Lecture 10: Energy Storage and Conversion Systems PDF

0640-484 Renewable Energy and Sustainability LECTURE 10: ENERGY STORAGE AND CONVERSION SYSTEMS Dr. Aisha Al-Obaid Chemical Engineering Department College of Engineering and Petroleum Kuwait University Lecture 10: Energy Storage and Conversion Syste...

0640-484 Renewable Energy and Sustainability LECTURE 10: ENERGY STORAGE AND CONVERSION SYSTEMS Dr. Aisha Al-Obaid Chemical Engineering Department College of Engineering and Petroleum Kuwait University Lecture 10: Energy Storage and Conversion Systems 3 Why Do We Need Energy Storage Systems? The share of renewable sources in the power generation mix had hit an all- time high of 30% in 2021. According to the International Renewable Energy Agency (IRENA), the share of non-fossil fuel-based generation sources, i.e., renewable energy sources should increase to 57% globally by 2030 in order to meet the Paris Agreement’s target of keeping the average global temperature rise well below 2 °C. Renewable sources, notably solar photovoltaic and wind, are estimated to contribute to two-thirds of renewable growth. However, these renewable sources are intermittent and variable, for example: Solar panels may be inefficient in cloudy weather Wind turbines may be inefficient in calm weather Renewable energy sources may produce excess energy, causing the system to over-load at times. Reference 7 Lecture 10: Energy Storage and Conversion Systems 4 Why Do We Need Energy Storage Systems? 1 The inconsistency and intermittent nature of renewable energy will introduce operational risks to power systems, e.g., frequency and voltage stability issues. Thus, to account for these intermittencies and to ensure a proper balance between energy generation and demand, energy storage systems (ESSs) are regarded as the most realistic and effective choice. ESSs has great potential to optimize energy management and control energy spillage. Energy storage can store energy during off-peak periods and release energy during high-demand periods, which is beneficial for the joint use of renewable energy and the grid. The ESS used in a power system is generally independently controlled, with three working status of charging, storage, and discharging. References 6 and 7 Lecture 10: Energy Storage and Conversion Systems 5 Energy Storage Technologies Although energy storage technologies can be categorized by storage duration, response time, and function, the most popular method is by the form of energy stored, broadly classified into 5 categories: Reference 1 Lecture 10: Energy Storage and Conversion Systems 6 Energy Storage Technologies Reference 7 Lecture 10: Energy Storage and Conversion Systems 7 The Top Ten Countries by Installed Capacity of ESSs (FYI) > & & Reference 1 Lecture 10: Energy Storage and Conversion Systems 8 Energy Storage Technologies: Mechanical Mechanical energy storage as a mature technology features the largest installed capacity in the world. In a Mechanical ESS, electric energy is converted into mechanical energy to be stored. Mechanical ESS mainly includes: Pumped hydro system (PHS) Flywheel energy system (FES) Compressed air energy system (CAES) Gravity energy storage system (GES) References 6 and 7 Lecture 10: Energy Storage and Conversion Systems 9 Energy Storage Technologies: Mechanical References 6 and 7 Lecture 10: Energy Storage and Conversion Systems 10 Mechanical ESSs : Pumped Hydro System (PHS) Pumped Hydro System is the most widely implemented Mechanical ESS with a huge energy capacity, long storage period and high efficiency. By the end of 2019, the total installed capacity of PHS reached up 171.0 GW, which accounts for 93.4% of the total installed ESS capacity worldwide. A typical PHS system consists of: Two large reservoirs located at various elevations. A unit to pump water from the lower reservoir to the higher reservoir. A turbine to generate electricity as water flows downwards from the upper reservoir to the lower reservoir. References 6 and 7 Lecture 10: Energy Storage and Conversion Systems 11 Mechanical ESSs : Pumped Hydro System (PHS) Charging: During off-peak hours: The electrical energy from the power source is turned into mechanical energy, which is then converted into potential energy by pumping and storing water from lower reservoir to higher reservoir through pump. Discharging: During peak hours: The stored water from the upper reservoir is released back into the lower reservoir, rotating the turbines and generating electricity through generators. Reference 7 Lecture 10: Energy Storage and Conversion Systems 12 Mechanical ESSs : Pumped Hydro System (PHS) By transferring water between two reservoirs at different elevations, it stores and generates energy in the form of potential energy. The volume of water stored in the reservoirs and the difference in elevation between them determine the amount of energy stored. The table shows some of the PHS plants in the world (FYI). Reference 7 Lecture 10: Energy Storage and Conversion Systems 13 Mechanical ESSs : Pumped Hydro System (PHS) Pros Mature technology, capable of storing huge amounts of energy High overall efficiency (around 70–80%) Fast response time Inexpensive way to store energy Cons Few potential sites Environmental impacts Requires a significant huge water source Reference 8 Lecture 10: Energy Storage and Conversion Systems 14 Mechanical ESSs : Pumped Hydro System (PHS) (FYI) A plant is being built in the Hatta region of the United Arab Emirates (UAE) with a water reservoir suitable for PHES uses. When completed in 2025, the project will have: A capacity of 250 MW /1,500 MWh It will have a lifespan of 80 years A turnaround efficiency of 78.9% A response to demand for energy within 90 seconds Reference 7 https://www.pv-magazine.com/2023/09/14/dubais-250-mw-1500-mwh-pumped-storage-project-nearing-completion/ Lecture 10: Energy Storage and Conversion Systems 15 Mechanical ESSs : Pumped Hydro System (PHS) (FYI) The project is assisting the UAE in meeting its objective of depending on 25% renewable energy resources in their energy mix by 2030, and 75% clean energy production by 2050. Dubai Electricity and Water Authority’s (DEWA) has finished building 74% of its pumped-storage hydroelectric power plant site, according to a company statement. The project in Hatta will be completed by the first half of 2025. The facility will also store electricity from the 5 GW Mohammed bin Rashid Al Maktoum Solar Park. Mohammed bin Rashid Al Maktoum Solar Park. PHS plant Hatta Lecture 10: Energy Storage and Conversion Systems 16 Mechanical: Gravity Energy Storage System (GES) Working principle of gravity power module: Charging: Surplus energy is stored during the charging cycle by pumping water to elevate the piston. Discharging: excess energy is released during the discharging cycle by pushing water through the turbine, which spins the generator and provides required energy. Reference 7 Lecture 10: Energy Storage and Conversion Systems 17 Mechanical ESSs : Compressed Air Energy Storage System (CAES) CAES is an energy storage technology that stores energy by compressing the air. The amount of stored energy depends on the volume of the storage container as well as the pressure and temperature at which the air is stored. A typical CAES system consists of the following five major components: A motor that drives a compressor A multi-stage compressor that compresses the air A container or cavity for storing compressed air, which can be underground caverns or porous reservoirs A turbine train that includes both high and low-pressure turbines A generator which returns electrical energy to the grid Reference 7 Lecture 10: Energy Storage and Conversion Systems 18 Mechanical ESSs : Compressed Air Energy Storage System (CAES) Charging: During off-peak hours: Surplus electricity is used to drive the motor, generating mechanical energy and driving the multistage compressor. The compressor raises atmospheric air pressure, which is then stored in the underground cavern Discharging: During peak hours: The compressed air stored in the cavern is used to drive the pressure turbines, which convert compressed air energy into mechanical energy, which is then used to drive a generator that generates electricity Reference 7 Lecture 10: Energy Storage and Conversion Systems 19 Mechanical ESSs : Adiabatic Compressed Air Energy Storage System (A-CAES) During operation, the available electricity is used to compress air into a cavern at depths of hundreds of meters and at pressures up to 100 bar. At high pressures, the compressor discharge temperature can exceed 600 °C. Thermal energy is passed from the compressed air to a Thermal Energy Storage (TES) systems (based on thermo-oil, molten salt, etc.). The cooled air is then injected under pressure into the cavern. When the stored energy is needed, this compressed air is used to generate power in a turbine while simultaneously recovering the heat from the thermal storage. Reference 7 Lecture 10: Energy Storage and Conversion Systems 20 Mechanical: Flywheel Energy Storage System (FES) The Flywheel Energy Storage (FES) system is a mechanical energy storage device that stores the energy in the form of mechanical energy by utilizing the kinetic energy, i.e., the rotational energy of a massive rotating cylinder. The five essential components of a modern flywheel system: A flywheel Magnetic bearings An electrical motor/generator A power conditioning unit ! A vacuum chamber losses s · G 55 % 855 05. Reference 7 Lecture 10: Energy Storage and Conversion Systems 21 Mechanical: Flywheel Energy Storage System (FES) Charging: During the charging cycle, the motor draws power from the grid to rotate the flywheel system at high speeds and stores kinetic energy. The energy is stored in the flywheel by keeping the rotating body at a constant speed. - Discharging mode: During the discharging process, the flywheel releases energy and drives the machine as a generator. The generator convert the kinetic energy stored in the flywheel back to electrical energy. References 4 and 7 Lecture 10: Energy Storage and Conversion Systems 22 Mechanical: Flywheel Energy Storage System (FES) Pros: Low maintenance and long lifespan: up to 20 years Almost no carbon emissions Me I Fast response time - No toxic components & Cycle stability (a long life of providing full charge–discharge cycles) charry &f Used for application that requires frequent cycling. discharg Cons: High acquisitions cost energy is Short operation duration - * -g - Low storage capacity & High self-discharge (3–20% per hour) is %10 St - Reference 8 Lecture 10: Energy Storage and Conversion Systems 23 Energy Storage Technologies => Belgi Reference 1 Lecture 10: Energy Storage and Conversion Systems 24 Thermal Energy Storage G (TES) Systems -- o 5/d-5 G TES systems are specially designed to store heat energy by cooling, heating, melting, condensing, or vaporizing a substance. - Depending on the operating temperature range, the materials are stored at - high - or low temperatures in an insulated repository Later, the energy recovered from these materials is used for various residential and industrial applications, such as space heating or cooling, - - hot water production, or electricity generation, depending on the operating - temperature range. & - - - C ↑ $175 -din - Reference 7 Lecture 10: Energy Storage and Conversion Systems 25 Thermal ESSs: Sensible - Heat Storage is - - = 11 x S &D Sensible Heat Storage (SHS) is the most widely deployed TES system. It => - stores heat energy by raising the temperature of a solid or liquid by ΔT without affecting itsC phase. The primary benefit of SHS is that charging and discharging of the storage - material are completely reversible and have unlimited - life cycles. However, the major drawbacks of SHS systems are their massive storage space requirements and large initial capital investment. Reference 7 Lecture 10: Energy Storage and Conversion Systems 26 Thermal ESSs: Sensible Heat Storage: Molten Salt Molten salts are suitable candidates for liquid sensible heat storage at temperatures exceeding 100 °C. The term “molten salt” refers to a liquid formed by the fusing of an inorganic salt. Molten salts have many advantages, including high boiling temperatures, low viscosity, low vapor pressure, and large volumetric heat capacities. Molten salt is commonly utilized in concentrated solar facilities that include parabolic mirrors or sun-tracking mirrors. Reference 7 Lecture 10: Energy Storage and Conversion Systems 27 Thermal ESSs: Sensible Heat Storage: Molten Salt Reference 7 Lecture 10: Energy Storage and Conversion Systems 28 # Thermal ESSs: Sensible Heat Storage: Molten Salt Charging and Discharging Cycles (explaining the previous figure): In the solar field, synthetic oil is employed as heat transfer fluid, while molten salt is used as a storage material. ↑ During the charging cycle, the synthetic oil is heated by circulating it through the solar field. A part of the heated synthetic oil is directed to the oil-to-salt heat exchanger, where it cools down by exchanging thermal energy with the molten salt. This heated salt is stored in a hot storage tank. During the discharge cycle, the heat is transferred from the heated salt to the synthetic oil in the heat exchanger, generating enough thermal energy to generate superheated steam, which powers the turbine and generates electricity. Reference 7 Lecture 10: Energy Storage and Conversion Systems 29 Thermal ESSs: Latent = Heat Storage System Latent heat storage (LHS) system utilizes the amount of heat absorbed or released when the storage material undergoes a phase change. The ability of storage material to undergo phase change at a constant temperature is critical to the performance of LHS systems. Solid-liquid transitions are commonly used in Latent Thermal Energy Storage (TES) systems Reference 7 Lecture 10: Energy Storage and Conversion Systems 30 Thermal ESSs: Temperature-Energy Diagram - Temperature-Energy diagram for heating and cooling of a substance: Point O: material in the solid phase Region O–A : sensible heating of material due to heat addition Region A–B: conversion of material from solid phase to liquid phase due to melting Region B–C: sensible heating of liquid Region C– D: liquid-to vapor phase change Region D–E: sensible heating of the vapor Reference 7 Lecture 10: Energy Storage and Conversion Systems 31 Thermal ESSs: Latent Heat Storage System: Phase Change Material Thermal Energy Storage (PCM-TES) This method involves the use of various phase change materials depending on the required temperature range. It is an effective way of storing thermal energy and has the advantages of high thermal energy storage density and the isothermal nature of the storage process. There are large numbers of PCMs that melt and solidify at a wide range of temperatures, making them suitable for a wide range of applications. Good PCMs should be able to withstand a large number of thermal cycles (freezing and melting) with no loss. Reference 7 Lecture 10: Energy Storage and Conversion Systems 32 Thermal ESSs: Latent Heat Storage System: Phase change material thermal energy storage (PCM-TES) The charging cycle: When heat is supplied to the PCM, it continues to absorb heat without significantly increasing its temperature until it undergoes a phase transition from solid to liquid. During the discharging period: As the ambient temperature around the liquid PCM falls, it undergoes a phase change from liquid to the solid phase, releasing the stored latent - heat. PCMs can store 5–14 times more energy per unit volume than the traditional sensible storage materials such as water, rocks and other solids. PCMs can store and release heat energy at a nearly constant temperature, which is another benefit. However, the low thermal conductivities of phase change materials pose a significant barrier to their use in large scale applications. Reference 7 Lecture 10: Energy Storage and Conversion Systems 33 Thermal ESSs: Latent Heat Storage System: Phase change material thermal energy storage (PCM-TES) To be considered for commercial applications, a PCM should satisfy the properties listed in the following table: Reference 7 Lecture 10: Energy Storage and Conversion Systems 34 Thermal ESSs: Latent Heat Storage System: Phase change material thermal energy storage (PCM-TES) (FYI) The Table below shows melting points and heat of fusions of some organic and inorganic phase change materials Reference 7 Lecture 10: Energy Storage and Conversion Systems 35 Thermal ESSs: Thermochemical Energy Storage (TCES) System Thermochemical Energy Storage (TCES) System is a method of indirectly storing heat energy. Heat is not directly stored as in SHS or LHS, but is absorbed and released during dissociation/association of molecular bonds in an entirely reversible chemical reaction. It stores heat energy by utilizing the enthalpy of reaction ΔH. The amount of heat stored depends on: The type and amount of storage material The enthalpy of the reaction The degree of conversion Reference 7 Lecture 10: Energy Storage and Conversion Systems 36 Thermal ESSs: Thermochemical Energy Storage (TCES) System Charging: During an endothermic reaction (a positive change of ΔH) heat is stored by the dissociation of reactive components into individual components. Discharging: The stored energy is released through exothermic reactions (ΔH < 0) by combining the individual components. Lecture 10: Energy Storage and Conversion Systems 37 Thermal ESSs: Thermochemical Energy Storage (TCES) System TCES system, among the available TES systems, offers promising advantages, including: Higher energy densities compared to sensible or phase change materials storage A wide operating temperature range No heat leakage Long-term storage. The major drawback of this system is its increased complexity. Reference 7 Lecture 10: Energy Storage and Conversion Systems 38 Energy Storage Technologies Reference 1 Lecture 10: Energy Storage and Conversion Systems 39 Electrical Energy Storage (EES) System The EES systems store energy in an electric field without converting the electrical energy into other forms of energy. EES systems are classified into two types: Electrostatic energy storage systems: The capacitors and supercapacitors Magnetic energy storage systems: The superconducting magnetic energy storage (SMES) Reference 7 Lecture 10: Energy Storage and Conversion Systems 40 Electrical ESSs: Capacitors When charged, a capacitor stores electrical energy utilizing an electrostatic field. It is made up of two closely spaced metal plates separated by a dielectric layer of non-conducting material. During the operation, as a voltage source is applied across the metal plates, one plate gets charged with electricity while the opposite sign induces the other plate. Reference 7 Lecture 10: Energy Storage and Conversion Systems 41 Electrical ESSs: Supercapacitors Supercapacitors, also known as electric double-layer capacitors (EDLC) or ultracapacitors, are made up of two conductor electrodes, an electrolyte, and a separator. They store energy in the form of an electrostatic field created by a continuous direct current voltage supplied between two electrodes. The two electrodes made of activated carbon provide a larger surface area, resulting in higher energy density. A porous membrane separates the two electrodes, allowing charged ions in the electrolyte to move freely while preventing electronic contact between them. Reference 7 Lecture 10: Energy Storage and Conversion Systems 42 Electrical ESSs: Supercapacitors Supercapacitors are used in applications requiring many rapid charge/discharge cycles, rather than long-term compact energy storage. The use of supercapacitors for wind energy applications was demonstrated by integrating short-term energy storage devices to smooth out quick wind-induced power variations. The disadvantages of supercapacitor energy storage systems include low energy density and high operational costs. Reference 7 Lecture 10: Energy Storage and Conversion Systems 44 Electrical ESSs: Superconducting Magnetic Energy Storage (SMES) System The SMES system stores energy in the magnetic field created by a direct flow current in a coil made of superconducting material. SMES is made up of three major components: A superconducting coil A control and power conditioning system A cryogenically cooled refrigerator Low temperature is needed so the metal becomes a superconductor and thus has virtually no resistive losses as it produces the magnetic field. Reference 7 Lecture 10: Energy Storage and Conversion Systems 45 Electrical ESSs: Superconducting Magnetic Energy Storage (SMES) System To retain its superconducting condition, the superconducting coil is cryogenically chilled to a very low temperature using a refrigeration system. During the charging phase, the flow of current increases in the superconducting coil while decreasing during the discharging cycle. The control and power conditioning system regulates the electrical energy of the SMES system during the charging and discharging cycle according to the output power requirements SMES have great performance characteristics for applications in power systems such as rapid response (in milliseconds), high power output (multi-MW) and high efficiency. Reference 7 Lecture 10: Energy Storage and Conversion Systems 46 Electrical ESSs: Superconducting Magnetic Energy Storage (SMES) System SMES are mostly applied to improve power quality (e.g., balancing fluctuating load), and improve power system stability. Even though SMES systems are commercially available, the number of SMES sold remains quite low, owing mostly to their high initial cost in comparison to other mature technologies. Pros: Capable of partial and deep discharge Fast response time No environmental hazard Cons: High energy losses (~12% per day) Very expensive in production and maintenance Reduced efficiency due to the required cooling process References 7 and 8 Lecture 10: Energy Storage and Conversion Systems 48 Energy Storage Technologies In the next lecture note, we’ll cover Chemical, Electrochemical, and hybrid energy storage systems. Reference 1 0640-484 Renewable Energy and Sustainability LECTURE 11: ENERGY STORAGE AND CONVERSION SYSTEMS – PART 2 Dr. Aisha Al-Obaid Chemical Engineering Department College of Engineering and Petroleum Kuwait University Lecture 11: Energy Storage and Conversion Systems – Part 2 3 Topics Covered Energy Storage Systems (Electrochemical, Chemical, and Hybrid) Energy Storage Systems Comparison Energy Storage Systems Selection Criteria Lecture 11: Energy Storage and Conversion Systems – Part 2 4 Energy Storage Technologies In this lecture note, we’ll cover Chemical, Electrochemical, and hybrid energy storage systems. Reference 1 Lecture 11: Energy Storage and Conversion Systems – Part 2 5 Electrochemical Energy Storage (EcES) System Electrochemical energy storage system is the most widely used energy storage system. It is mainly categorized into two types: Battery energy storage (BES) systems, in which charge is stored within the electrodes. Flow battery energy storage (FBES) systems: in which charge is first stored within the fuel and then externally fed on to the surface of the electrodes. Apart from these two traditional energy storage technologies, extensive research is being conducted in electrochemical storage capabilities to meet the growing demand for lightweight, compact, and flexible electronic devices. Reference 7 Lecture 11: Energy Storage and Conversion Systems – Part 2 6 Classification of Electrochemical ESS Reference 7 Lecture 11: Energy Storage and Conversion Systems – Part 2 7 Battery energy storage (BES) system Schematic diagram of battery energy storage system. The key components in this case are batteries, which are used to store electrical energy in the form of chemical energy. Lecture 11: Energy Storage and Conversion Systems – Part 2 8 Battery energy storage (BES) system Batteries are electrochemical devices that convert chemical energy into electrical energy. They are composed of a number of cells, each of which has three basic components: Two electrodes, namely, an anode and a cathode And an electrolyte. They are broadly categorized into two groups: primary and secondary. Primary batteries are intended to be single-use batteries, with the chemical, once consumed, cannot be recharged. Secondary batteries are designed to be recharged. Secondary batteries are classified as lead-acid (LA), lithium-ion, nickel-cadmium (Ni-Cd), sodium sulphur (NaS), sodium-ion (Na-ion), and metal air batteries, depending on the material of the electrodes and electrolyte. Reference 7 Lecture 11: Energy Storage and Conversion Systems – Part 2 9 Battery energy storage (BES) system For rechargeable batteries: The anode provides electrons, and the cathode absorbs electrons. The separator guarantees the insulating relationship between the two electrodes. The electrolyte is responsible for transporting ions between the cathode and the anode. While electrons flow through the external circuit. Lecture 11: Energy Storage and Conversion Systems – Part 2 10 Lead-Acid Batteries Lead-acid batteries are the most popular and oldest electrochemical energy storage device (invented in 1859). Lead-acid batteries are the most cost- effective option among available rechargeable battery technologies. It is made up of : Two electrodes: Anode: a metallic sponge lead (Pb) Cathode: a lead dioxide (PbO2) An electrolyte made up of 37% sulphuric acid (H2SO4) and 63% water. A porous separator that separates electrodes and prevents electrons from flowing directly from anode to cathode. The voltage of the lead-acid battery is about 2 V, and the lifetime is about 3–12 years References 6 and 7