Energy Storage Technologies

🔋Energy Storage Technologies Unit 9 – Thermal Energy Storage: Types and Methods

Thermal energy storage (TES) is a game-changing technology that captures and stores heat or cold for later use. It decouples energy supply and demand, improving efficiency and flexibility in energy systems. TES is crucial for integrating renewable sources and reducing reliance on fossil fuels. TES comes in three main types: sensible heat, latent heat, and thermochemical storage. Each type uses different materials and methods to store thermal energy. From water tanks and molten salts to phase change materials and chemical reactions, TES offers diverse solutions for various applications.

What's Thermal Energy Storage?

  • Thermal energy storage (TES) involves capturing and storing thermal energy for later use
  • Enables the storage of heat or cold to be utilized at a different time than when it was generated
  • Decouples the supply and demand of thermal energy, allowing for more efficient and flexible energy systems
  • Can be achieved through various methods such as sensible heat storage, latent heat storage, and thermochemical storage
  • Plays a crucial role in reducing energy consumption, improving energy efficiency, and integrating renewable energy sources
  • Helps to balance energy supply and demand by storing excess thermal energy during off-peak periods and releasing it during peak demand
  • Offers the potential to reduce greenhouse gas emissions by minimizing the reliance on fossil fuels for heating and cooling applications

Why It Matters

  • TES is essential for the efficient utilization of renewable energy sources (solar thermal, geothermal)
  • Helps to reduce the mismatch between energy supply and demand, improving the overall efficiency of energy systems
  • Enables the integration of intermittent renewable energy sources by storing excess energy for later use
  • Contributes to the reduction of peak energy demand, leading to cost savings and reduced strain on energy infrastructure
  • Facilitates the implementation of district heating and cooling systems, improving energy efficiency in urban areas
  • Supports the decarbonization of the heating and cooling sectors by reducing the reliance on fossil fuels
  • Enhances energy security by providing a reliable and dispatchable source of thermal energy

Types of Thermal Energy Storage

  • Sensible heat storage
    • Utilizes the heat capacity of a storage medium to store thermal energy
    • Involves heating or cooling a material without changing its phase
    • Common storage media include water, rock, concrete, and molten salts
  • Latent heat storage
    • Exploits the phase change of a material to store thermal energy
    • Utilizes the latent heat absorbed or released during phase transitions (solid-liquid, liquid-gas)
    • Phase change materials (PCMs) such as paraffin wax, salt hydrates, and fatty acids are commonly used
  • Thermochemical storage
    • Relies on reversible chemical reactions to store and release thermal energy
    • Utilizes the energy absorbed or released during chemical reactions
    • Offers high energy storage densities and long-term storage capabilities
    • Examples include metal hydrides, carbonates, and hydroxides

Key Methods and Technologies

  • Sensible heat storage systems
    • Water tanks and aquifers for low-temperature applications
    • Rock beds and concrete for high-temperature applications
    • Molten salt storage for concentrated solar power plants
  • Latent heat storage systems
    • Encapsulated PCMs for building applications (walls, ceilings, floors)
    • Shell-and-tube heat exchangers with PCMs for industrial processes
    • PCM-enhanced heat sinks for electronic cooling
  • Thermochemical storage systems
    • Adsorption and absorption systems using zeolites, silica gel, or salt hydrates
    • Chemical heat pumps utilizing metal hydrides or ammonia-based reactions
    • Calcium looping processes for high-temperature applications
  • Hybrid storage systems
    • Combining sensible and latent heat storage for improved performance
    • Integration of thermochemical storage with sensible or latent heat storage

Materials Used in TES

  • Sensible heat storage materials
    • Water: Widely used for low-temperature applications due to its high specific heat capacity
    • Rock and concrete: Suitable for high-temperature applications due to their thermal stability
    • Molten salts: Utilized in concentrated solar power plants for their high heat capacity and thermal stability
  • Latent heat storage materials (PCMs)
    • Organic PCMs: Paraffin wax, fatty acids, and polyethylene glycol
    • Inorganic PCMs: Salt hydrates, metallic alloys, and eutectic mixtures
    • Encapsulation materials: Polymers, metals, and ceramics for containing PCMs
  • Thermochemical storage materials
    • Adsorbents: Zeolites, silica gel, and activated carbon
    • Salt hydrates: Calcium chloride, magnesium chloride, and lithium bromide
    • Metal hydrides: Magnesium hydride, sodium alanate, and lithium hydride
  • Heat transfer fluids
    • Water, glycol solutions, and thermal oils for low-temperature applications
    • Molten salts, liquid metals, and supercritical fluids for high-temperature applications

Applications and Case Studies

  • Building heating and cooling
    • Passive solar design with thermal mass (concrete, brick) for energy storage
    • PCM-enhanced building envelopes (walls, ceilings) for thermal regulation
    • Seasonal thermal energy storage (STES) for district heating and cooling
  • Industrial processes
    • Waste heat recovery and storage for later use in industrial processes
    • High-temperature TES for solar thermal power generation (molten salt storage)
    • TES for process heat in food processing, textile, and chemical industries
  • Renewable energy integration
    • Concentrating solar power (CSP) plants with molten salt storage for dispatchable electricity generation
    • Geothermal energy storage using aquifers or rock beds
    • Integration of TES with wind or solar photovoltaic systems for energy management
  • Transportation
    • TES for thermal management in electric vehicles (battery cooling, cabin heating)
    • Thermal energy recovery and storage in internal combustion engines
    • Latent heat storage for refrigerated transport and cold chain logistics

Efficiency and Performance Factors

  • Storage capacity: Amount of thermal energy that can be stored in the system
    • Depends on the storage medium, system design, and operating conditions
    • Higher storage capacity allows for longer discharge durations and increased flexibility
  • Charge and discharge rates: Speed at which thermal energy can be stored and released
    • Influenced by the heat transfer characteristics of the storage medium and system design
    • Higher charge and discharge rates enable faster response times and improved system dynamics
  • Heat transfer efficiency: Effectiveness of heat transfer between the storage medium and the heat transfer fluid
    • Depends on the thermal properties of the materials, surface area, and flow conditions
    • Higher heat transfer efficiency reduces thermal losses and improves overall system performance
  • Thermal losses: Undesired heat transfer from the storage system to the surroundings
    • Influenced by the insulation quality, surface area, and temperature difference
    • Minimizing thermal losses is crucial for maintaining the stored energy over time
  • Cycling stability: Ability of the storage system to maintain its performance over repeated charge-discharge cycles
    • Affected by material degradation, corrosion, and thermal stresses
    • High cycling stability ensures long-term reliability and reduces maintenance requirements
  • Cost-effectiveness: Economic viability of the TES system considering capital costs, operating costs, and energy savings
    • Depends on factors such as material costs, system complexity, and energy prices
    • Optimizing cost-effectiveness is essential for the widespread adoption of TES technologies

Future Developments and Challenges

  • Advanced materials research
    • Development of novel PCMs with higher energy storage densities and improved thermal properties
    • Exploration of nanomaterials and composite materials for enhanced heat transfer and stability
    • Investigation of thermochemical storage materials with higher energy densities and reversibility
  • System integration and optimization
    • Integration of TES with renewable energy sources and existing energy infrastructure
    • Optimization of system design and control strategies for improved efficiency and flexibility
    • Development of advanced heat exchanger designs and heat transfer enhancement techniques
  • Thermal management and control
    • Advancements in thermal insulation materials and techniques to minimize heat losses
    • Development of intelligent control systems for optimal charging and discharging of TES systems
    • Integration of predictive models and real-time monitoring for improved system performance
  • Techno-economic analysis and policy support
    • Comprehensive assessment of the economic feasibility and environmental benefits of TES systems
    • Development of supportive policies and incentives to encourage the adoption of TES technologies
    • Identification of potential market opportunities and business models for TES applications
  • Standardization and certification
    • Establishment of standardized testing and performance evaluation methods for TES systems
    • Development of certification schemes to ensure the quality and reliability of TES products
    • Collaboration among industry stakeholders to promote interoperability and compatibility of TES components


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© 2024 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.