## 3 Results  
### Influence of Temperature and ER on Cold Gas Efficiency  
Figure 2a shows the effect of temperature on cold gas efficiency for the three ER levels studied. The results show values ranging from 22.7% (700 \({}^{\circ}\)C; ER 0.1) to 61.2% (850 \({}^{\circ}\)C; ER 0.3). The relatively low efficiency values may be because the light hydrocarbon content of the resulting gas was not considered for the LHV\({}_{\text{gas}}\) calculation. On the other hand, generally, for a specific ER, a temperature increase shows an increase in the efficiency of cold gas. However, for a 0.3 ER, the variations between the cold gas efficiency values were barely affected by the temperature, even showing a slight decrease when the temperature increased from 850 to 900 \({}^{\circ}\)C. If you analyze the three ER levels in more detail, you can see how the lowest efficiency values were found for a 0.1 ER.  
These trends are consistent with the results obtained in previous works reported by other authors and other materials, such as [PERSON] et al. (2017), who evaluated sludges at a fixed temperature of 780 \({}^{\circ}\)C and with an ER between 0.1 and 0.5 and achieved a simulated efficiency of between 30 and 35%. Also, [PERSON] et al. (2018) found that the efficiency of cold gas increased from 15 to 28% by increasing the temperature from 750 to 1050 \({}^{\circ}\)C for a mixture of biomass and coal. On the other hand, [PERSON] et al. (2019) found that when the ER increased to 0.28, the gas yield increased by approximately 20% for the gasification of urban solid waste.  
While higher temperatures in a gasification process require more energy input, cold gas efficiency was perhaps improved by enhancing reaction rates, reducing tar formation, and better converting it into valuable gases. At low temperatures, the gasification process is less efficient as it hinders the conversion of biomass into useful gases. This is because the chemical reactions involved in gasification are favored at higher temperatures. Therefore, at low temperatures, the biomass conversion is lower, and a low cold gas efficiency was obtained ([PERSON] et al., 2018). It is also important to indicate that electric heating was utilized to maintain the  
Figure 2: Effect of temperature (**a**) and ER (**b**) on cold gas efficiency.  
required operating temperatures for the gasifier. However, this input was not accounted for in the cold gas efficiency calculations. Consequently, while the cold gas efficiency generally improves with increasing temperature--reflecting enhanced gasification reactions--it does not capture the complete energy dynamics of the gasifier. This discrepancy indicates that the measured efficiency improvements may not fully align with the broader energy balance considerations.  
Figure 2b shows the effect of the equivalence ratio on cold gas efficiency for the four temperature levels analyzed. It is observed that the ER of 0.3 shows a higher cold gas efficiency for all the temperatures studied. However, the increase in temperature in the operating range studied hardly showed improvements in the efficiency of cold gas, ranging, for example, from 22.67% (750 \({}^{\circ}\)C) to 27.29% (900 \({}^{\circ}\)C) for the 0.1 ER; from 56.59% (750 \({}^{\circ}\)C) to 59.55% (900 \({}^{\circ}\)C) for the 0.3 ER; and from 46.16% (750 \({}^{\circ}\)C) to 53.38% (900 \({}^{\circ}\)C) for the 0.5 ER.  
Maintaining a high equivalence ratio during gasification has negative effects on cold gas efficiency. When there is an excessive amount of oxygen compared to the biomass, it can lead to over-oxidation of the fuel, resulting in a decrease in the overall energy conversion efficiency. Additionally, the high equivalence ratio can also lead to an increase in the formation of nitrogen compounds, which are harmful pollutants that contribute to air pollution and climate change [21]. Therefore, finding the right balance in the equivalence ratio is essential for maximizing cold gas efficiency and minimizing environmental impacts.