Valorization pathways of industrial waste from the wind energy sector: A systematic review

The wind energy industry plays a crucial role in renewable energy development. However, its growth also increases industrial waste from manufacturing processes. Among these, sludge and welding slag pose challenges due to their complex composition and limited reuse potential. Wind towers fabrication generates about 1000 t of paint sludge and 300 t of welding slag annually, underscoring the need for strategies to mitigate environmental impacts and enhance resource efficiency. Research on these by-products remains scarce, and no well-defined valorization routes have been established. This study presents a systematic review of existing valorization approaches for paint sludge and welding slag, with a specific but exploratory focus on their potential integration into asphalt mixtures for road construction. This perspective aligns with industrial symbiosis, where waste from one sector becomes a resource to another, advancing circular economy practices. Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a structured and multi-stage screening process was applied to identify relevant publications, resulting in a focused set of six studies suitable for detailed analysis. The results show that these residues have been valorized in applications such as primers, sealants, construction materials, thermal processes, and asphalt or concrete mixtures. Studies on cement-based formulations report that partial replacement of bitumen with paint sludge can reduces Global Warming Potential (GWP) by 39% while maintaining mechanical strength near 20 MPa, although no such evidence exists for asphalt mixtures. Recent years show a notable increase in publications, with China, India, and the United States leading research in this area. • Initial search retrieved >79,000 records; 432 were screened, 61 met relevance criteria, and 6 were included for detailed analysis (PRISMA). • Valorization of wind-energy waste remains underexplored ( n = 3 studies in this review). • Paint-sludge incorporation in cementitious materials can cut GWP by up to 39% while maintaining comparable mechanical performance. • Standardized test protocols and scale-up pathways are still needed for industrial deployment.