Co-firing (or cofiring, also referred to as ''complementary firing'' or ''co-combustion'') is the

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion ...

of two different fuels in the same combustion system. Fuels can be solid fuels, liquid fuels or gaseous, and its source either

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

or renewable. Therefore, use of heavy fuel oil assisting coal power stations may technically be considered co-firing. The term co-firing was popularized in the 1980s and then referred specifically to the use of

waste Waste are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor Value (economics), economic value. A wast ...

solid residues (paper, plastic, solvents, tars, etc.) or

biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

in coal power stations that were designed only for the combustion of coal. Combustion Incineration

References

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