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The performance of a compact phase change material (PCM) solar collector based on latent heat storage was investigated. In this collector, the absorber plate–container unit performs the function of both absorbing the solar energy and storing PCM. The solar energy was stored in paraffin wax, which was used as a PCM, and was discharged to cold water flowing in pipes located inside the wax. The collector's...
This paper presents a comparative study of two energy system analysis models both designed for the purpose of analysing electricity systems with a substantial share of fluctuating renewable energy. The first model (EnergyPLAN) has been designed for national and regional analyses. It has been used in the design of strategies for integration of wind power and other fluctuating renewable energy sources...
The high wind and solar potential along with the extremely high electricity production cost met in the majority of Greek Aegean islands comprising autonomous electrical networks, imply the urgency for new renewable energy sources (RES) investments. To by-pass the electrical grid stability constraints arising from an extensive RES utilization, the adaptation of an appropriate energy storage system...
Pumped hydroelectric energy storage (PHES) is the largest and most mature form of energy storage currently available. However, the capital costs required for PHES are extremely large and the availability of suitable sites is decreasing. Therefore, identifying the remaining sites available for PHES is becoming vital so that the most beneficial location is chosen: in terms of capacity and economics...
A series of microencapsulated phase change materials (MicroPCMs) with n-octadecane as core were successfully fabricated by suspension-like polymerization. The influence of initiator type and polymerization temperature on MicroPCMs were investigated systemically. The morphology of these microcapsules with different copolymer shells and various phase changing material (PCM) contents were observed by...
Storage devices can provide several grid services, however it is challenging to quantify the value of providing several services and to optimally allocate storage resources to maximize value. We develop a co-optimized Compressed Air Energy Storage (CAES) dispatch model to characterize the value of providing operating reserves in addition to energy arbitrage in several U.S. markets. We use the model...
This paper presents the design of flywheel rotor prototypes developed to enhance rural energisation in sub-Saharan Africa. The flywheel rotors are made from locally available fibre and epoxy resin. The profiles were designed using novel shape profiles based on Berger, Porat and Stodola’s designs and manufactured using locally available materials. One of the flywheel rotor profiles was tested on a...
A concept is introduced here for storing utility-scale electrical energy in the form of latent heat. The storage process utilizes a boiling refrigerant at sub-ambient temperatures to freeze a latent heat storage material using electrically driven compressors. Recovery of the latent heat for electrical generation then uses vapor expansion and condensation which essentially reverses the storage process...
In this work the use of compressed air energy storage with air injection (CAES-AI) concept and supercharging with inlet chilling (CAES-IC) concept are discussed and analyzed. The flexibility of these technologies provides unique load management of energy. Performance is calculated for each system and compared. The operating variables in this study are discharge air mass flow, injected air mass flow,...
Thermal energy storage is an expanding field within the subject of renewable energy technologies. After a listing of the different possibilities available for energy storage, this paper provides a comparison of various materials for High Temperature Thermal Energy Storage (HTTS). Several attributes and needs of each solution are listed. One in particular is using the latent heat as one of the most...
The substantial increase in power generation from variable renewable sources has led to renewed interest in energy storage. Pumped hydropower remains the only mature and widely-adopted utility-scale energy storage technology. However, the selection and development of new pumped hydropower sites is heavily influenced by physical constraints such as terrain, as well as non-physical considerations such...
Large scale energy storage may play an increasingly important role in the power generation and distribution sector, especially when large shares of renewable energies will have to be integrated into the electrical grid. Pumped-hydro is the only large scale storage technology that has been widely used. However the spread of this technology is limited by geographic constraints. In the present work,...
A novel type of bulk electricity storage – electrothermal energy storage (ETES) – is presented. The concept is based on heat pump and heat engine technologies utilizing transcritical CO2 cycles, storage of pumped heat in hot water, and ice generation and melting at the cold end of the cycles. The paper first describes the growing need for large scale electrical energy storage and the role of storage...
Thermo-electrical energy storage (TEES) based on thermodynamic cycles is currently under investigation at ABB corporate research as an alternative solution to more consolidated but site-dependent electricity storage technologies such as pump-hydro or compressed air energy storage. During charge electricity is converted into thermal energy by means of a heat pump and during discharge a thermal engine...
The interest in large scale electricity storage (ES) with discharging time longer than 1 h and nominal power greater than 1 MW, is increasing worldwide as the increasing share of renewable energy, typically solar and wind energy, imposes severe load management issues. Thermo-electrical energy storage (TEES) based on thermodynamic cycles is currently under investigation at ABB corporate research as...
Microcapsules containing n-octadecane with different methylmethacrylate (MMA (methyl methacrylate))-based copolymer shells were fabricated by a suspension-like polymerization. Butyl acrylate (BA), butyl methacrylate (BMA), lauryl methacrylate (LMA) and stearyl methacrylate (SMA) were employed as monomers to copolymerize with MMA. Pentaerythritol tetraacrylate (PETRA) was employed as a crosslinking...
Dwindling fossil fuel resources and pressures to reduce greenhouse gas emissions will result in a more diverse range of generation portfolios for future electricity systems. Irrespective of the portfolio mix the overarching requirement for all electricity suppliers and system operators is to instantaneously meet demand, to operate to standards and reduce greenhouse gas emissions. Therefore all electricity...
Due to the rapid increase of wind and photovoltaic generation, flexible storage applications become more important. Electric vehicles are supposed as one option to fill the gap between a fixed energy demand and a stochastic feed in from fluctuating energy sources. But the charging loads will also affect the grid load, since the transport sector contributes considerably to the total energy consumption...
Offshore applications allow to exploit different renewable energy sources (wave, wind, solar) that are complementary each other, due to their statistical yearly distributions.In this paper, we discuss an offshore platform for energy production from renewable energy sources coupled with three energy storage systems. The proposed offshore platforms uses a Compressed Air Energy Storage (CAES) to timely...
Numerical simulations using the computational fluid dynamics (CFD) software ANSYS Fluent were undertaken to characterize the airflow and temperature distribution in a natural convection thermal energy storage refrigerator. The model compared the household refrigerator temperature stability with different phase change materials (PCM) incorporated into the storage compartment. Scenarios investigated...
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