New hybrid energy storage system offers green solution for grid stability and waste heat recovery

Researchers develop a high-performance system integrating compressed air energy storage, high-temperature thermal storage, and supercritical CO₂ cycles to boost energy efficiency and economic viability.

As the world shifts toward renewable energy, the challenge of grid instability caused by the intermittency of wind and solar power has become more pressing. A research team from Northeast Electric Power University has proposed a novel solution: a hybrid cogeneration system that combines Compressed Air Energy Storage (CAES) with High-Temperature Thermal Energy Storage (HTTES) and a supercritical CO₂ Brayton cycle.

The study, published in the journal ENGINEERING Energy (formerly Frontiers in Energy), provides a comprehensive thermodynamic and economic assessment of this integrated system, demonstrating its potential to provide stable electricity and domestic hot water while significantly reducing carbon emissions.

Bridging the Energy Gap Traditional CAES systems often rely on fossil fuel combustion to heat air before it enters turbines, leading to environmental concerns. The new hybrid system replaces the combustor with an HTTES unit, which uses cost-effective materials like refractory concrete to store energy as sensible heat. This allow the system to store both high-quality electricity via air compressors and fluctuating, low-quality renewable energy through thermal resistance heating.

Maximizing Performance through Integration To further enhance efficiency, the researchers integrated a supercritical CO₂ Brayton cycle to recover waste heat from the final stage of the air turbine. This "cascade utilization" of energy ensures that thermal energy typically lost to the environment is instead used to generate additional power.

Key performance metrics of the system under design conditions include:

• Energy Storage Density (ESD): 5.49~kWh/m³.
• Round-Trip Efficiency (RTE): 58.39%.
• Exergy Efficiency: 61.85%.
• Economic Viability: A dynamic payback period of just 4.81 years and an internal rate of return (IRR) of 23.51%.

Optimizing for the Future The team utilized the NSGA-II multi-objective optimization algorithm to refine the system's design. After optimization, the system's energy storage density nearly doubled to 9.97~kWh/m³, while the exergy efficiency increased to 63.84%.

"This integrated approach not only improves energy conversion but also addresses the economic and environmental challenges of large-scale storage," said Prof. Ruifeng Cao, the corresponding author of the study. "Our findings provide a clear roadmap for designing more adaptable and cost-effective energy systems."

JOURNAL: ENGINEERING Energy (formerly Frontiers in Energy)

DOI: 10.1007/s11708-024-0972-2

Article Link: https://link.springer.com/article/10.1007/s11708-024-0972-2

Cite this article: Cao R, Li W, Ni H, et al. Comprehensive assessment and optimization of a hybrid cogeneration system based on compressed air energy storage with high-temperature thermal energy storage. Front. Energy, 2025, 19(2): 175-192. https://doi.org/10.1007/s11708-024-0972-2