A comprehensive review of various types of TES sys- tems, highlighting thermochemical TES, has been presented. Principles of thermochemical TES and recent advances have been reported. The possibility of achieving more compact systems, little energy losses during the storing operation and higher energy densities compared to other types of TES are the most prominent advantages of thermochemical TES sys- tems. Further research is needed to improve understanding of the scientific and engineering characteristics of thermo- chemical TES systems and to help improve various aspects relating to the performance and implementation of these sys- tems. The thermochemical material is a critical component of such systems. The cyclic behavior and degradation of ther- mochemical materials, as well as their cost, availability, du- rability and energy density, are important parameters affect- ing the selection of a thermochemical material. Further re- search is needed on these topics, as well as on design factors, safety, size and efficiency, installation, maintenance and economics for thermochemical TES systems. Also, compre- hensive analyses of these systems based on energy and ex- ergy are needed, as such assessments can assist in design optimization and improvement, and such work is the subject of ongoing research by the authors.
AbstractÑSeveral renewable energies such as wind and solar are intermittent. To increase renewable energy penetration, Electrical EnergyStorage (EES) systems are becoming increas- ingly important. There is an increasing need for wide deploy- ment of EES from generation to distribution systems. This re- quires relevant financial resources, and economics and finance are the important factors to determine if installing EES is prof- itable. Hence, this paper reviews the recent economics and fi- nancial analyses performed for EES in the energy system con- text. The paper begins with examining the EES technologies. Then, the difference between energy economics and finance are explained. The recent EES techno-economic studies and finan- cial studies are reviewed. Under the uncertain economic, financ- ing, and technical environment, it is important to examine EES projects with real options analysis. Finally, the paper concludes with future research directions for EES finance and economics.
The majority of studies carried out on phase change materials have reported poor thermal conductivities , and therefore, the heat transfer performance used in free cooling is low [227, 228]. Promoting the conductivity level to enhance the melting and crystallisation process during the charging and discharging periods has been investigated widely in the literature [229, 230]. A review of theoretical and experimental research to advance the PCM conductivity was presented in . Adding substances with large thermal conductivities; such as copper, aluminium, nickel, stainless steel and carbon fibre in different configurations such as fins, honeycomb, wool, brush, etc.; is considered as one of the effective techniques for enhancing the heat transfer rate (Error! Reference source not found.) . For instance; a eries of axial metal planes perpendicular to the longitudinal pipe to increase the heat transmission between the air and the PCM unit were utilised by Abhat . Application of finned tubes has been reported by Costa et al. . Aluminium fins used inside and outside upper and lower metal box filled with PCM was investigated by Butala and Stritih [217, 234]. Metal matrix structures with PCMs were extensively investigated in [181, 235, 236] to increase the conductivity level with a minimum reduction of energy stored. Furthermore, other benefits such as diminishing the supercooling of salt hydrates and lowering the volume alteration of paraffin can also be realised as well by this method.
Though there has been much debate over the exact defi- nition of smart grid, it actually comprises a broad range of technology solutions that optimize the energy value chain. Depending on where and how a specific utility operates across that chain, it can benefit from deploying certain parts of a smart grid solution set. Smart grid is a large electricity network that uses digital and other ad- vanced technologies to improve efficiency, reliability, and security of the electric system: from large generation, through the delivery systems to electricity consumers and a growing number of distributed-generation and energystorage resources [14-16]. Smart grids co-ordinate the needs and capabilities of all power generators, grid op- erators, end-users, and electricity market stakeholders to operate all parts of the system as efficiently as possible, minimising costs and environmental impacts while maxi- mising system stability, reliability, and resilience. Smart grids are an evolving set of technologies that will be de- ployed at different rates in a variety of settings around the world, depending on local commercial attractiveness, compatibility with existing technologies, regulatory de- velopments, and investment frameworks. Figure 1 de- monstrates the evolutionary character of smart power net- work .
Information in this specific area in the literature is very limited and so evidence for this review has been drawn from expert knowledge and a case study of the Pimlico District Heating Undertaking in central London. Further work in this area is needed, including more extensive qualitative reviews of existing systems to fully understand the issues. However, this research, which provides a detailed quantitative analysis of the thermal energy store in use, was not available for this report and so does not form part of the review. Thermal energy stores offer a number of non- technical advantages. The ability to balance a variable supply and demand ensures that all businesses and residents on the system can be provided efficiently with heat and hot water to meet their needs. A thermal store also offers an emergency buffer to ensure seamless supply in the event of planned or unexpected maintenance. This ensures that the most vulnerable members of the community are also provided with heat and hot water. This can improve living conditions, reducing damp and hence mould growth, and generally improve levels of thermal comfort. In a district heating system such as the Pimlico District Heating Undertaking, heating provision can be adjusted centrally to ensure these standards are maintained even in very cold winters at a fixed and known cost. However, this cost is inflexible and so residents are not able to adjust their expenditure according to their income, but the delivery of more efficient heating or supplementing those on lower
Long-term and compact storage of solar energy is crucial for the eventual transition to a 100% renewable energy economy, and thermochemicalenergystorage system provides a promising solution to achieve long-term energystorage system . The practical applications of different long-term/seasonal sorption heat storagesystems have been widely discussed and analyzed [30, 31]. The most researches are focused on the system energy density, economic considerations, reactor design, and so on. It indicates that long-term/seasonal sorption heat storage technologies are becoming mature and entering the commercialization stage. However, the common thermochemicalenergystorage methods like thermo-chemical/physical sorption based on water and conventional single-stage thermochemical sorption based on ammonia exist some inherent drawbacks, for example, when the ambient temperature is lower than 0 o C, the water-based system will cannot work, and single-stage ammonia-based system cannot produce a relatively high heat output temperature due to the relatively low working pressure caused by the low ambient temperature. Thus, it is urgent to extend the working temperature range by developing advanced thermochemical sorption energystorage technology.
A broad range of types of energystorage technologies and systems exists (see Figure 1). These can be sepa- rated into as chemical, electrical, thermal, thermochemical, mechanical and other classifications. Specific types of energystorage include battery storage, hydrogen energystorage, flywheel energystorage, compressed-gas energystorage, pumped storage, magnetic storage, capacitor storage, chemical storage, thermal energystorage (both sensible and latent), thermochemicalenergystorage, organic and biological energystorage, and others. Although much energystorage is mature and commercially available, new storage technologies are being ac- tively investigated and improvements to existing ones continually sought. Some technologies are both commer- cial at present but also undergoing extensive research, e.g., thermal energystorage .
reasons this transition is based mainly on the exploitation of Photovoltaic Systems (PVS) and Wind Energy Conversion Systems (WECS). However, the inherent issue of both of these technologies are depending directly on the volatile and random weather condition which may lead to the presence of fluctuation in the total produced power. Especially when these energy sources are connected to the network power systems, where this fluctuation can have critical effects on the quality of the transferred power . On the other side, advanced operational techniques and improved control strategies will be required to ensure a safe, stable and reliable operation of the electric power system. The storagesystems are one among such options to improved the quality of electric power based on renewable energy sources, where these systems ensure the storage of the excess energy during overproduction or under consumption periods . For this purpose, several indirect electrical energystoragesystems have been used such as compressed air energystorage system (CAESS), pumped hydro energystorage system (PHESS), flywheel energystorage system (FESS) , battery energystorage system (BESS), hydrogen and Methane or Synthetic Natural Gas (SNG) . In this work the storage of energy via the production of Hydrogen ( H 2 ) and Methane ( CH 4 ) is
Whitelaw (1972) proposed probably one of the early concepts of a flywheel battery electric vehicle (FWBEV) . According to the author the case for local duty vehicle (LDV) was strong as most journeys in cities of US were less than 50 miles. The local duty vehicle (LDV) would have an energystorage system (ESS), a range of 50 miles and maximum speed 50 mph. Since the BEV was very heavy and the ICEV would burn fuel, a flywheel electric LDV was proposed. A FWB with batteries and DC motor propulsion is shown in Fig. 5. The energy removal rate from FWB would be uniform while the batteries will provide for non-uniform power surges. FWB would be charged at home. The FWB would provide average power and batteries would provide peak power. The author says that such a vehicle was possible with technology of that period. According to the review authors, this is a rather unique case as the usual application of FW in BEV consists of the FW providing the power surges. Kugler proposed a system in which the flywheel was integrated to reduce peak current in lead acid battery of BEV . Fig. 6 shows the schematic. The goal was to provide an efficient powertrain for lead acid BEV to have the performance to co-exist with ICEVs safely on public roads. The FW was coupled to a continuous running electric motor which was designed for efficient operation in a narrow speed range. Once started the motor ran continuously even when the EV was stopped and during these phases it charged the FW which acted as a load leveller. The benefits were high power output, mechanical regenerative braking, extended battery life and avoidance of expensive motor controllers. The FW rotated at moderate speeds from 5000 to 10000 rpm and the transmission was hydromechanical, which was popular due to its commercial availability. The author mentions that if such a flywheel battery electric vehicle is not required to undergo a number of closely spaced consecutive accelerations it would be able to compete with ICEV on performance basis.
Superconducting magnetic energystorage (SMES) systems consist of three fundamental parts, the superconducting coil, the cryogenic cooling unit, and a power conditioning system. The coil of SMES is kept at superconductive temperature to meet the superconducting properties of magnetic coil. This storage system has high efficiency in storing DC electric energy. Excess off-peak AC power is converted into direct current and supplied into a superconducting magnetic coil. SMES systems also provide extremely rapid charge/discharge rates. This function can enhance power system stability and improve power supply quality. SMES can damp system oscillations, and improve the transmitting capacity of the power system. Furthermore, it can react to voltage drops faster than any other storage technology available, making sure that the distribution lines are always reliable and secure. SMES systems will improve AC transmission, compensate fluctuating loads, eliminate spinning reserve, provide protection at critical load levels, and act as a backup power supply. The major drawbacks of SMES units are the implementation problems due to the strong magnetic field. For large application the requirement of SMES units will be higher and have environmental issues.
CHAPTER 2 – Literature Review Large CAES plants require a suitable sealed underground cavern for air storage as above ground vessels do not have the scale necessary. It has been found that the mined salt rock caverns are the best option for storage, while aquifers and abandoned mines and depleted oil and gas fields are promising. Salt cavern for CAES operated between . These pressures result in the cavern being contained between deep and a volume of or Varin Vongmanee conducted a study on the renewable energy applications for uninterruptible power supply based on compressed air energystorage system. The study used wind energy to produce the compressed air power via a compressor.
ABSTRACT: Due to rapid increase in demand and environmental pollution necessitates the wind penetration with energystoragesystems play an vital role in both distributed and utility power systems. The benefit of an EnergyStorage System is reduction of operating cost and improvement of voltage profile. So far literature review shows that improper size and placement of energystorage units leads to undesired power system cost as well as the risk of voltage stability, particularly in the case of high renewable energy penetration. This paper provides a solution to solve the above problem, a Hybrid Multi-Objective Particle Swarm Optimization (HMOPSO) method is proposed to minimize the power system cost and improve the system voltage profile by probing optimal sizing and sitting of storage units under consideration of uncertainties in wind power production. The proposed method is tested on both IEEE-30bus and IEEE 118-bus system to perform case studies.
The energy efficiency of buildings is today a prime objective for energy policy at regional, national and international levels. This paper aims to explore how and where phase change materials (PCMs) are used in passive latent heat thermal energystorage (LHTES) systems for thermal management of buildings and making them energy efficient. The review presented here reveals how and where PCMs are used in the cooling systems, how are these LHTES systems related to buildings. This paper investigates previous work on thermal energystorage by incorporating phase change materials (PCMs) in the building envelope. The basic principle, candidate PCMs and their thermo physical properties, incorporation methods, thermal analyses of the use of PCMs in walls, floor, ceiling and window etc. are discussed. All studies have shown that the use of PCMs helps to improve energy performance of buildings, the problems were encountered in heat transfer and the amount of PCM needed for storage. These topics are also worthy of further research.
Thermal energystorage (TES) is becoming a growing concern in modern technology and it has number of applications. Energystorage is essential whenever there is a mismatch between the supply and consumption of energy. Growing energy demands, lack of fossil fuels, and the continuous increase in the level of greenhouse gas emissions are the main driving forces to practice various sources of renewable energy. Due to irregular and unpredictable nature of solar energy; efficient, ermal energystorage devices and methods have to be developed. Among the different possibilities to store energy, systems using Phase Change Materials (PCM) can be preferred for its consistency in latent heat storage. The use of PCM is an effective way of storing thermal energy and has the advantages of having high storage density and the isothermal nature of the storage process. Due to this, the volume of material is reduces and so the cost of the system. But the vity which leads to poor heat transfer so heat transfer enhancement techniques should be used. This paper summarise the selection of thermal energy
A PV/Thermal (PV/T) gatherer is a module in which the PV isn't just delivering power yet in addition fills in as a thermal safeguard. Thus both heat and power are delivered all the while. The schematic of the PV/T advances is exhibited in Fig. 1. The double elements of the PV/T result in a higher general solar powered transformation rate than that of exclusively PV or sunlight based systems, and accordingly empowering more compelling utilization of sun oriented energy. Since the interest for sun oriented heat and sunlight based power are frequently supplementary, it is by all accounts a coherent plan to build up a gadget that can agree to the two requests.
In grid connected photovoltaic systems battery storage banks or storage device are not the critical element, but sometimes it is used to reduced the photovoltaic power fluctuations, perform peak shaving operation and supply power at emergency. [3, 4]. In grid connected photovoltaic system, to maintain the voltage li-ion batteries are used as backup power supply, active and reactive power compensation to maintain the frequency. Hence the system will maintain the balance between supply of active and reactive power and demand at any point of time. Various control technique are used they are the MPPT control, and voltage-frequency . Standalone PV system also uses same control techniques. In standalone PV system the main component are photovoltaic panel module, battery system and local loads for modelling and controlling system. If the output power of the PV is less than or equal to the output power of the system and the storage units are deeply discharged, then whole system is shut down and there will be no power flow . Secondly If the output power of the PV is less than or equal to the output power of the system and the storage units are not deeply discharged (Vs >Vs_min) or Ppv > Po with the storage units not fully charged (Vs<Vs_max), the phush pull dc-dc converter will work in MPPT mode and the dc-dc converter will regulate the DC bus voltage to maintain thepower flow balance of the system. If the PV arrays can not provide enough power to load, the storage units will be discharged to provide the power deficit. If the PV arrays generate more power than load consumes, the superfluous energy will charge the storage units.
Modern society is strongly associated with energy. Elec- tricity and energy help mankind defy nature. Thermal comfort and the ability to preserve food and medications undoubtedly contribute to extending the life expectancy and improving living standards. Over recent decades, fossil fuels combustion has dominated energy produc- tion. Energy generation by fossil fuels offers several advantages, including reliability and scalability (from micro to mega scales). However, the second law of thermodynamics dictates power generation processes by thermodynamic cycles, where the heat rejection to the sink is inevitable . The result is greenhouse gas emis- sion and global warming from the energy-related activi- ties. Recently, generation using renewable energy has been introduced as a favorable alternative. An energy source can be considered renewable if it is naturally replenished and inexhaustible . Renewable energy sources include wind, hydropower, geothermal energy, biomass, and solar power, which is the major source. However, renewable energy sources are associated with unreliability and supply/demand time gap. In other words, unlike the burning of fossil fuels, most renewa- ble energy sources are not always available at the time of demand. Meanwhile, daily and seasonal variation of the solar power can be traced back to the mechanism of the planetary system. The rotation of the earth while it revolves around the sun determines the availability of the solar energy at a particular place on the planet. Thus, it is rather natural that in most cases a storage system is required to realize continuous power supply from the renewable energy source.
All three concepts appear worth pursuing, each has its advantages and particular engineering problems to overcome. In the case of a tube cavity design the main challenge is matching the flux profile to the requirements of the reactor so as to avoid exceeding the maximum temperature limit. Thermal stresses due to local variations in tube wall temperatures would also have to be addressed. Although these problems are common with other thermochemicalsystems, they are exacerbated by the high operating pressure proposed for the ammonia based system. A reflux heat pipe design overcomes these problems and as such may be even better suited to ammonia dissociation than methane reforming reactions carried out at lower pressures. Ensuring correct and reliable operation of a wick mechanism within the reflux heatpipe appears to be the major challenge for this concept. The major challenge with the direct absorption approach is producing a suitably robust window. If this could be achieved, then the windowed pressure vessel design has advantages in the ease with which the internal design could be varied or the catalyst changed during the course of an experimental program.
slowly varying loads and fast load transients –. Storage is an integral part of a hybrid RE/AE power generation system. Capacity-oriented energystorage technologies, such as pumped hydroelectric systems, compressed air energystorage (CAES), and hydrogen storage, generally do not have fast response time and are used for long-term energystorage/release such as managing slow load variations. On the other hand, access-oriented storage devices with fast response time, such as batteries, flywheels, super-capacitors, and superconducting magnetic energystorage (SMES), are used for responding to short time disturbances, such as fast load transients and for power quality issues. References  and  give a comprehensive explanation of the performance, purpose, and promise of different storage technologies. Table I gives a summary of different RE/AE power generation technologies and different energystorage schemes which may be used in hybrid systems. Any combination of the RE/AE power generation technologies, along with proper storage and possibly combined with a conventional generation technology, e.g., a diesel generator could form a hybrid energy system. For example, a hybrid system could have any combination of wind, PV, MH, MT, conventional diesel generator, storage battery, and FC-electrolyzer hydrogen storage in grid- connected or standalone configuration, often referred to as a microgrid. The outputs from various generation sources of a hybrid energy system need to be coordinated and controlled to realize their full benefits. Proper optimization techniques and control strategies are needed for sizing and for power dispatch from the energy sources to make the entire system sustainable to the maximum extent, while facilitating maximum reduction in environmental emissions, and at the same time minimizing cost of energy production. The optimization problem can, therefore, be multi-objective, sometimes with conflicting objectives, and, therefore, complex. In such cases, only a global optimal point, as a trade- off between several local optimal points corresponding to the different objectives, may be achieved. Such optimization problems are difficult (if not impossible) to solve using analytic techniques. Heuristic multi-objective optimization techniques – and goal-oriented multi-agent systems
Renewable energy emerges as an alternative way of generating clean energy. As a result, increasing the use of “green” energy benefits the global environment, making it global concern. This topic relies on a variety of manufacturing and in- stallation industries for its development. As a solution, continuously small and smart grid energysystems appear including renewable energy resources (RES), micro-generators, small energystoragesystems, critical and noncritical loads, forming among them a special type of distributed generation system called the Microgrid.