Biodiesel Production from Naturally Occurring Green Algae of the Al-Zawiya Coast, Libya

Abstract

Depleting fossil fuel resources, growing environmental concerns, and the global pursuit of sustainable development have driven the development of renewable energy alternatives, such as biodiesel from algae biomass. This study investigates biodiesel production from naturally occurring green algae collected from the Al-Zawiya coast, Libya, and evaluates its fuel properties according to ASTM standards. The algae were dried, ground, and Soxhlet-extracted with n-hexane to produce algae oil. The algae biomass yielded 7.96% oil. The oil was converted to biodiesel via alkaline transesterification using potassium hydroxide (KOH) as the catalyst. The process was carried out at 63°C with a methanol-to-oil molar ratio of 3:1, resulting in a biodiesel yield of approximately 90% (before washing). The produced biodiesel exhibited a kinematic viscosity of 5.24 mm²/s, a density of 888 kg/m³, a flash point of 110°C, a cloud point of -12.4°C, a pour point of -5.7°C, and an estimated cetane number of 49. The values for viscosity, flash point, and cetane number fell within the limits specified by the American Society for Testing and Materials (ASTM D6751) standard; however, this standard does not include specific requirements for density or low-temperature flow properties. The results indicate that green algal biomass is a promising feedstock for biodiesel production, although its oil content was found to be low. Furthermore, additional research covering engine performance, emissions, storage stability, production costs, and life cycle assessment is required before the potential for commercial application can be considered