Performance analysis of an Injera baking machine by using solar energy

Thermal performance study of a solar-coupled phase changes thermal energy storage system for ORC power generation

Chapter 7 - Solar thermal energy storage

The efficient utilization of solar energy technology is significantly enhanced by the application of energy storage, which plays an essential role. Nowadays, a wide variety of applications deal with energy storage. Due to the intermittent nature of solar radiation, phase change materials are excellent options for use in several types of solar energy systems. This overview of the relevant literature thoroughly discusses the applications of phase change materials, including solar collectors, solar stills, solar ponds, solar air heaters, and solar chimneys. Despite the complexity of their availability and high costs, phase change materials are utilized in the majority of solar energy techniques because of the considerable technical improvements they provide. While numerous studies have investigated the progress of phase change materials used in solar energy applications such as photovoltaic systems, it is vital to understand the conceptual knowledge of employing phase change materials in various types of solar thermal energy systems. Investigations into the use of phase change materials in solar applications for the purpose of storing thermal energy are still being carried out to upgrade the overall performance. This paper briefly reviews recently published studies between 2016 and 2023 that utilized phase change materials as thermal energy storage in different solar energy systems by collecting more than 74 examples from the open literature. This study focuses on demonstrating the maturity of phase change materials and their integration into solar energy applications. Based on the findings, proposals for new research projects are made.

There is broad scientific agreement that anthropogenic greenhouse gases are contributing to global climate change and that carbon dioxide (CO2) is the primary contributor. Coal-based electricity generation produces over 30% of U.S. CO2 emissions; however, coal is also an available, secure, and low cost fuel that currently provides roughly half of U.S. electricity. As the world transitions from the existing fossil fuel-based energy infrastructure to a sustainable energy system, carbon dioxide capture and sequestration (CCS) will be a critical technology to allow continued use of coal-based electricity in an environmentally acceptable manner. Post-combustion amine absorption and stripping is one leading CO2 capture technology that is relatively mature, available for retrofit, and amenable to flexible operation. However, standard system designs have high capital costs and can reduce plant output by approximately 30% due to energy requirements for solvent regeneration (stripping) and CO2 compression. A typical design extracts steam from the power cycle to provide CO2 capture energy, reducing net power output by 11–40%. One way to reduce the CO2 capture energy penalty while developing renewable energy technologies is to provide some or all CO2 capture energy with a solar thermal energy system. Doing so would allow greater power plant output when electricity demand and prices are the highest. This study presents an initial review of solar thermal technologies for supplying energy for CO2 capture with a focus on high temperature solar thermal systems. Parabolic trough and central receiver (power tower) technology appear technically able to supply superheated steam for CO2 compression or saturated steam for solvent stripping, but steam requirements depend strongly on power plant and CO2 capture system design. Evacuated tube and compound parabolic collectors could feasibly supply heat for solvent stripping. A parabolic trough system supplying the energy for CO2 compression and solvent stripping at a gross 500 megawatt-electrical coal-fired power plant using 7 molal MEA-based CO2 capture would require a total aperture area on the order of 2 km2 or more if sized for an average direct normal solar insolation of 561 W/m2. The solar system’s capital costs would be roughly half that of the base coal-fired plant with CO2 capture. This analysis finds that irrespective of capital costs, relatively high electricity prices are required for additional electricity sales to offset the operating and maintenance costs of the solar thermal system, and desirable operational periods will be further limited by the availability of sunlight and thermal storage. At CO2 prices near 50 dollars per metric ton of CO2, bypassing CO2 capture yields similar operating economics as using solar energy for CO2 capture with lower capital cost. Even at high CO2 prices, any operating profit improvement from using solar energy for CO2 capture is unlikely to offset system capital costs. For high temperature solar systems such as power towers and parabolic troughs, direct electricity generation is likely a more efficient way to use solar energy to replace output lost to CO2 capture energy. However, low temperature solar systems might integrate more seamlessly with solvent stripping equipment, and more rigorous plant design analysis is required to definitively assess the technical and economic feasibility of using solar energy for CO2 capture.

The energy source for electricity generation in Indonesia is mostly supplied from fossil energy, but this energy source will run out in the next 20 years. Various researches are now leading to the development of alternative energy sources such as solar energy. There are two kinds of solar energy utilization technologies, namely solar thermal energy technology and solar photovoltaic energy. Thermal solar energy in Indonesia is generally used for the drying process of agricultural and marine products, while photovoltaic solar energy is used to meet electricity needs, especially in remote areas. Most solar panels are installed permanently at a fixed angle. This causes the solar panels to be unable to absorb solar heat optimally because the sun is always moving. Therefore we need a tool that can move solar panels to follow the direction of the sunlight. The tool used is known as a solar tracker panel. This tool consists of an Arduino Uno as a microcontroller, an LDR (light dependent resistor) as a sensor and a servo motor to drive the solar panels. This tool is double axis, so it can (up and down) as well (to the left and right). The purpose of making this tool is to optimize the absorption of sunlight into the solar panels in order to further reduce the cost of spending electricity PLN. This type of research used in this research is quantitative research with a descriptive approach. The test results proved to be more efficient than the patented on-site solar panels. This tool is applied as a source of energy for water pumps and also for other items such as lamps,.etc

Potential evaluation of hybrid nanofluids for solar thermal energy harvesting: A review of recent advances

This paper reviews the optimization and control of thermal energy storage systems. Emphasis is given to thermal storage applied to combined heat and power systems, building systems, and solar thermal power systems. The paper also discusses how applications of thermal storage can benefit the chemical industry. Optimization of the design and control of thermal storage systems improves plant performance and improves the management of transient energy loads in a variety of applications. In order to maximize the benefits of thermal storage, it is necessary to include advanced multivariate constrained controls, such as model predictive control. Thermal storage also increases system flexibility, allowing the incorporation of intermittent renewable energy sources. The flexibility of thermal storage will play an increasingly important role as utilities implement smart grid technology with time-of-use electricity pricing. Lastly, thermal energy storage improves system economics by reducing required equipment sizes, improving efficiency, and reducing equipment wear.

Influence of accelerated thermal charging and discharging cycles on thermo-physical properties of organic phase change materials for solar thermal energy storage applications

In 2016, space heating (SH) and domestic hot water (DHW) heating for Canadian residential buildings accounted for 11% of Canada's total greenhouse gas (GHG) emissions. To drastically decrease the GHG emissions from the residential sector, solar thermal energy can be used to fulfill the SH and DHW needs of residential buildings. A major challenge for solar energy use in Canada is the timing mismatch between the solar radiation received and the SH needs of homes. A seasonal thermal energy store bridges this gap by storing thermal energy and discharging it when the demand arises. Sand can be used as the medium in thermal energy storage, but no research has yet been published demonstrating the feasibility or efficiency of a sand-based seasonal thermal energy store (SSTES) for a residential building. A full-scale research house with a solar combisystem and an SSTES has been built in Ottawa, Canada, to evaluate this novel technology. This thesis documents and analyzes a year-long experiment that was performed at the research house to assess whether the solar combisystem and SSTES can fulfill over 90% of the house’s annual SH and DHW heating needs with solar energy. It also presents the development of a 3D, conduction-only numerical model of the heat transfer in and around the SSTES that is validated with the data from the year-long experiment. Validated numerical models allow various design scenarios to be tested and optimized with less time and economic investment. The experimental results show that solar energy fulfilled 70% of the house’s annual SH and DHW heating loads (i.e. solar fraction=70%). The principal reason for the lower-than-expected solar fraction was the SSTES’s high rate of heat loss (twice the expected rate). Its storage efficiency (i.e. heat extraction/heat injection) was only 20%. Analysis of the experimental data shows one side of the SSTES loses heat faster than the other sides. It is hypothesized that the SSTES’s insulation has become partially degraded; the numerical model was modified to reflect this. The final model has been validated through comparison to the experimental data using several key metrics that are presented and analyzed in this work.

Experimental study on storage performance of packed bed solar thermal energy storage system using sintered ore particles

Energy, exergy and sustainability analysis of a photovoltaic-thermal solar system with nano-enhancement and thermal energy storage integration

To optimize the utilization of solar energy in the latent heat thermal energy storage (LHTES) system, this study conducts exergy analysis on a paraffin-solar water shell and tube unit established in the literature to evaluate the effects of different inclination angles, inlet temperatures, original temperatures, and fluid flow rates on the exergy and exergy efficiency. Firstly, the thermodynamic characteristics of the water and the natural convection effects of the paraffin change with different inclination angles. When the inclination angle of the heat storage tank is less than 30°, the maximum exergy inlet rate rises from 0 to 144.6 W in a very short time, but it decreases to 65.7 W for an inclination angle of 60°. When the inclination angle is increased from 0° to 30°, the exergy efficiency rises from 86% to 89.7%, but it decreases from 94% to 89.9% with the inclination angle from 60° to 90°. Secondly, under the condition that the inclination angle of the energy storage unit is 60°, although increasing the inlet temperature of the solar water enhances the exergy inlet and storage and reduces the charging time, it increases the heat transfer temperature difference and the irreversible loss of the system, thus reducing the exergy efficiency. As the inlet water temperature is increased from 83 to 98 °C, the exergy efficiency decreases from 94.7% to 93.6%. Moreover, increasing the original temperature of the LHTES unit not only reduces the exergy inlet and storage rates but also decreases the available work capacity and exergy efficiency. Finally, increasing the inlet water flow rate increases the exergy inlet and storage rates slightly. The exergy efficiency decreases from 95.6% to 93.3% as the unit original temperature is increased from 15 to 30 °C, and it is enhanced from 94% to 94.6% as the inlet flow rate is increased from 0.085 to 0.34 kg/s with the unit inclination angle of 60°. It is found that arranging the shell and tube unit at an inclination angle is useful for improving the LHTES system’s thermal performance, and the exergy analysis conducted aims to reduce available energy dissipation and exergy loss in the thermal storage system. This study provides instructions for solar energy utilization and energy storage.

Wearable solar energy management based on visible solar thermal energy storage for full solar spectrum utilization

This paper presents a review of the storage of solar thermal energy with phase‐change materials to minimize the gap between thermal energy supply and demand. Various types of systems are used to store solar thermal energy using phase‐change materials. The performance of latent heat storage is dependent on the shape and size of the fins, the orientation and design of the storage unit, and its position. The efficiency of a solar thermal collector integrated with phase change material depends on the inclination of the collector, the position of the phase change material, and its thermo‐physical properties. The study of the thermo‐physical properties of various phase‐change materials and their effects is the focus of this paper.

The demand for cooling in Gulf region is the direct effect of its high atmospheric temperature. Around 60% of the electricity demand in GCC is for cooling purpose. The main source of cooling and air-conditioning in these countries are conventional electric compression cycle, which leads to the increase in the GHG emission, directly in the form of leaked gases from these systems and indirectly in the form of fossil fuel used for the production of the used electricity for these systems. Solar energy in general and solar thermal energy specifically can be a promising and sustainable solution to the cooling and air-conditioning requirement for the buildings in Qatar and GCC. Absorption cooling and air-conditioning is a mature and promising technology with respect to its efficiency and results on the industrial scale. However, the use of technology with solar thermal energy is new in the market. In this paper, the feasibility analysis of solar thermal technology has been done for the cooling, heating and hot water requirement of a commercial building in Doha, Qatar. Heating and hot water requirement for winter and cooling requirement for summer season were calculated and used as a load. Solar thermal collectors (STC) were used as the main source of thermal energy collection form sunlight. Along with STC, thermally driven adsorption chiller was designed to fulfill the cooling requirement in the summer season. The design and selection of the different components and parameters such as Solar thermal collector area, storage tank size, adsorption chiller etc. have been done in detail. The result, obtained for building's energy demand and its supply from the designed solar thermal system, gives a clear sign for the successful implementation of this technology.