Methane, the main constituent of natural gas can be produced from algae in various methods, namely gasification, pyrolysis and anaerobic digestion. In gasification and pyrolysis methods methane is extracted under high temperature and pressure. Anaerobic digestion is a straightforward method involved in decomposition of algae into simple components then transforming it into fatty acids using microbes like acidogenic bacteria followed by removing any solid particles and finally adding methanogenic archaea to release a gas mixture containing methane. A number of studies have successfully shown that biomass from microalgae can be converted into biogas via anaerobic digestion. Therefore, in order to improve the overall energy balance of microalgae cultivation operations, it has been proposed to recover the energy contained in waste biomass via anaerobic digestion to methane for generating electricity.