Cofiring

Cofiring is the combustion of two different types of materials at the same time. One of the advantages of cofiring is that an existing plant can be used to burn a new fuel, which may be cheaper or more environmentally friendly. For example, biomass is sometimes cofired in existing coal plants instead of new biomass plants. Cofiring can also be used to improve the combustion of fuels with low energy content. For example, landfill gas contains a large amount of carbon dioxide, which is non-combustible. If the landfill gas is burned without removing the carbon dioxide, the equipment may not perform properly or emissions of pollutants may increase. Cofiring it with natural gas increases the heat content of the fuel and improves combustion and equipment performance. As long as the electricity or heat produced with the biomass and landfill gas was otherwise going to be produced with non-renewable fuels, the benefits are essentially equivalent whether they are cofired or combusted alone. Also, cofiring can be used to lower the emission of some pollutants. For example, cofiring biomass with coal results in less sulfur emissions than burning coal by itself.