Experimental Study of Nanoengineered Molten Salts as Thermal Energy Storage in Solar Power Plants

2012 ◽  
Author(s):  
Hani Tiznobaik ◽  
Donghyun Shin
Keyword(s):  
Energy Storage ◽  
Physical Properties ◽  
High Temperatures ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Molten Salts ◽  
Solar Power ◽  
Operating Temperature ◽  
Concentrated Solar Power ◽  
Thermo Physical Properties

In a concentrated solar power (CSP), high operating temperature (over 500 °C) is the key for enhancing the efficiency of the system. The operating temperature of the system mainly relies on thermal energy storage (TES) material. Existing TES materials such as mineral oil or paraffin wax cannot be applicable at high temperatures, since these materials are not thermally stable over 400 °C. However, very few materials are suitable and reliable for the high temperatures. Using molten salts (e.g., alkali nitrate, alkali carbonate, alkali chloride, etc.) as thermal energy storage material is an alternative way due to several benefits. They are cheap and environmentally safe compared with the conventional TES materials. They are thermally stable at higher temperatures (over 500 °C). However, their usage is limited due to low thermo-physical properties (e.g. Cp is less than 1.6 J/g°C). The low thermo-physical properties can be improved by dispersing nanoparticles into the salts. In this study, nanomaterials were synthesized by dispersing inorganic nanoparticles into ionic salts. Modulated differential scanning calorimeter (MDSC) was used to measure the heat capacity of the nanomaterials. Scanning electron microscopy (SEM) was used for material characteristic analysis. Hence, the application of the nanomaterials as thermal energy storage in a concentrated solar power was explored.

Investigation of High Temperature Nanofluids for Solar Thermal Power Conversion and Storage Applications

2010 ◽  
Author(s):  
Donghyun Shin ◽  
Byeongnam Jo ◽  
Hyun-eun Kwak ◽  
Debjyoti Banerjee
Keyword(s):  
Heat Capacity ◽  
Thermal Properties ◽  
High Temperature ◽  
Energy Storage ◽  
Physical Properties ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Molten Salts ◽  
Solar Thermal ◽  
Thermo Physical Properties

The aim of this study is to investigate the enhancement of thermal properties of various high temperature nanofluids for solar thermal energy storage application. In concentrating solar power (CSP) systems, the thermo-physical properties of the heat transfer fluids (HTF) and the thermal energy storage (TES) materials are key to enhancing the overall system efficiency. Molten salts, such as alkali nitrates, alkali carbonates, or eutectics are considered as alternatives to conventional HTF to extend the capabilities of CSP. However, there is limited usage of molten salt eutectics as the HTF material, since the heat capacity of the molten salts are lower than that of conventional HTF. Nanofluid is a mixture of a solvent and nanoparticles. Well dispersed nanoparticles can be used to enhance thermo-physical properties of HTF. In this study, silica (SiO2) and alumina (Al2O3) nanoparticles as well as carbon nanotubes (CNT) were dispersed into a molten salt and a commercially available HTF. The specific heat capacity of the nanofluids were measured and applicability of such nanofluid materials for solar thermal storage applications were explored. Measurements performed using the carbonate eutectics and commercial HTF that are doped with inorganic and organic nano-particles show specific heat capacity enhancements exceeding 5–20% at concentrations of 0.05% to 2.0% by weight. Dimensional analyses and computer simulations were performed to predict the enhancement of thermal properties of the nanofluids. The computational studies were performed using Molecular Dynamics (MD) simulations.

Enhanced Heat Capacity of Molten Salt Nano-Materials for Concentrated Solar Power Application

2012 ◽  
Author(s):  
Ramaprasath Devaradjane ◽  
Donghyun Shin
Keyword(s):  
Heat Capacity ◽  
Energy Storage ◽  
Molten Salt ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Molten Salts ◽  
Solar Power ◽  
Storage Temperature ◽  
Nano Materials ◽  
Concentrated Solar Power

Storage of thermal energy using molten salt materials has been widely explored for concentrating solar power. Since these power plants use thermodynamic cycle, the overall system cycle efficiency significantly relies on the thermal energy storage temperature. Therefore, increasing the thermal energy storage temperature and decreasing the amount of material needed can result in reducing the cost of solar energy. Molten salts are stable up to 700°C, relatively cheap, and safe to the environment. However, the heat capacity of the molten salts is typically low (∼1.5 J/gK) compared to other thermal storage materials. The low heat capacity of molten salts can be improved by dispersing nanoparticles. In this study, we synthesized molten salt nanomaterial by dispersing oxide nanoparticles into selected molten salts. Heat capacity measurements were performed using a modulated differential scanning calorimeter. Materials characterization studies were performed using a scanning electron microscopy. Hence, we evaluated the use of the molten salt nanomaterials as thermal energy storage media in concentrated solar power applications. Increase in the specific heat capacity of the molten salt is also demonstrated on addition with Nano materials of specific size and quantity.

Techno-economic assessment of technological improvements in thermal energy storage of concentrated solar power

Solar Energy ◽  
2017 ◽  
Vol 157 ◽  
pp. 552-558 ◽  
Author(s):  
Riezqa Andika ◽  
Young Kim ◽  
Seok Ho Yoon ◽  
Dong Ho Kim ◽  
Jun Seok Choi ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Power ◽  
Economic Assessment ◽  
Concentrated Solar Power ◽  
Technological Improvements

Waste From Metallurgic Industry: A Sustainable High-Temperature Thermal Energy Storage Material for Concentrated Solar Power

2013 ◽  
Author(s):  
Nicolas Calvet ◽  
Guilhem Dejean ◽  
Lucía Unamunzaga ◽  
Xavier Py
Keyword(s):  
Heat Capacity ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Power ◽  
Low Cost ◽  
Concentrated Solar Power ◽  
Storage Material ◽  
Energy Storage Material ◽  
Thermal Energy Storage Material

The ambitious DOE SunShot cost target ($0.06/kWh) for concentrated solar power (CSP) requires innovative concepts in the collector, receiver, and power cycle subsystems, as well as in thermal energy storage (TES). For the TES, one innovative approach is to recycle waste from metallurgic industry, called slags, as low-cost high-temperature thermal energy storage material. The slags are all the non-metallic parts of cast iron which naturally rises up by lower density at the surface of the fusion in the furnace. Once cooled down some ceramic can be obtained mainly composed of oxides of calcium, silicon, iron, and aluminum. These ceramics are widely available in USA, about 120 sites in 32 States and are sold at a very low average price of $5.37/ton. The US production of iron and steel slag was estimated at 19.7 million tons in 2003 which guarantees a huge availability of material. In this paper, electric arc furnace (EAF) slags from steelmaking industry, also called “black slags”, were characterized in the range of temperatures of concentrated solar power. The raw material is thermo-chemically stable up to 1100 °C and presents a low cost per unit thermal energy stored ($0.21/kWht for ΔT = 100 °C) and a suitable heat capacity per unit volume of material (63 kWht/m3for ΔT = 100°C). These properties should enable the development of new TES systems that could achieve the TES targets of the SunShot (temperature above 600 °C, installed cost below $15/kWht, and heat capacity ≥25 kWht/m3). The detailed experimental results are presented in the paper. After its characterization, the material has been shaped in form of plates and thermally cycled in a TES system using hot-air as heat transfer fluid. Several cycles of charge and discharged were performed successfully and the concept was validated at laboratory scale. Apart from availability, low-cost, and promising thermal properties, the use of slag promotes the conservation of natural resources and is a noble solution to decrease the cost and to develop sustainable TES systems.

Energy consumption minimization for a solar lime calciner operating in a concentrated solar power plant for thermal energy storage

2020 ◽  
Vol 156 ◽  
pp. 1019-1027 ◽  
Author(s):  
Pilar Lisbona ◽  
Manuel Bailera ◽  
Thomas Hills ◽  
Mark Sceats ◽  
Luis I. Díez ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Energy Storage ◽  
Power Plant ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Power ◽  
Solar Power Plant ◽  
Concentrated Solar Power
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