The rapid growth of the wind energy industry has resulted in a significant increase in Wind Turbine Blade (WTB) waste, posing challenges for recycling due to the composite materials used in their construction. Several proposed techniques, including mechanical, thermal, and chemical processes, have been considered for wind-blade recycling, but determining the most effective approach remains a critical issue. This study presents the first comprehensive systematic review of available wind-blade recycling processes, evaluating their economic, technical, and environmental performance. Additionally, we consider the physical and mechanical properties of the recycled materials, which can aid in identifying potential markets for these materials. Among the various recycling technologies, microwave pyrolysis emerges as the most promising technique for recycling large quantities of WTB, despite some challenges and uncertainties surrounding its effectiveness and feasibility at an industrial scale. However, the optimal recycling technique for WTB will depend on multiple factors, including the blade material, the desired environmental impact, and the economic feasibility of the process. Based on this review, mechanical recycling appears to be more energy-efficient, while the fluidised bed recycling process demonstrates a lower primary energy demand, global warming potential, and power consumption. These findings provide valuable guidance for decision-makers in the wind energy industry to develop effective waste management strategies and plans for sustainable wind energy development. Addressing WTB waste and implementing efficient recycling techniques will be critical in mitigating environmental impacts and promoting sustainability in the renewable energy sector as the wind energy industry grows.

The ongoing pursuit of enhanced efficiency and sustainability in power transformer cooling systems has spurred extensive research into the properties and performance of insulating fluids. This review explores the evolution of transformer cooling technologies, focusing on traditional mineral oils and the emerging roles of alternative fluids, such as natural and synthetic esters, and nanofluids. Mineral oils, though widely used, degrade over time, leading to a reduction in breakdown voltage (BDV) from 46 kV to 30 kV, exhibiting low fire resistance. Natural and synthetic esters provide improved biodegradability, fire safety but have higher viscosities—potentially limiting convective cooling. Nanofluids, have demonstrated BDV enhancements of up to 47.8%, reaching 88.7 kV in optimised formulations, alongside increases in partial discharge inception voltage (PDIV) of 20–23%. Additionally, thermal conductivity improvements of 5–20% contribute to enhanced heat dissipation. Moreover, it addresses challenges such as nanoparticle agglomeration, sedimentation, ageing, and compatibility with transformer materials. The analysis provides critical insights into the trade-offs between technical performance and economic feasibility. Concluding with an outlook on future research directions, the review identifies key parameters across various categories, establishing a roadmap for nanofluid integration with existing transformer systems.