Cellulose is the most abundant organic compound on the earth. It is found in every plant on the earth, making up the structure of a plant's cell walls and helping to hold the plant together.
Since cellulose is a strong material and works for the sole purpose of holding fibers together, it is difficult to break down, so much so that it cannot be digested by humans. It is categorized as a dietary fiber in human diets. Other organisms, such as herbivorous farm animals and termites, are able to digest it, however. Microorganisms and protozoans are also able to break down cellulose.
Cellulose is a complex carbohydrate or polysaccharide of glucose units, or sugars, that help hold the fibers together. It is commonly found in plant matter, wood and cotton. Cellulose is often used as an emulsifier, a thickening agent, and is also useful for making paper, plastic and rayon. Its firm structure makes it ideal for holding, storing and distributing energy as well.
Since it is a great source of energy, it is possible that cellulose could become the main source of fuel in the United States and around the world. In order for this to happen, as of 2011, scientists have been working to develop an easier system for separating the cellulose from the plant.