Algae are a large and diverse group of single-cellular or multi-cellular, photosynthetic or/and non-photosynthetic organisms which can inhabit freshwater and seawater as well. They are able to convert sunlight and carbon-dioxide into their biomass and producing oxygen (photosynthesis).
Under the right conditions (light, temperature, pH etc.) algal growth occur at an exponential rate producing hundred fold of algal cells according to the inoculated cells. The produced algal biomass contains three main components: proteins, carbohydrates, and natural oil. These attributions (exponential growth rate, producing natural oil, convert carbon-dioxide into biomass etc.) make algae a potential natural key to answer such kind of environmental questions like global warming, decreasing fossil fuels, and energy crisis.