4.1.3. Emissions of CO

Figure 7 shows carbon monoxide emissions during air combustion of tested fuels. The instantaneous concentrations of CO for the combustion of biomass fuels were much lower than those for the combustion of reference coal. This can be attributed to the lower carbon content (Table 2) of biomass fuels. Release times of CO were 130–140 s for biomass and much longer, approximately 650 s, for coal. The highest CO emissions were detected during the combustion of char, both for biomass and coal. During air-combustion, the highest instantaneous concentration of CO were approximately 22 ppm and 19 ppm for coal and wheat straw, respectively.

**Figure 7.** Effect of fuel type on the instantaneous CO concentrations during air combustion.
