1. Introduction.- 2. Genetically Modified Microalgae for Biofuel Production Strain Selection Cultivation and Harvesting of Genetically Modified Microalgae.- 3. Residue from Biofuel Extraction.- 4. Health and Environmental Concerns of Fourth Generation Biofuels.- 5. Regulations on Cultivation and Processing of the Genetically Modified Algae.- 6. Carbon dioxide sequestration.- 7. Water Footprint.- 8. Current Status and Key Challenges