Dynamic load scheduling based on virtual energy storage and solar power prediction in smart grid

Improved thermal energy storage of nanoencapsulated phase change materials by atomic layer deposition

Cost-minimised design of a highly renewable heating network for fossil-free future

Constructing the multi-energy complementary system with wind power, photovoltaic and concentrating solar power (CSP) as well as battery is an effective way to facilitate renewable energy integration. Coordinately optimization of battery and thermal energy storage capacities in CSP can help to reduce the investment cost and improve the renewable energy utilization. In this paper, a mixed integer linear programming model is formulated and system constraints such as renewable energy curtailment rate and operation constraints of each power plant are considered. The nonlinear thermoelectric conversion of CSP is approximated by the piecewise linearization method. Given the data of annual wind and solar power outputs as inputs, the optimal battery and thermal energy storage capacities which maximizes the equivalent uniform annual profit of system are obtained. Case studies are tested on a demonstration project of multi-energy complementary system in North China with a 300MW wind plant, 300MW photovoltaic solar station, 50MW CSP station and 50MW Li-ion battery. It is verified that the optimal capacities of battery and thermal energy storage are 194MWh and 1280MWht. In case studies, sensitivity of the system profit to battery capacity is also analyzed. The testing results validate the effectiveness of the proposed method.

Use of encapsulated zinc particles in a eutectic chloride salt to enhance thermal energy storage capacity for concentrated solar power

n-Eicosane-Fe3O4@SiO2@Cu microcapsule phase change material and its improved thermal conductivity and heat transfer performance

Solar multiple (SM) and thermal storage capacity are two key design parameters for revealing the performance of direct steam generation (DSG) solar power tower plant. In the case of settled land area, SM and thermal storage capacity can be optimized to obtain the minimum levelized cost of electricity (LCOE) by adjusting the power generation output. Taking the dual-receiver DSG solar power tower plant with a given size of solar field equivalent electricity of 100 MWe in Sevilla as a reference case, the minimum LCOE is 21.77¢/kWhe with an SM of 1.7 and a thermal storage capacity of 3 h. Besides Sevilla, two other sites are also introduced to discuss the influence of annual DNI. When compared with the case of Sevilla, the minimum LCOE and optimal SM of the San Jose site change just slightly, while the minimum LCOE of the Bishop site decreases by 32.8% and the optimal SM is reduced to 1.3. The influence of the size of solar field equivalent electricity is studied as well. The minimum LCOE decreases with the size of solar field, while the optimal SM and thermal storage capacity still remain unchanged. In addition, the sensitivity of different investment in sub-system is investigated. In terms of optimal SM and thermal storage capacity, they can decrease with the cost of thermal storage system but increase with the cost of power generation unit.

Optimizing the thermal energy storage performance of shallow aquifers based on gray correlation analysis and multi-objective optimization

Viability of hybrid and alkali-activated slag materials for thermal energy storage: Analysis of the evolution of mechanical and thermal properties

Coordinating thermal energy storage capacity planning and multi-channels energy dispatch in wind-concentrating solar power energy system

PV–Enhanced Solar Thermal Power

High thermal storage capacity phase change microcapsules for heat transfer enhancement through hydroxylated-silanized nano-silicon carbide

Implementation of thermal energy storage (TES) systems into a building and facilities improves the performance of the heating/cooling system by reducing energy waste. Thermal performance of a TES relies on the thermophysical properties of the thermal storage medium (TSM). In the present study, a novel two-step selection model has been implemented to choose the best TSM to improve TES system performance. Various types of thermal storage media are investigated considering phase change materials combined with nanoparticles. Thermal storage capacity, heat storage rate, and thermal storage efficiency have been considered as the main selection parameters in a hierarchy method. A significant contribution of this work is the development of a modelling methodology which can be used as a material selection process or tool. It enables the selection of the most efficient TES on a case-by-case basis. This TSM selection technique adds new understanding of selection tools, and new modelling capabilities to this field. It works with a variety of building cooling/heating loads, and helps minimize the environmental impact of extracting/releasing heat to the ground in geothermal applications. The TSM includes PCM and various PCMs have been considered with a melting range of 5–11℃. A material database of 90 different nano phase change materials (nanoPCMs) has been generated by considering ten types of TSMs and nine types of nanoparticles. First, a 2D numerical model has been used to investigate the heat transfer characteristics of the TSM filled in a cylindrical enclosure with a height of 5 cm and a diameter of 1.2 cm. Fourteen different nanoPCMs were selected to further study based on their thermal storage capacity, heat storage rate, and improvement coefficient (ξ) and implemented into a second numerical model (3D) to calculate the thermal storage efficiency of the designed underground TES system with a height of 20 m and a diameter of 1.5 m. Finally, a building heating/cooling load has been implemented in the numerical model to evaluate the performance of the final designed system on the ground temperature throughout five years of operation. The ground temperature and its variation have an effect on the performance of the ground source heat pump. After five years of operation simulation of the no-PCM system, the ground temperature has increased by 1.78℃ to 9.78℃. However, by adding PCM and nanoPCM, the average temperature reduced to 8.95℃ and 8.72℃, respectively.

Researchers are committed to develop robust and responsive technologies for renewable energy sources to avert from reliance on fossil fuels, which is the main cause of global warming and climate change. Solar energy based renewable energy technologies are valued as an important substitute to bridge gap between energy demand and generation. However, due to varying and inconsistent nature of solar energy during weather fluctuations, seasonal conditions and night times, the complete utilisation of technology is not guaranteed. Therefore, thermal energy storage (TES) system is considered as an imperative technology to be deployed within solar energy systems or heat recovery systems to maximise systems efficiency and to compensate for varying thermal irradiance. TES system can capture and store the excess amount of thermal energy during solar peak hours or recover from systems that would otherwise discard this excess amount of thermal energy. This stored energy is then made available to be utilised during solar off peak hours or night times. Phase change material (PCM) based TES system is appraised as a viable option due to its excellent adoption to solar and heat recovery systems, higher thermal storage density and wide range of materials availability. However, due to its low thermal conductivity (≅ 0.2 W/mK), the rapid charging and discharging of TES system is a challenge. Therefore, there is a need for efficient and responsive heat exchange mechanism to boost the heat transfer within PCM. In this study, transient analysis of two-dimensional computational model of vertical shell and tube based TES system is conducted. Commercial grade paraffin (RT44HC) is employed in shell as thermal storage material due to its higher thermal storage density, thermo-physical stability and compatibility with container material. Water is made to flow in tubes as heat transfer fluid. In this numerical study, the parametric investigations are performed to determine the enhancement in charging rate, discharging rate and thermal storage capacity of TES system. The parametric investigations involve geometrical orientations of tubes in shell with and without fins, inlet temperature and volume flow rate of HTF. It is evident from numerical results that due to increase in effective surface area for heat transfer by vertical fins, the charging and discharging rate of paraffin based TES system can be significantly increased. Due to inclusion of vertical fins, conduction heat transfer is dominant mode of heat transfer in both charging and discharging processes. Furthermore, vertical fins do not restrict natural convection or buoyancy driven flow as compared to horizontal fins. Similarly, the inlet temperature has a noticeable impact on both charging and discharging process. In melting process, the sensible enthalpy is boosted due to rise in inlet temperature and thus the whole system thermal storage capacity is enhanced. Likewise, the effect of volume flow rate of HTF on charging and discharging rate is moderate as compared to inlet temperature of HTF. The numerical results are validated by experimental results. To conclude, these findings present an understanding into how to increase charging and discharging rate of TES system so as to provide feasible design solutions for widespread domestic and commercial utilisation of TES technology.

Investigation on the thermal energy storage characteristics in a spouted bed based on different nozzle numbers

Kinetics study on inhibiting battery thermal runaway using an inorganic phase change material with a super high thermochemical storage capacity