Efficiency and biotechnological aspects of biogas production from microalgal substrates.

•Conversion of photosynthetic microalgae into biogas is a simple and straight-forward route for bioenergy generation.•This review provides a state-of-the-are summary of the research made in the field of anaerobic digestion processes of microalgal biomass.•Biological and technological aspects are summarized.•Future prospects and challenges are highlighted.•An extended data summary is provided as Tables 1–3, allowing a comprehensive overview of the past achievements.