Carbon monoxide and nitric oxide from biofuel fires in Kenya

Emission ratios (ER) of CO and NO relative to CO2 are reported from real ti me emission measurements on biofuel fires in Kenya. The experiments were bi ased on available fuels burning in local popular traditional and improved s toves. The mean dCO/6CO(2) ratios were 71, 79 and 74 mmol mol(-1) for firew ood, charcoal and agricultural residues, respectively, while the correspond ing mean dNO/dCO(2) ratios for these fuels, in the same order, were 1.8, 2 and 2.2 mmol mol(-1), respectively. Whereas stove design characteristics la rgely influenced the dCO/dCO(2) ratios, the fuel nitrogen content was the m ajor factor determining the dNO/dCO(2) ratios. The dCO/dCO(2) ratio for fue l derived NO is not affected by fire temperature but linearly depend on the fuel nitrogen content. Other important fuel parameters that influenced the observed emission ratio patterns include fuel moisture content, size and v olatile matter content in the case of charcoal. In comparison to savanna an d forest fires, biofuel fires tend to favour formation of reduced or partia lly oxidised compounds. It is clear that a change in energy preference up t he "energy ladder" leads to a reduction in the CO ER, an important result f or emission mitigation policy design. (C) 2001 Published by Elsevier Scienc e Ltd.