Polymer Nanocomposites (PNC) are the first choice materials that contribute majorly to the field of Renewable energy. The three primary applications (Solar energy, Wind Turbines, Fuel and Hydrogen cells), where PNCs are employed, ideally benefit from the High Mechanical Strength, Thermal Stability, and Conductivity properties of PNCs. Moreover, these specific properties not only make PNCs the first choice but also reduce the possibility of their recycling or easy degradation. The recyclability as well as the sustainability of PNC are some of the issues that result from the Complex composition and thermo-chemical stability, which subsequently become potential hazards to the environment. This article is about the importance of Polymer Nanocomposites (PNC) in Renewable energy and their associated issues and possible solutions of PNCs’ Recyclability, Sustainability, and Waste Management. Moreover, this paper introduces in detail the different methods for recycling, including Mechanical Recycling, Chemical Recycling, Closed-loop Recycling, and the biodegradable approach. It also discusses Advanced material Science like self-healing PNCs, Recovery Techniques of Nanofillers, and Bio-based nanocomposites. This paper also offers all this information, along with a thorough study of the Economic and Environmental Impact of Nanocomposites plus their future trends and research directions.