# Biomass from Green Areas and Its Use for Energy Purposes
## 3 Results and Discussion
### Results of Calorimetric and Thermogravimetric Tests
On the other hand, the highest pollution of nitrogen oxides was recorded for solid fuels made out of fir cones-- 119.14 mg\(\cdot\)m\({}^{3}\) (P7). Pellets made of chestnuts and acorns have sulfur dioxide emissions below 2.0 mg\(\cdot\)m\({}^{3}\). Pellets from fir cones were characterized by the highest emission of sulfur dioxide--4.12 mg\(\cdot\)m\({}^{3}\) (P7). In the case of carbon dioxide, pellets made of acorns and coniferous sawdust (P4) were characterized by the lowest emission of this gas. When burning the remaining pellets, the carbon dioxide emission was above 1%. Carbon monoxide emission for pellets P1-P4 was below 100 mg\(\cdot\)m\({}^{3}\). In turn, as a result of the combustion of pellets P5-P8, the emission of this gas exceeded 100 mg\(\cdot\)m\({}^{3}\). Taking into account the emission of sulfur dioxide and nitrogen oxides, pellets made of fir cones (P7) had the highest emission among the tested solid fuels (Table 7). The emission of gases depends primarily on the composition of the wood pellets subjected to the combustion process. When burning waste biomass, we recorded various amounts of emitted gases. During the combustion of corn cobs, the emissions to the atmosphere were about 300 mg\(\cdot\)m\({}^{3}\) of carbon monoxide and 50 mg\(\cdot\)m\({}^{3}\) of nitrogen oxides [56]. As a result of burning coniferous wood, we note lower nitrogen oxide emissions compared to hardwood. This fact is confirmed by the results of emissions into the atmosphere of 30% \begin{table}
\begin{tabular}{c c c c c} \hline
**Pellet Type** & \begin{tabular}{c} **CO** \\ **(mg\(\cdot\)m\({}^{3}\))** \\ \end{tabular} & \begin{tabular}{c} **CO\({}_{2}\)** \\ **(\%)** \\ \end{tabular} & \
\begin{tabular}{c} **SO\({}_{2}\)** \\ **(mg\(\cdot\)m\({}^{3}\))** \\ \end{tabular} &
\begin{tabular}{c} **NO\({}_{x}\)** \\ **(mg\(\cdot\)m\({}^{3}\))** \\ \end{tabular} \\ \hline P1 & 92.2 \({}^{\text{b}}\)\(\pm\) 4.47 & 1.150 \({}^{\text{a}}\)\(\pm\)0.06 & 1.44 \({}^{\text{b}}\)\(\pm\)0.0721 & 97.3 \({}^{\text{a}}\)\(\pm\) 4.87 \\ P2 & 82.7 \({}^{\text{a}}\)\(\pm\) 3.96 & 1.010 \({}^{\text{a}}\)\(\pm\)0.05 & 1.29 \({}^{\text{a}}\)\(\pm\)0.0711 & 91.2 \({}^{\text{a}}\)\(\pm\) 4.56 \\ P3 & 89.4 \({}^{\text{b}}\)\(\pm\) 4.61 & 1.020 \({}^{\text{a}}\)\(\pm\)0.05 & 1.11 \({}^{\text{a}}\)\(\pm\)0.0623 & 96.9 \({}^{\text{b}}\)\(\pm\) 4.84 \\ P4 & 79.2 \({}^{\text{a}}\)\(\pm\) 4.13 & 0.981 \({}^{\text{a}}\)\(\pm\)0.05 & 1.01 \({}^{\text{a}}\)\(\pm\)0.0632 & 88.9 \({}^{\text{a}}\)\(\pm\) 4.45 \\ P5 & 110.0 \({}^{\text{a}}\)\(\pm\) 5.51 & 1.330 \({}^{\text{a}}\)\(\pm\)0.07 & 2.68 \({}^{\text{a}}\)\(\pm\)0.131 & 81.1 \({}^{\text{b}}\)\(\pm\) 4.06 \\ P6 & 102.0 \({}^{\text{a}}\)\(\pm\) 5.07 & 1.250 \({}^{\text{a}}\)\(\pm\)0.06 & 2.11 \({}^{\text{a}}\)\(\pm\)0.111 & 65.3 \({}^{\text{a}}\)\(\pm\) 3.27 \\ P7 & 127.0 \({}^{\text{b}}\)\(\pm\) 6.34 & 1.170 \({}^{\text{a}}\)\(\pm\)0.06 & 4.12 \({}^{\text{b}}\)\(\pm\)0.0912 & 119.0 \({}^{\text{b}}\)\(\pm\) 5.61 \\ P8 & 114.0 \({}^{\text{a}}\)\(\pm\) 5.71 & 1.010 \({}^{\text{a}}\)\(\pm\)0.05 & 3.24 \({}^{\text{a}}\)\(\pm\)0.121 & 106.0 \({}^{\text{a}}\)\(\pm\) 5.82 \\ \hline \end{tabular} Statistically significant differences marked by different letters (\(p\leq\) 0.05). The data were analyzed separately for each type of material.  
\end{table} 
Table 7: Average values of gaseous pollutants generated during pellet combustion. less nitrogen oxides during the combustion of coniferous pellets compared to hardwood pellets [57]. Numerous scientific reports indicate that the formation of nitrogen oxides is determined by the type of solid, liquid, or gaseous fuel combusted in various types of boilers [58; 59]. NO\({}_{\mathrm{x}}\) emissions depend largely on the amount of nitrogen in the fuel [60], and this is important when combusting nitrogen-rich solid, liquid, or gas fuels [61]. Pollutants such as NO\({}_{\mathrm{x}}\) and particulate matter are the result of nitrogen, potassium, chlorine, calcium, sodium, magnesium, phosphorus, and sulfur in the fuel [62].