<p>This study evaluated the ecological impacts of three generations of biorefineries using an integrated circularity-life cycle assessment (LCA) approach. In this context, LCA of three distinct biorefinery scenarios was conducted utilising the Greenhouse Gases, Regulated Emissions, and Energy use in Transportation (GREET^®) model to compare their environmental impacts. Two third-generation scenarios, i.e., algae hydrothermal liquefaction (HTL)—pathway I and combined algae processing (CAP)—pathway II, and one second-generation scenario, i.e., palm fatty acid distillation (PFAD)—pathway III, were considered by following a well-to-wheel system framework. Pathway I and II exhibited very low emissions with negative net emissions in pathway I. On the contrary, pathway III had the highest emissions. Based on the results obtained from this study, exploitation of marine biomass (in the third-generation) might offer a sustainable solution to global energy demands with emerging green technologies, such as hydrothermal treatment, advanced fermentation, and green solvents that are essential for improving marine biorefineries. Policies must be formulated by setting standards prioritising renewable energy, resource efficiency, and waste reduction that are important in shaping the sustainability and efficiency of biorefineries across the globe.</p>