From sustainable feedstocks to renewable fuels: An interdisciplinary review of first- and second-generation pathways, engineering challenges, and the green energy transition

The global search for sustainable energy sources has put a greater emphasis on second generation synthetic bio-based energy. These advanced fuels offer a practical alternative to traditional fossil fuels, addressing key issues such as resource depletion, increased production costs, environmental damage and waste management inefficiencies. This review examines the current state of high-tech production technologies used in the production of synthetic materials, with a particular focus on the use of different raw materials such as algae, lignocellulosic biomass and municipal solid waste. Algal systems using photobioreactors have shown significant lipid outputs appropriate for biodiesel production, while lignocellulosic materials especially perennial grasses allow for the effective production of bioethanol and biobutanol. At the same time, converting MSW into biodiesel esters and biogas via transesterification and advanced gasification has become a promising approach. Although there have been these improvements, the industry still faces significant challenges such as high energy consumption, increased manufacturing expenses, extended processing durations, and inconsistent raw material supply chains. This research highlights the technological opportunities as well as the natural constraints of these methods, while promoting continued innovation in feedstock development, process enhancement, and system improvement. In the end, incorporating these technologies strategically may help move towards a circular economy and promote significant reduction of carbon emissions in industry and transportation.