A systematic literature review on the potential of marine microalgal biohydrogen and value-added products production: Pathways, strains, and future prospects

Abstract

Microalgal biohydrogen production from marine strains is a promising renewable energy source, leveraging high photosynthetic efficiency and CO₂ sequestration. In this review, a Systematic Literature Review (SLR) of 174 recent research articles (2023 – 2025) quantitatively and qualitatively evaluates marine microalgal biohydrogen production. The study reveals that among various pathways, dark fermentation with strains such as Chlorella vulgaris yields up to 190.9 mL H₂/g-VS (Volatile Solids) at pH 5.5 and 35 °C, closely paralleled by Nannochloropsis oceanica at 183.9 mL H₂/g-VS, while Chlorella saccharophila achieves 169.3 mL H₂/g-VS under similar conditions. Another fermentative pathway for biohydrogen production, photofermentation using Rhodobacter sp. produced 5.24 mL H₂/L/h at pH 7.0 and 25.6 °C. High-carbohydrate strains such as Tetraselmis suecica (31.72 – 32.06 %) and Isochrysis galbana (up to 32.05 %) exhibit superior fermentative potential, and process enhancements, such as Fe₃O₄/TiO₂ nanoparticle pretreatment, can increase hydrogen yields by up to 53 %. However, biophotolysis with Tetraselmis subcordiformis reaches 162 cm³ H₂/L, whereas microbial fuel cells achieve 9.8 mL H₂/L/day with Scenedesmus sp., showcasing the potential of different pathways in biohydrogen production. This review concludes that systematic pathway selection, hybrid intensification, and the exploitation of high-yield microalgal strains are essential for transitioning marine microalgal biohydrogen from promising research to practical, eco-friendly, and scalable energy solutions in the emerging green hydrogen economy.