Reduction reverts completely combusted hydrocarbons into a form that can be used as fuel. Note that reduction is the opposite of combustion - it is the endothermic removal of oxygen from hydrocarbons. Typically combustion and reduction exist in equilibrium in any burning process. Reduction in a gasifier occurs when carbon dioxide and water vapor flows through heated charcoal (primarily carbon). The heated carbon removes the oxygen from both the carbon dioxide and the water vapor. The oxygen is spread to the carbon atoms, forming covalent bonds in the form of carbon monoxide. Oxygen has a higher affinity for carbon than either hydrogen or itself. This leaves the remaining hydrogen atoms to form their natural diatomic. Therefore, two reactions occur from the addition of carbon and heat: carbon dioxide is reduced to carbon monoxide and water vapor is reduced to diatomic hydrogen and carbon monoxide (www.gekgasifier.com). The FAO study found that the rate of reduction is only high enough to run a gasifier at temperatures above about 973 K (17). A summary of the reduction reaction is shown below in Figure 2.