Fuel made from microalgae could potentially have a low carbon footprint and is an active area of research, although no large-scale production system has been commercialized to date. Microalgae are aquatic unicellular organisms. Although they, unlike most plants, have extremely simple cell structures, they are still photoautotrophic, able to use solar energy to convert carbon dioxide into carbohydrates and fats via photosynthesis. These compounds can serve as raw materials for biofuels like bioethanol or biodiesel. Therefore, even though combusting microalgae-based fuel for energy would still produce emissions like any other fuel, it could be close to carbon-neutral if they, as a whole, consumed as much carbon dioxide as is emitted during combustion.
The advantages of microalgae are their higher CO-fixation efficiency compared to most plants and their ability to thrive in a wide variety of aquatic habitats. Their main disadvantage is their high cost. It has been argued that their unique and highly variable chemical compositions may make it attractive for specific applications.
Microalgae also can be used as livestock feed due to their proteins. Even more, some species of microalgae produce valuable compounds such as pigments and pharmaceuticals.