Carbon dioxide (CO₂) is naturally abundant, relatively nontoxic, and nonflammable. It is one of the least expensive organic solvents currently available. Because of its green characteristics, that is, it is environmentally benign, carbon dioxide has been employed commercially as a solvent in food processing (for example, decaffeination of coffee and tea and extraction of hops), in reduced-emission coating systems, in production of polyurethane and polystyrene foams free of chlorofluorocarbons, and in extraction of organic contaminants from dredged material. These processes can involve high-capacity plants—over 50 × 10⁶ lb (22.5 × 10⁶ kg) per year in the case of decaffeination processes.