<p>Industrialization and reciprocal population growth have spiked global energy demand and associated interest in sustainable and renewable energy sources. Concurrently, the global reliance on substantial use of petroleum-based fuels and products has raised serious environmental concerns, fuelling the search for eco-friendly alternatives. This review aims to explore the possibility of combining multiple waste materials to produce green energy, primarily focusing on potential utilization of animal fat wastes and waste shell-derived catalysts for biodiesel production. Biodiesel presents multi-dimensional benefits over fossil fuels, including but not limited to sustainability, high lubrication characteristics, non-toxicity, biodegradability, carbon neutrality, and environmental friendliness. Historically, researchers have faced challenges with its commercialization due to high upfront production costs, with 75% of these costs associated with expensive feedstocks and 12% with costly catalysts. This review emphasizes the cost-effectiveness and sustainability of using animal fat wastes, which are available in abundance and are more economical as compared to conventional feedstocks for biodiesel production. The calcium oxide catalysts, derived from waste shells, offer advantages in reusability, high stability, and ease of recovery. This review also discusses the life cycle assessment and economic analysis, aiming to provide a comprehensive understanding of how these waste materials can contribute to the&#xa0;sustainable and economically viable biodiesel industry. Despite existing research, this study identifies a gap in the literature concerning the large-scale application of animal fat wastes and waste shell-derived catalysts for biodiesel production.</p>