ◽  
Waste Heat ◽  
Particle Morphology ◽  
Cycle Stability ◽  
Medium Temperature ◽  
Reaction Couple ◽  
Initial Reactivity

Thermochemical energy storage is considered as an auspicious method for the recycling of medium-temperature waste heat. The reaction couple Mg(OH)2–MgO is intensely investigated for this purpose, suffering so far from limited cycle stability. To overcome this issue, Mg(OH)2, MgCO3, and MgC2O4·2H2O were compared as precursor materials for MgO production. Depending on the precursor, the particle morphology of the resulting MgO changes, resulting in different hydration behavior and cycle stability. Agglomeration of the material during cyclization was identified as main reason for the decreased reactivity. Immersion of the spent material in liquid H2O decomposes the agglomerates restoring the initial reactivity of the material, thus serving as a regeneration step.

scholarly journals Selection Methodology of Potential Sensible Thermal Energy Storage Materials for Medium Temperature Applications

2020 ◽  
Vol 307 ◽  
pp. 01026 ◽  
Author(s):  
Soukaina Hrifech ◽  
Hassan Agalit ◽  
El Ghali Bennouna ◽  
Abdelaziz Mimet
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Waste Heat ◽  
Energy Storage Materials ◽  
Potential Candidate ◽  
Medium Temperature ◽  
Temperature Range ◽  
Natural Rock ◽  
Selection Methodology

Thermal energy storage (TES) component improves the revenue of a concentrating solar power (CSP) plant by allowing more heat to be stored and making the electric energy available during the absence of sunlight. The heat can be stored in three ways (sensible, latent, or thermochemical). The present work aims to identify and select cost-effective sensible TES systems suitable for the medium temperature range (100-300 °C) applications (e.g. Fresnel CSP plants, industrial waste heat recovery, etc.). Based on a literature review, a selection methodology is developed to select potential candidate solid TES media (e.g. natural rock, concrete, sand, etc. ) as filler material in direct or indirect contact with thermal oil, which is used generally as heat transfer fluid (HTF) for this temperature range. The main criteria and steps of this selection methodology are identified and they take into account the different decisive storage properties as thermo-physical and mechanical properties of the solid media. Finally, the potential candidate TES materials are identified for the targeted application and further indoor experimental investigations are briefly presented.

scholarly journals Local Heating Networks with Waste Heat Utilization: Low or Medium Temperature Supply?

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 954 ◽  
Author(s):  
Hanne Kauko ◽  
Daniel Rohde ◽  
Armin Hafner
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Urban Areas ◽  
Waste Heat ◽  
Local Heating ◽  
District Heating ◽  
Heat Pumps ◽  
Hot Water ◽  
Local Network ◽  
Medium Temperature

District heating enables an economical use of energy sources that would otherwise be wasted to cover the heating demands of buildings in urban areas. For efficient utilization of local waste heat and renewable heat sources, low distribution temperatures are of crucial importance. This study evaluates a local heating network being planned for a new building area in Trondheim, Norway, with waste heat available from a nearby ice skating rink. Two alternative supply temperature levels have been evaluated with dynamic simulations: low temperature (40 °C), with direct utilization of waste heat and decentralized domestic hot water (DHW) production using heat pumps; and medium temperature (70 °C), applying a centralized heat pump to lift the temperature of the waste heat. The local network will be connected to the primary district heating network to cover the remaining heat demand. The simulation results show that with a medium temperature supply, the peak power demand is up to three times higher than with a low temperature supply. This results from the fact that the centralized heat pump lifts the temperature for the entire network, including space and DHW heating demands. With a low temperature supply, heat pumps are applied only for DHW production, which enables a low and even electricity demand. On the other hand, with a low temperature supply, the district heating demand is high in the wintertime, in particular if the waste heat temperature is low. The choice of a suitable supply temperature level for a local heating network is hence strongly dependent on the temperature of the available waste heat, but also on the costs and emissions related to the production of district heating and electricity in the different seasons.

scholarly journals Distributed Thermal Energy Storage Configuration of an Urban Electric and Heat Integrated Energy System Considering Medium Temperature Characteristics

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2924
Author(s):  
Wei Wei ◽  
Yusong Guo ◽  
Kai Hou ◽  
Kai Yuan ◽  
Yi Song ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Internal Heat ◽  
Configuration Model ◽  
Electric Heater ◽  
Heat Network ◽  
Release Process ◽  
Medium Temperature ◽  
Temperature Characteristics

Distributed thermal energy storage (DTES) provides specific opportunities to realize the sustainable and economic operation of urban electric heat integrated energy systems (UEHIES). However, the construction of the theory of the model and the configuration method of thermal storage for distributed application are still challenging. This paper analyzes the heat absorption and release process between the DTES internal heat storage medium and the heat network transfer medium, refines the relationship between heat transfer power and temperature characteristics, and establishes a water thermal energy storage and electric heater phase change thermal energy storage model, considering medium temperature characteristics. Combined with the temperature transmission delay characteristics of a heat network, a two-stage optimal configuration model of DTES for UEHIES is proposed. The results show that considering the temperature characteristics in the configuration method can accurately reflect the performance of DTES, enhance wind power utilization, improve the operation efficiency of energy equipment, and reduce the cost of the system.

scholarly journals An Experimental Study of the Decomposition and Carbonation of Magnesium Carbonate for Medium Temperature Thermochemical Energy Storage

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1316
Author(s):  
Daniel Mahon ◽  
Gianfranco Claudio ◽  
Philip Eames
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Energy Storage ◽  
Magnesium Carbonate ◽  
Experimental Results ◽  
Future Research ◽  
Medium Temperature ◽  
Different Temperatures ◽  
Decomposition Enthalpy ◽  
Co2 Atmosphere

To improve the energy efficiency of an industrial process thermochemical energy storage (TCES) can be used to store excess or typically wasted thermal energy for utilisation later. Magnesium carbonate (MgCO3) has a turning temperature of 396 °C, a theoretical potential to store 1387 J/g and is low cost (~GBP 400/1000 kg). Research studies that assess MgCO3 for use as a medium temperature TCES material are lacking, and, given its theoretical potential, research to address this is required. Decomposition (charging) tests and carbonation (discharging) tests at a range of different temperatures and pressures, with selected different gases used during the decomposition tests, were conducted to gain a better understanding of the real potential of MgCO3 for medium temperature TCES. The thermal decomposition (charging) of MgCO3 has been investigated using thermal analysis techniques including simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC), TGA with attached residual gas analyser (RGA) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (up to 650 °C). TGA, DSC and RGA data have been used to quantify the thermal decomposition enthalpy from each MgCO3.xH2O thermal decomposition step and separate the enthalpy from CO2 decomposition and H2O decomposition. Thermal analysis experiments were conducted at different temperatures and pressures (up to 40 bar) in a CO2 atmosphere to investigate the carbonation (discharging) and reversibility of the decarbonation–carbonation reactions for MgCO3. Experimental results have shown that MgCO3.xH2O has a three-step thermal decomposition, with a total decomposition enthalpy of ~1050 J/g under a nitrogen atmosphere. After normalisation the decomposition enthalpy due to CO2 loss equates to 1030–1054 J/g. A CO2 atmosphere is shown to change the thermal decomposition (charging) of MgCO3.xH2O, requiring a higher final temperature of ~630 °C to complete the decarbonation. The charging input power of MgCO3.xH2O was shown to vary from 4 to 8136 W/kg with different isothermal temperatures. The carbonation (discharging) of MgO was found to be problematic at pressures up to 40 bar in a pure CO2 atmosphere. The experimental results presented show MgCO3 has some characteristics that make it a candidate for thermochemical energy storage (high energy storage potential) and other characteristics that are problematic for its use (slow discharge) under the experimental test conditions. This study provides a comprehensive foundation for future research assessing the feasibility of using MgCO3 as a medium temperature TCES material. Future research to determine conditions that improve the carbonation (discharging) process of MgO is required.

scholarly journals Flexible Electricity Dispatch of an Integrated Solar Combined Cycle through Thermal Energy Storage and Hydrogen Production

Thermo ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 106-121
Author(s):  
Miguel Ángel Reyes-Belmonte ◽  
Alejandra Ambrona-Bermúdez ◽  
Daniel Calvo-Blázquez
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Hydrogen Generation ◽  
Combined Cycle ◽  
Medium Temperature ◽  
Cost Of Electricity ◽  
Demand Curves ◽  
Hydrogen Plant ◽  
Demand Coverage

In this work, the flexible operation of an Integrated Solar Combined Cycle (ISCC) power plant has been optimized considering two different energy storage approaches. The objective of this proposal is to meet variable users’ grid demand for an extended period at the lowest cost of electricity. Medium temperature thermal energy storage (TES) and hydrogen generation configurations have been analyzed from a techno-economic point of view. Results found from annual solar plant performance indicate that molten salts storage solution is preferable based on the lower levelized cost of electricity (0.122 USD/kWh compared to 0.158 USD/kWh from the hydrogen generation case) due to the lower conversion efficiencies of hydrogen plant components. However, the hydrogen plant configuration exceeded, in terms of plant availability and grid demand coverage, as fewer design constraints resulted in a total demand coverage of 2155 h per year. It was also found that grid demand curves from industrial countries limit the deployment of medium-temperature TES systems coupled to ISCC power plants, since their typical demand curves are characterized by lower power demand around solar noon when solar radiation is higher. In such scenarios, the Brayton turbine design is constrained by noon grid demand, which limits the solar field and receiver thermal power design.

Design and Optimization of Integrated Distributed Energy Systems for Off-grid Buildings

2021 ◽  
pp. 1-27
Author(s):  
Jian Zhang ◽  
Heejin Cho ◽  
Pedro Mago
Keyword(s):  
Energy Storage ◽  
Optimal Design ◽  
Power Systems ◽  
Thermal Energy ◽  
Waste Heat ◽  
Carbon Dioxide Emission ◽  
Energy Systems ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Distributed Energy

Abstract Off-grid concepts for homes and buildings have been a fast-growing trend worldwide in the last few years because of the rapidly dropping cost of renewable energy systems and their self-sufficient nature. Off-grid homes/buildings can be enabled with various energy generation and storage technologies, however, design optimization and integration issues have not been explored sufficiently. This paper applies a multi-objective genetic algorithm (MOGA) optimization to obtain an optimal design of integrated distributed energy systems for off-grid homes in various climate regions. Distributed energy systems consisting of renewable and non-renewable power generation technologies with energy storage are employed to enable off-grid homes/buildings and meet required building electricity demands. In this study, the building types under investigation are residential homes. Multiple distributed energy resources are considered such as combined heat and power systems (CHP), solar photovoltaic (PV), solar thermal collector (STC), wind turbine (WT), as well as battery energy storage (BES) and thermal energy storage (TES). Among those technologies, CHP, PV, and WT are used to generate electricity, which satisfies the building's electric load, including electricity consumed for space heating and cooling. Solar thermal energy and waste heat recovered from CHP are used to partly supply the building's thermal load. Excess electricity and thermal energy can be stored in the BES and TES for later use. The MOGA is applied to determine the best combination of DERs and each component's size to reduce the system cost and carbon dioxide emission for different locations. Results show that the proposed optimization method can be effectively and widely applied to design integrated distributed energy systems for off-grid homes resulting in an optimal design and operation based on a trade-off between economic and environmental performance.

Using Molding to Fabricate Stable Salt Structures for Thermochemical Energy Storage

2021 ◽  
Author(s):  
Adam Gladen ◽  
Fardad Azarmi
Keyword(s):  
Energy Storage ◽  
Sintering Temperature ◽  
Hydration Reaction ◽  
Half Cycle ◽  
Cycle Stability ◽  
Manufacturing Techniques ◽  
Hygroscopic Salts ◽  
Fabrication Parameters ◽  
Molded Sample ◽  
Stable Structures

Abstract The present work investigates using a molding technique to fabricate stable salt structures for thermochemical energy storage. Two type of salts were investigated: pure MgSO4 and a blend of 53% CaCl2 with 47% MgSO4. These salts were mixed with two common binders and hot pressed. Various post-hot-pressing conditions were considered including the debinding temperature, whether the sample was sintered, and the sintering temperature. The samples were subjected to combined hydration and thermal cycling. The hydration reaction was monitored by measuring the relative humidity. The samples were visibly inspected for changes between each half cycle. The results indicate that molding can result in stable structures. All the samples of 53wt%CaCl2+47%wtMgSO4 and one sample of pure MgSO4 retained their integrity through the course of cycling. Of the samples that did not retain their integrity through cycling, the results show that fabrication parameters can be used to improve the cycle stability of the molded sample. The hydration data shows that, for the samples that retained their structure, stable hydration rates were achieved. This indicates that the structure stabilized. These results show the feasibility of using molding or similar manufacturing techniques to fabricate a stable structure of hygroscopic salts for thermochemical-based, thermal energy storage.

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