Biodiesel production from freshwater microalgae of Ghana

Abstract

Abstract. Ruth OA, Ameka GK, Annag T. 2020. Biodiesel production from freshwater microalgae of Ghana. Bioteknologi 17: 37-45. Due to rising oil prices and concerns about global warming, biodiesel has gained prominence as an alternative energy source. Biodiesel produced from microalgae is a potential carbon–neutral and renewable alternative to petroleum fuels. This study aimed to investigate the viability of manufacturing biodiesel from microalgae harvested from freshwater bodies in Ghana as an environmentally sustainable alternative to fossil diesel. In the study, water samples with algal blooms were taken from the Weija reservoir, wastewater ponds in and around the main campus of the University of Ghana in Prampram, and a freshwater pond in Accra's Teshie neighborhood. Four (4) microalgae were isolated and identified based on their morphology and cultivation ease: Oedogonium sp., Chroococcus sp., Spirogyra sp., and Closterium sp. After being grown in a 2-liter reagent bottle Photobioreactor (improvised) utilizing sunlight as the energy source, these isolates were collected, filtered to remove excess water, and centrifuged to form pastes. Extracting the oil from the algae required drying and grinding the pastes into powder. And then, the oils were transesterified into biodiesel. In terms of percentage dry weight, Oedogonium sp. exhibited a considerable increase (55.8%) and Closterium sp. exhibited a decrease (40.1%), while Chroococcus sp. and Spirogyra sp. ranged between 50.2 and 50.0%, respectively. Significant volumes (20- 38%) of microalgal oil were successfully extracted with hexane and diethyl ether and converted into biodiesel. Results also suggested that these species may grow abundantly under ambient temperature, air, natural source of light, and suitable substrate. 94% of biodiesel was produced from Closterium sp., compared to 80% from Chroococcus sp. The highest biodiesel yield was 49% for Oedogonium sp., and the lowest was 33% for Spirogyra sp. This study isolated and identified four freshwater microalgae that are seldom employed in biodiesel manufacturing studies. Conclusion: Oedogonium sp., Closterium sp., Spirogyra sp., and Chroococcus sp. are viable species capable of producing a large amount of algal oil for biodiesel synthesis. Consequently, efforts must be made to create a more effective and economically viable technology for the large-scale growth of algae for biodiesel production in Ghana. In addition, a comprehensive economic study must be conducted on every component of the algae-to-biodiesel production process. It can minimize the cost of biodiesel production, hence making it a more economical alternative to fossil fuel in Ghana.