Recent Advances in Biofuel Production from Microalgae Biomass

Dear Colleagues,

The use of fossil fuels for energy production leads to increased pollution levels, including the amount of greenhouse gases emitted, and has global economic consequences. An alternative way to cover the increasing energy demand is to use renewable sources, including biomass. However, the production of bioenergy must be sustainable and environmentally friendly, not competing with food production, both in terms of land (low ILUC) and the components necessary for cultivation, i.e., water and nutrients. Conventional biomass use, the method of obtaining such feedstocks, and their availability raise concerns; therefore, a great deal of attention is focused on algal biomass. The distinguishing properties of microalgae are their growth rate, their potential for the fixation of carbon dioxide during photosynthesis, and their ability to accumulate valuable biocomponents. Microalgal biomass is a kind of green magazine where solar energy has been stored in the form of various chemical compounds. An appropriate conversion method makes it possible to produce heat, electricity, or liquid and gaseous biofuels, including bioethanol, biodiesel, green diesel, biomethane, biohydrogen, syngas, and bio-oil, from the biomass or components present in the microalgae cells. Microalgal biomass is not only a renewable energy substrate but also a biocatalyst for hydrogen production via biophotolysis and electrofermentation in microbial electrolysis cells. Biofuels from microalgae have the potential to promote energy diversification in the future and, due to the high level of carbon dioxide sequestration in biomass, to decarbonize transport. Biofuel production can be combined with bioremediation ('phycoremediation') processes favouring the microalgae-mediated removal of different environmental pollutants with lower cultivation costs. The commercialization of these technologies requires intensified research for efficient and low-cost biomass production conducted on a larger scale, optimization of environmental and technical cultivation conditions, efficient and low-cost harvesting, and refined conversion methods. There is a need for economic analyses of microalgal biofuel production to indicate the current level of competitiveness compared to other conventional energy carriers. Sustainable production of microalgal biomass, integrated energy conversion technologies in biorefineries, and appropriate regulations are key areas for the development of commercial microalgal biofuel production.

Prof. Małgorzata Hawrot-Paw
Guest Editor

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• microalgae
• microalgal biomass culture
• microalgal biomass conversion
• advanced biofuel
• bioethanol
• biodiesel
• syngas
• biohydrogen
• biomethane
• bioenergy
• biophotovoltaic (BPV)
• biorefinery
• biomass management
• energy efficiency
• microbial electrolysis cells (MECs)
• energy storage
• anaerobic digestion
• transport decarbonization
• biophotolysis

Title: Multi-biofuel production in the mixotrophic culture of Tetrasemis subscordiformis
Authors: Marcin Dębowski¹; Magda Dudek¹; Joanna Kazimierowicz²; Piera Quattrocelli³; Marcin Zieliński¹
Affiliation: 

1-Department of Environmental Engineering, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, 10-720 Olsztyn, Poland
2-Department of Water Supply and Sewage Systems, Faculty of Civil Engineering and Environmental Sciences, Bialystok University of Technology, 15-351 Bialystok, Poland
3-Sant’Anna School of Advanced Studies Crop Science Research Centre, Via Alamanni 22, San Giuliano Terme, 56010 Pisa, Italy

Abstract: Green algae of the species Tetraselmis subcordiformis are capable of producing many types of biofuels, including biohydrogen as a result of metabolic transformations, bio-oil that serves as a feedstock for biodiesel production, and biogas produced from microalgal biomass in the anaerobic digestion process. Previous research studies have only analysed the effectiveness of the individual processes. However, there is a lack of experimental work that combines, balances and complexes the possibility of producing these three types of biofuels in one technological line. The aim of the research carried out on a laboratory scale was to determine the possibilities and efficiency of the production of hydrogen, bio-oil and methane in a system of successive individual processes in the technology of cultivation and processing of Tetraselmis subcordiformis biomass. The growth of microalgae in the culture medium prepared on the basis of leachate after anaerobic digestion and the efficiency of biohydrogen production were evaluated, then the amount and composition of bio-oil accumulated in the cells was verified, and in the final phase, methane fermentation of Tetraselmis subcordiformis biomass after extraction was carried out.