Cellulose is a natural organic compound consisting of long chains of several hundred to many thousands of linked glucose (a simple sugar) units. It is insoluble in water and most organic solvents, biodegradable and crystalline. This combination of characteristics gives it substantial mechanical strength.
Cellulose is the primary structural component of the cell walls in green plants and many species of algae, making it the most abundant organic polymer. It provides plants with their mechanical strength and is found in large amounts in cotton (about 90 percent), wood (40 to 50 percent), and hemp (about 57 percent).
Beyond its essential role in nature, cellulose also has a number of important industrial applications. It is the main ingredient in paper (90 to 99 percent cellulose), rayon (87 to 97 percent) and cellophane (92 to 98 percent) and is also used as a renewable biofuel.
Certain animals, such as ruminants (e.g., cattle, sheep and deer) and termites, digest cellulose with the aid of symbiotic microorganisms in their stomachs. Humans cannot digest it because they lack the enzyme cellulase, although it is their main form of dietary fiber and aids their digestion of other food materials. Cellulose is also added to foods as a fiber supplement, thickener, emulsifier, anti-caking agent, and dietary aid (because it absorbs water and adds bulk).
Cellulose is attractive as an alternative to petroleum-based plastics, which persist in the environment and contribute to microplastic pollution. This is because of its biodegradability and the fact that it is obtained from abundant and sustainable natural resources, such as wood and plant waste, and has good mechanical strength.
However, producing cellulose involves chemical-intensive processes using caustic soda and sulfuric acid, which can create environmental risks. Large scale production also requires substantial water and energy, contributing to greenhouse gas emissions, depending on the energy source. Large-scale forestry or agriculture for cellulose production can damage fragile habitats and reduce biodiversity. Moreover, some cellulose materials absorb water, reducing their durability and complicating their processing.
Researchers are actively working to improve cellulose as a substitute for plastics. One major goal is to make it stronger for uses such as packaging and other widely used items like cups and straws. Another is finding new sources of raw material, such as agricultural waste, recycled textiles, and even urban leaves, to reduce the need for large-scale tree farming.
Researchers are also investigating the use of bacteria to produce cellulose as a way of completely eliminating the land requirement. However, these innovations are still years away from becoming fully cost-effective and mass produced substitutes for plastics, likely at least five to ten years according to industry sources.