From Microalgae to Bioenergy: Recent Advances in Biochemical Conversion Processes

Abstract

Concerns about rising energy demand, fossil fuel depletion, and global warming have increased interest in developing and utilizing alternate renewable energy sources. Among the available renewable resources, microalgae biomass, a third-generation feedstock, is promising for energy production due to its rich biochemical composition, metabolic elasticity, and ability to produce numerous bioenergy products, including biomethane, biohydrogen, and bioethanol. However, the true potential of microalgae biomass in the future bioenergy economy is yet to be realized. This review provides a comprehensive overview of various biochemical conversion processes (anaerobic digestion, direct biophotolysis, indirect biophotolysis, photo fermentation, dark fermentation, microalgae-catalyzed photo fermentation, microalgae-catalyzed dark fermentation, and traditional alcoholic fermentation by ethanologenic microorganisms) that could be adapted to transform microalgae biomass into different bioenergy products. Recent advances in biochemical conversion processes are compiled and critically analyzed, and their limitations in terms of process viability, efficacy, scalability, and economic and environmental sustainability are highlighted. Based on the current research stage and technological development, biomethane production from anaerobic digestion and bioethanol production from traditional fermentation are identified as promising methods for the future commercialization of microalgae-based bioenergy. However, significant challenges to these technologies’ commercialization remain, including the high microalgae production costs and low energy recovery efficiency. Future research should focus on reducing microalgae production costs, developing an integrated biorefinery approach, and effectively utilizing artificial intelligence tools for process optimization and scale-up to solve the current challenges and accelerate the development of microalgae-based bioenergy.

Biohydrogen Production under Aerial Conditions by a Nitrogen-Fixing Bacterium Isolated from a Steel Signboard

“…Ar is commonly used as a replacement gas in biohydrogen production studies because it is inert and does not react with the bacteria. In an Ar atmosphere, nitrogenases remain inactive because of the lack of a substrate, and biohydrogen is produced by hydrogenases [34]. In an Ar atmosphere, BRCNF001, BRCNF007, and R. sphaeroides had significantly lower cell weights under aerial-phase conditions than under liquid-phase ones, the cell weights of BRCNF002 and BRCNF008 were not significantly different, and the cell weights of BRCNF003, BRCNF004, and BRCNF006 were larger under aerial-phase conditions than under liquid-phase ones (Figure 3a).…”

An Updated Review of Recent Applications and Perspectives of Hydrogen Production from Biomass by Fermentation: A Comprehensive Analysis

“…The improvement of fermenting microorganisms [81][82][83] to increase the production potential is a future field of research. To improve hydrogen production, future research may converge on the identification of adapted microorganisms, allowing a more comprehensive substrate exploration [84][85][86], in particular, the search for more sustainable solutions for an immense variety of wastes from industrial production processes.…”

Effects of Trophic Modes on the Lipid Accumulation of Parachlorella kessleri TY

“…As worldwide energy demand continues to increase, biodiesel, a source of clean energy, is presently receiving extensive research attention. For this reason, microalgae are considered to be extremely valuable due to their numerous advantages, such as their small size, the possibility of cultivation without the need for arable land, and their high photosynthetic efficiency and biomass productivity, especially in terms of their storage of rich lipids [1,2]. Therefore, they are currently considered to be a potential source of biodiesel.…”