The Fourth-Generation Biofuel: A Systematic Review on Nearly Two Decades of Research from 2008 to 2019

Fourth generation biofuel (FGB) uses genetically engineered crops to enhance the quality or quantity of the obtained algal biofuel. The reviews on FGB mostly concentrate on biogenetically modification techniques and tools applied for improving valuable components in microalgae. However, there are limited numbers of review papers that consider other aspects of FGB in biomass production stage including cultivation, harvesting, economy, consumption, and environment. This paper intends to conduct a goal-directed analysis of the bibliographic information on FGB. Preferred reporting item for systematic reviews and meta-analysis (PRISMA) is used for research methodology. To do so, the main keywords involved in FGB were selected by consulting two experts. The Scopus database was selected for literature search due to its outstanding capabilities in limiting the search to a specific field within manuscripts. Then, all included papers were classified into five groupings of strain selection, genetic modification, cultivation and harvesting, environment and sustainability, as well as industrialization and economy and each group was reviewed and discussed in the relevant section.