Recent developments in renewable energy assisted cold thermal energy storage air conditioning systems

The accelerating global fears about climate change and the imperative to reduce energy consumption have spurred a growing interest in sustainable and energy-efficient cooling solutions. Traditional air conditioning systems, reliant on fossil fuels and grid electricity, put a significant burden on energy resources and add to greenhouse gas emissions. To address these challenges, there has been an increase in research and development activities in recent years that are centered on the integration of renewable energy sources with advanced Cold Thermal Energy Storage (CTES) technologies into air conditioning systems. This review article comprehensively explores the latest advancements in renewable energy-assisted CTES air conditioning systems. It begins by elucidating the principles and significance of CTES, discussing its various forms, including phase change materials (PCMs), ice storage, and advanced materials. The integration of PCMs, particularly advanced nano-enhanced or composite PCMs, has been shown to improve thermal storage capacity by approximately 20–30 %, although their long-term stability and environmental impacts require further investigation. Subsequently, the article explores combining geothermal, wind, and solar energy with other sustainable sources into air conditioning systems, emphasizing the potential benefits of reduced greenhouse gas emissions and enhanced energy resilience. For instance, employing solar, wind, and geothermal resources can reduce greenhouse gas emissions by over 75 % compared to conventional systems. It also explores techno-economic analysis, integration challenges, environmental impact, and sustainability assessment. The challenges, such as renewable energy intermittency, resulting in performance variations of about 10–15 %, necessitate the development of intelligent control algorithms and adaptive system architectures. Additionally, the potential research directions, technological innovations, and policy implications have also been discussed in detail.