储能技术简介（英文版）_22页_731kb

Thermal Energy Storage Summary

Core Content

Thermal Energy Storage (TES) is a technology that stores thermal energy in various forms—sensible heat, latent heat, and thermo-chemical energy—for later use in heating, cooling, and power generation. TES is particularly relevant in buildings and industrial processes, where thermal energy constitutes about half of the total energy consumption. It helps balance energy demand and supply, reduce peak demand, lower $\mathrm{CO}_{2}$ emissions, and increase energy system efficiency. TES is also important for integrating variable renewable energy sources such as solar and wind.

Main Types of TES Systems

There are three primary types of TES systems:

1. Sensible Heat Storage

   • Stores energy by heating or cooling a medium (e.g., water, sand, molten salts).
   • Water is the most cost-effective medium.
   • Offers storage capacities of 10–50 kWh/t and efficiencies of 50–90%.
   • Requires large volumes due to its low energy density.
   • Commercially available, but requires proper thermal insulation and design to maintain constant discharge temperatures.

2. Latent Heat Storage (PCM)

   • Uses phase change materials (PCMs) to store energy during phase transitions (e.g., solid to liquid).
   • Provides higher storage capacity and more stable discharge temperatures.
   • Storage capacities range from 50–150 kWh/t, with efficiencies between 75–90%.
   • Costs range from €10–50 per kWh.
   • Applications include passive cooling, building and industrial heating, and solar thermal systems.

3. Thermo-Chemical Storage (TCS)

   • Uses chemical reactions (e.g., adsorption, dehydration) to store and release thermal energy.
   • Offers the highest storage capacities (up to 250 kWh/t) and efficiencies (up to nearly 100%).
   • Can store and transport thermal energy over long distances.
   • Costs range from €8–100 per kWh, and are generally higher than other systems.
   • Still under development and demonstration.

Key Applications

• Buildings: TES is used for domestic hot water, space heating, and air conditioning.
• Industry: For process heat, drying, and waste heat recovery.
• Renewables: TES is crucial for concentrating solar power (CSP) plants, where solar heat is stored for later electricity generation.
• District Heating/Cooling: Centralised TES systems are used in large-scale district heating and cooling networks.
• Waste Heat Utilisation: TCS can convert waste heat into usable energy or cold, enhancing energy efficiency in industrial processes.

Economic Performance and Costs

• Sensible Heat Storage: Costs range from €0.1–10 per kWh, depending on size, application, and insulation.
• PCM Storage: Costs are between €10–50 per kWh, with micro-encapsulated PCMs being more expensive.
• TCS Storage: Costs are between €8–100 per kWh, influenced by the need for advanced heat and mass transfer technologies.
• Economic Viability: Depends on the number and frequency of storage cycles. PCM and TCS systems are more economically viable for high-cycle applications.
• Cost Trends: Seasonal storage is less economically attractive than daily or short-term storage due to lower cycle numbers.

Performance and Efficiency

• Sensible Heat Storage: Efficiency ranges from 50–90%, with storage capacity limited by the specific heat of the medium.
• PCM Storage: Offers higher storage capacity and efficiency (75–90%), with energy densities up to 100 kWh/m³.
• TCS Storage: Can reach up to 250 kWh/t with efficiencies up to nearly 100%, suitable for high-temperature applications.
• Storage Periods: Vary from hours to months, depending on the system type and application.
• Power and Discharge Time: Power output and discharge time are interdependent, with higher power requiring more efficient heat transfer mechanisms.

Market Potential and Barriers

• Potential: TES has significant potential in both mature and emerging economies. In Europe, it is estimated that around 1.4 million GWh per year could be saved and 400 million tonnes of $\mathrm{CO}_{2}$ emissions could be avoided.
• Barriers:
  • Cost: High capital and operational costs for PCM and TCS systems.
  • Material Stability: PCMs and TCS materials require further development to ensure long-term performance.
  • Infrastructure: In mature economies, low construction rates of new buildings limit TES deployment.
  • Technology Maturity: While sensible heat systems are well-established, PCM and TCS systems are still in development or demonstration stages.

R&D and Policy Recommendations

• R&D Focus: New materials and techniques for all TES systems, especially for PCM and TCS, are being developed.
• Integration: Encapsulation of PCMs in building materials (e.g., plaster, air vents) is a promising trend.
• Policy Support: Research and development incentives, as well as policies for TES integration in buildings and industrial applications, are essential for wider adoption.
• Investment: Encouraging investment in TES systems can help reduce costs and improve performance over time.

Conclusion

TES is a versatile and promising technology for energy systems, especially in the context of renewable energy integration and energy efficiency improvements. While sensible heat storage is currently the most commercially available and cost-effective option, PCM and TCS systems offer greater efficiency and storage capacity and are critical for future applications. Continued R&D, supportive policies, and investment are necessary to overcome current barriers and expand TES deployment.