Fuente: Asqueous Extraction Byproducts Concerns about the depletion of petroleum supplies, energy security, air pollution, and global warming have fueled global interest in finding sustainable or renewable alternative energy sources. Many countries believe that biofuels will soon be essential for self-sufficient energy generation as well as reducing emissions of air pollutants and greenhouse gases such carbon dioxide, nitrogen oxide, sulfur oxides, and methane. Biofuels are an eco-friendly and sustainable renewable energy source that are created from biomass such as agricultural produce or organic waste materials. Microalgae often degrade or ferment vegetable and animal organic materials to generate liquid or gas fuels such as methane, ethanol, and hydrogen through thermal and chemical processes. Biofuels include bioethanol, biodiesel, biomethane, and biobutanol. First-generation biofuels employed sugars found in edible crops, but second-generation biofuels may use lignin, albeit it is extremely refractory, and cellulose from sources such as wood pulp. The conversion of non-biodegradable organic molecules to fermentable sugars necessitates extra technological procedures such as thermal, chemical, and enzymatic treatments, raising the cost. Microalgae play a vital role in the natural carbon cycle, and they may efficiently use carbon resources in water and soil. The ability of microalgae to reduce CO2 emissions and generate oil with high productivity has been demonstrated. Renewable biofuels are required to replace petroleum-derived transportation fuels, which contribute to global warming and are limited in availability. Biodiesel and bioethanol are two possible renewable fuels that have received the greatest attention. As illustrated here, biodiesel and bioethanol produced from agricultural crops using current technologies cannot replace fossil-based transportation fuels indefinitely, but there is a solution. Biodiesel from microalgae appears to be the only renewable biofuel capable of totally replacing petroleum-derived transportation fuels without jeopardizing food and agriculture supplies. Most prolific oil crops, such as oil palm, fall well short of microalgae in terms of producing the requisite volumes of biodiesel on a sustainable basis (Brennan and Owende in Renewable and sustainable energy reviews 14:557–577, 2010 [3]; Chisti in Biotechnology advances 25:294–306, 2007 [8]; Mata et al. in Renewable and sustainable energy reviews 14:217–232, 2010 [30]). Algae-based biofuels have recently been created and categorized as third-generation biofuels. Because microalgae have no lignin, they may be easily converted to monosaccharides for ethanol generation. Furthermore, microalgae grow quickly, produce biofuel efficiently, and have a short harvesting cycle, resulting in cheaper costs than other feedstocks. Algal oil and biomass are easily turned to diesel and gasoline. Microalgae may be grown anywhere, including wastelands, coasts, and oceans, as long as photosynthesis is feasible. Furthermore, they don’t compete with culinary crops for cultivation area or space.