<P> Carbon dioxide can be used to extinguish flames by flooding the environment around the flame with the gas . It does not itself react to extinguish the flame, but starves the flame of oxygen by displacing it . Some fire extinguishers, especially those designed for electrical fires, contain liquid carbon dioxide under pressure . Carbon dioxide extinguishers work well on small flammable liquid and electrical fires, but not on ordinary combustible fires, because although it excludes oxygen, it does not cool the burning substances significantly and when the carbon dioxide disperses they are free to catch fire upon exposure to atmospheric oxygen . Their desirability in electrical fire stems from the fact that, unlike water or other chemical based methods, Carbon dioxide will not cause short circuits, leading to even more damage to equipment . Because it is a gas, it is also easy to dispense large amounts of the gas automatically in IT infrastructure rooms, where the fire itself might be hard to reach with more immediate methods because it is behind rack doors and inside of cases . Carbon dioxide has also been widely used as an extinguishing agent in fixed fire protection systems for local application of specific hazards and total flooding of a protected space . International Maritime Organization standards also recognize carbon dioxide systems for fire protection of ship holds and engine rooms . Carbon dioxide based fire protection systems have been linked to several deaths, because it can cause suffocation in sufficiently high concentrations . A review of CO systems identified 51 incidents between 1975 and the date of the report (2000), causing 72 deaths and 145 injuries . </P> <P> Liquid carbon dioxide is a good solvent for many lipophilic organic compounds and is used to remove caffeine from coffee . Carbon dioxide has attracted attention in the pharmaceutical and other chemical processing industries as a less toxic alternative to more traditional solvents such as organochlorides . It is used by some dry cleaners for this reason (see green chemistry). It is used in the preparation of some aerogels because of the properties of supercritical carbon dioxide . </P> <P> Plants require carbon dioxide to conduct photosynthesis . The atmospheres of greenhouses may (if of large size, must) be enriched with additional CO to sustain and increase the rate of plant growth . At very high concentrations (100 times atmospheric concentration, or greater), carbon dioxide can be toxic to animal life, so raising the concentration to 10,000 ppm (1%) or higher for several hours will eliminate pests such as whiteflies and spider mites in a greenhouse . </P> <P> It has been proposed that CO from power generation be bubbled into ponds to stimulate growth of algae that could then be converted into biodiesel fuel . </P>

Carbon dioxide gas is formed by the reaction of solid carbon and oxygen gas