New compressed air energy storage technology proposed in China – The Global Energy Association

Report on Advancements in Compressed Air Energy Storage (CAES) Technology

Introduction

Researchers from North China Electric Power University have conducted a study aimed at enhancing the efficiency of compressed air energy storage (CAES) systems. These systems play a crucial role in storing surplus energy generated by solar and wind power plants, aligning with the Sustainable Development Goals (SDGs) related to affordable and clean energy (SDG 7) and industry, innovation, and infrastructure (SDG 9).

Background on CAES Technology

CAES operates on the principle of compressing air during periods of excess electricity generation and expanding it to produce energy during peak demand. Traditional CAES systems face inefficiencies due to heat loss during air compression and the absence of heat sources during expansion, leading to reduced energy efficiency.

Innovative Isothermal CAES (ICAES) Technology

To address these challenges, the researchers proposed an isothermal compressed air energy storage (ICAES) technology. This method maintains air temperature at a nearly constant level using liquid pistons, which compress air via a moving liquid with high heat capacity instead of mechanical pistons. This innovation contributes to SDG 7 by improving energy efficiency and sustainability.

• Liquid pistons inject liquid into the working chamber to absorb heat.
• Uniform compression reduces energy loss.
• High heat capacity liquids such as water are utilized.

Technical Challenges and Solutions

Operating under high pressure presents technical difficulties, including the need for large liquid volumes and complex control systems. To overcome these, the researchers introduced a two-stage liquid piston system operating simultaneously in a single flow, enhancing continuous and coordinated air compression.

1. Two sequentially operating liquid piston stages.
2. Simultaneous operation ensures continuous compression.
3. Improved control system stability.

System Design and Operation

The system incorporates a constant-pressure tank capable of storing compressed air at pressures up to 10 MPa. Water regulates pressure by displacement during air intake and release, stabilizing the storage process and enabling energy recovery through liquid movement. The process includes:

• Low- and high-pressure liquid pistons facilitating two-stage air compression.
• Reversed operation during energy generation where expanding air activates the pistons as generators.

Performance and Efficiency

Mathematical modeling indicates that for an accumulation capacity of 200 kW·h and storage pressure up to 10 MPa, the system achieves approximately 68% overall efficiency. This surpasses traditional CAES efficiencies, which rarely exceed 50%. Key benefits include:

• High energy storage density, reducing tank volume by over six times.
• Scalability potential through additional compression stages.

Considerations and Future Prospects

Despite its advantages, the technology consumes energy to maintain constant tank pressure due to liquid movement, slightly reducing overall efficiency. Nonetheless, the system shows significant promise for integration into hybrid energy systems and as a sustainable alternative to large-scale batteries, supporting SDG 7 and SDG 13 (Climate Action).

Conclusion

The advancements in ICAES technology by North China Electric Power University represent a meaningful contribution toward sustainable energy storage solutions. By enhancing efficiency and scalability, this innovation supports global efforts to promote clean, reliable, and affordable energy, in line with the United Nations Sustainable Development Goals.

1. Sustainable Development Goals (SDGs) Addressed or Connected

1. SDG 7: Affordable and Clean Energy
   • The article discusses improving energy storage efficiency for solar and wind power, which are renewable energy sources.
   • The focus on compressed air energy storage (CAES) technology supports the goal of increasing access to reliable and sustainable energy.
2. SDG 9: Industry, Innovation, and Infrastructure
   • The research on advanced isothermal compressed air energy storage technology reflects innovation in industrial processes and infrastructure.
   • Enhancing energy storage systems contributes to resilient infrastructure and promotes sustainable industrialization.
3. SDG 13: Climate Action
   • By improving energy storage efficiency for renewable sources, the technology supports climate action through reduced reliance on fossil fuels and lower greenhouse gas emissions.

2. Specific Targets Under Those SDGs Identified

1. SDG 7 Targets
   • Target 7.2: Increase substantially the share of renewable energy in the global energy mix.
   • Target 7.3: Double the global rate of improvement in energy efficiency.
2. SDG 9 Targets
   • Target 9.4: Upgrade infrastructure and retrofit industries to make them sustainable, with increased resource-use efficiency and greater adoption of clean and environmentally sound technologies.
   • Target 9.5: Enhance scientific research and upgrade the technological capabilities of industrial sectors.
3. SDG 13 Targets
   • Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters.
   • Target 13.2: Integrate climate change measures into national policies, strategies, and planning.

3. Indicators Mentioned or Implied to Measure Progress

1. Energy Storage Efficiency
   • The article provides a specific efficiency value for the new system (~68%) compared to traditional CAES (~50%), implying the use of energy conversion efficiency as an indicator.
2. Energy Storage Density
   • The reduction in tank volume by more than six times indicates an improvement in energy storage density, which can be used as an indicator of system compactness and efficiency.
3. Scalability and Capacity
   • The potential to add additional stages to increase pressure and energy capacity implies indicators related to scalability and energy capacity.
4. Integration with Renewable Energy Sources
   • The system’s role in storing excess energy from solar and wind power plants suggests indicators related to the percentage of renewable energy stored and utilized.

4. Table of SDGs, Targets, and Indicators

Source: globalenergyprize.org