Concentrated animal feeding operations such as dairies produce a large amount of manure, termed as dairy biomass (DB), which could serve as renewable feedstock for thermal gasification. DB is a low-quality fuel compared to fossil fuels, and hence the product gases have lower heat content; however, the quality of gases can be improved by blending with coals. This paper deals with air-steam fixed-bed counterflow gasification of dairy biomass-Wyoming coal blend (DBWC). The effects of equivalence ratio (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1.6</mml:mn><mml:mo><</mml:mo><mml:mi>Φ</mml:mi><mml:mo><</mml:mo><mml:mn>6.4</mml:mn></mml:mrow></mml:math>) and steam-to-fuel ratio (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.4</mml:mn><mml:mo><</mml:mo><mml:mi>S</mml:mi><mml:mo>:</mml:mo><mml:mi>F</mml:mi><mml:mo><</mml:mo><mml:mn>0.8</mml:mn></mml:mrow></mml:math>) on peak temperatures, gas composition, gross heating value of the products, and energy recovery are presented. According to experimental results, increasing Φ and (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>S</mml:mi><mml:mo>:</mml:mo><mml:mi>F</mml:mi></mml:math>) ratios decreases the peak temperature and increases the H 2 and CO 2 production, while CO production decreases. On the other hand, the concentrations of CH 4 and C 2 H 6 were lower compared to those of other gases and almost not affected by Φ.
