## 1 Introduction
### Life Cycle Assessment (LCA)  
LCA data indicate that the production phase of carbon fibers (CFs) and carbon fiber-reinforced polymers (CFRPs) generates significantly higher environmental impacts than steel manufacturing [18]. Greenhouse gas (GHG) emissions associated with CF production range from 11.46 to 154.40 kg CO\({}_{2}\)-eq per kg [18], with commonly cited values between 22.4 and 31 kg CO\({}_{2}\)-eq/kg [19]. For instance, conventional carbon fiber (C-CF) results in emissions of 24.83 kg CO\({}_{2}\)-eq/kg, while energy-saving variants (ES-CF) can lower this to 19.29 kg CO\({}_{2}\)-eq/kg, assuming an annual production scale of 3000 tons [20]. Energy consumption in CF production typically ranges between 100 and 900 MJ/kg, but can reach up to 1150.5 MJ/kg, or even 4436.3 MJ/kg for the polyacrylonitrile (PAN) precursor [18]. In comparison, steel production leads to considerably lower GHG emissions, estimated at 1.7-2.1 kg CO\({}_{2}\)-eq/kg, and energy demand in the range of 20-30 MJ/kg [18; 20; 21]. Despite these higher environmental inputs during production, CFRP materials can deliver substantial sustainability benefits over the entire lifecycle of the final product [18]. Their high strength-to-weight ratio, durability, and resistance to corrosion can significantly reduce material demand and extend service life. In structural applications, such as bridges, replacing steel with CFRP tendons may result in 18-28% lower GHG emissions during the production phase due to reductions in concrete and reinforcement volumes. Similarly, in wind turbine blades, CF allows for energy payback times (EPBTs) of just 0.49-0.73 months, and carbon payback times (CPBTs) of 0.22-0.37 months, meaning the environmental cost of CF production is offset in under a month of operation [18; 21]. Moreover, advancements in production processes, such as the implementation of waste heat recovery systems, have the potential to enhance energy efficiency by up to 86% in specific stages of carbon fiber manufacturing, particularly during the stabilization phase. A critical element in the development of such materials is the systematic use of Life Cycle Assessment (LCA), which offers a reliable framework for evaluating their environmental performance and identifying key stages for process optimization. Modern processing technologies enable precise control over material microstructure and geometry, which creates opportunities for using polymer-based fiber composites in demanding industrial sectors such as urban infrastructure or mining operations, especially in applications that benefit from novel functionalities, including luminescence. The environmental performance of CFRP-based systems must also be considered within the broader regulatory context of the European Union. For instance, the Directive (EU) 2019/904 [22] on the reduction in the impact of certain plastic products on the environment, commonly referred to as the Single-Use Plastics (SUP) Directive, along with the upcoming Packaging and Packaging Waste Regulation (PPWR), promotes a transition toward circular and resource-efficient material systems. Key targets include achieving 30% recycled content in plastic beverage bottles by 2030 and reaching 90% separate collection of plastic containers by 2029. While these policies focus primarily on consumer plastic packaging, they reflect a broader legislative shift emphasizing material recovery, emissions reduction, and lifecycle optimization. Although CFRP composites are associated with relatively high environmental impacts at the production stage, their long-term application contributes to the reduction in operational emissions and extension of service life, making them consistent with the strategic objectives of EU climate and sustainability policies. Innovative design strategies that prioritize material efficiency, durability, and circularity can help align industrial practices with regulatory expectations, while reducing waste and advancing climate neutrality goals set out in the European Green Deal.