# Biomass from Green Areas and Its Use for Energy Purposes
## 3 Results and Discussion
### Results of Calorimetric and Thermogravimetric Tests
The addition of sawdust to the biomass obtained from green areas reduced the nitrogen content (P2, P4, and P8) in comparison with solid fuels composed of 100% biomass of chestnuts, acorns, and fir cones (P1, P3, and P7). The exception was pine biomass pellets. The admixture of sawdust (P6) slightly increased the content of this element compared to this type of pellet without the addition of sawdust (P5). The percentage of total carbon content varied and depended on the composition of the pellets and the type of materials. The admixture of sawdust from coniferous trees did not importantly affect the carbon content in the analyzed solid fuels. Moreover, the percentage of hydrogen content in the analyzed solid fuels did not differ importantly. On the other \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Pellet Type** & \begin{tabular}{c} **Nitrogen** \\ **(\%)** \\ \end{tabular} & \
\begin{tabular}{c} **Carbon** \\ **(\%)** \\ \end{tabular} &
\begin{tabular}{c} **Hydrogen** \\ **(\%)** \\ \end{tabular} \\ \hline P1 & 0.991 \({}^{\text{a}}\)\(\pm\) 0.0311 & 46.3 \({}^{\text{a}}\)\(\pm\) 0.211 & 6.43 \({}^{\text{a}}\)\(\pm\) 0.311 \\ P2 & 0.882 \({}^{\text{a}}\)\(\pm\) 0.0111 & 45.2 \({}^{\text{a}}\)\(\pm\) 0.412 & 6.83 \({}^{\text{a}}\)\(\pm\) 0.921 \\ P3 & 1.060 \({}^{\text{a}}\)\(\pm\) 0.0421 & 50.6 \({}^{\text{a}}\)\(\pm\) 0.282 & 6.71 \({}^{\text{a}}\)\(\pm\) 0.111 \\ P4 & 0.961 \({}^{\text{a}}\)\(\pm\) 0.0512 & 50.6 \({}^{\text{a}}\)\(\pm\) 0.272 & 6.72 \({}^{\text{a}}\)\(\pm\) 0.821 \\ P5 & 1.150 \({}^{\text{a}}\)\(\pm\) 0.111 & 52.2 \({}^{\text{a}}\)\(\pm\) 0.614 & 6.24 \({}^{\text{a}}\)\(\pm\) 0.182 \\ P6 & 1.170 \({}^{\text{a}}\)\(\pm\) 0.131 & 51.7 \({}^{\text{a}}\)\(\pm\) 0.352 & 6.31 \({}^{\text{a}}\)\(\pm\) 0.132 \\ P7 & 1.200 \({}^{\text{b}}\)\(\pm\) 0.0521 & 49.5 \({}^{\text{a}}\)\(\pm\) 0.233 & 6.13 \({}^{\text{a}}\)\(\pm\) 0.212 \\ P8 & 0.991 \({}^{\text{a}}\)\(\pm\) 0.0621 & 48.2 \({}^{\text{a}}\)\(\pm\) 0.172 & 6.20 \({}^{\text{a}}\)\(\pm\) 0.181 \\ \hline \hline \end{tabular} Statistically significant differences marked by different letters (\(p\leq 0.05\)). The data were analyzed separately for each type of materials.  
\end{table} 
Table 6: The content of nitrogen, carbon, and hydrogen for the analyzed pellets produced from biomass. hand, the addition of coniferous sawdust caused an increase in the hydrogen content for the analyzed pellets (Table 6). Regarding the chemical composition of the biomass used for the production of pellets, it should be stated that it is diverse. In biomass from agriculture, which is intended for the production of solid fuels, the chemical composition is dominated by carbon [46]. The chemical composition of sunflower husk pellets is dominated by carbon and constitutes about 70%, nitrogen 9.1%, and hydrogen 8.8%. Sugar cane bagasse used for pellet production contains about 45% carbon, 12% hydrogen, and very low nitrogen content, below 0.5% [53; 54; 55]. The addition of coniferous sawdust to the material from which pellets are made reduces the nitrogen content in the final solid fuel by over 50%. In addition, there was no relationship between the addition of sawdust from coniferous trees and the content of carbon and hydrogen [33]. In turn, pellets made of Norway spruce contain 50.67% carbon, 7.16% hydrogen, and negligible amounts of nitrogen, at a level of 0.08%. In addition, pellets from deciduous biomass produced during the pruning of blackcurrants and raspberries contain, respectively: 55.13% and 52.30% carbon; 7.42% and 7.32% hydrogen, and 0.07% and 0.18% nitrogen [46]. Table 7 contains data on gas emissions during the combustion of solid fuels from biomass. Analyzing the research results, several significant relationships were observed. As a result of adding coniferous sawdust to the raw materials, a reduction in the amount of emitted gases was noted. For nitrogen oxides, the lowest emission was tested for solid fuels made of 50% pinecones and 50% coniferous sawdust (P6).