As of 2024, approximately 81.5% of global energy consumption is still derived from non-renewable fossil fuels, such as coal, oil, and natural gas. This highlights the urgent need to transition to alternative energy sources amid the escalating climate crisis. Cyanobacteria and microalgae have emerged as promising biocatalysts in microbial fuel cells (MFCs) for eco-friendly energy production, owing to their photosynthetic abilities and resilience in regard to various environmental conditions. This review explores the potential of cyanobacteria and microalgae to drive bioelectricity generation via metabolic and extracellular electron transfer processes, leveraging their ability to fix carbon and nitrogen, while thriving in challenging environments. Bioengineering and electrode design advances are integrated to enhance the electron transfer efficacy and constancy of cyanobacteria-based MFCs. This approach addresses the growing demand for carbon-neutral energy and can be applied to wastewater treatment and bioremediation scenarios. By synergizing biological innovation with sustainable engineering techniques, this review establishes cyanobacteria and microalgal-driven MFCs as a scalable and eco-friendly platform for next-generation energy systems. The findings lay the groundwork for further exploration of the role of cyanobacteria and microalgae in bridging the gap between renewable energy production and environmental stewardship.

This study assesses the aptitude of heterocystous cyanobacterial strain Dolichospermum spiroides MBDU 903 in integrated wastewater treatment and biofuel production at a laboratory scale. The efficiency of the strain was assessed based on pigment accumulation, growth kinetics, nutrient remediation efficiency, and biodiesel fuel quality. The results demonstrated that the biomass productivity of D. spiroides MBDU 903 ranged from 69.27 to 167.08 mg L⁻¹ day⁻¹ across various nutrient regimes, achieving a maximum lipid content of 31% (w/w). Cultivation in municipal wastewater with BG11+ (50% v/v) yielded the highest pigment production biomass. The physicochemical properties of the derived biodiesel were estimated from gas chromatography-derived fatty acid methyl ester (FAME) profiles. Furthermore, the biorefinery potential was explored as a proof-of-concept by fermenting the post-transesterification residual biomass with Saccharomyces cerevisiae, yielding 14.5 mg/g of bioethanol from the pretreated residue. While a 10 L pilot-scale trial was conducted, significant productivity drops suggest that further optimization is required to bridge the gap between laboratory results and practical application. This study provides a baseline evaluation of the dual-fuel potential of a heterocystous cyanobacterium under wastewater-integrated conditions.