# Biomass from Green Areas and Its Use for Energy Purposes
## 3 Results and Discussion
### Results of Calorimetric and Thermogravimetric Tests
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Pellet Type** & \begin{tabular}{c} **Ash Content** \\ **(\%)** \\ \end{tabular} & \
\begin{tabular}{c} **Volatile Compounds** \\ **(\%)** \\ \end{tabular} &
\begin{tabular}{c} **Calorific Value** \\ **(MJ\(\cdot\)kg\({}^{-1}\))** \\ \end{tabular} \\ \hline P1 & 1.88 \({}^{\text{a}}\)\(\pm\) 0.0911 & 78.9 \({}^{\text{a}}\)\(\pm\) 0.611 & 17.5 \({}^{\text{b}}\)\(\pm\) 0.111 \\ P2 & 1.62 \({}^{\text{a}}\)\(\pm\) 0.0422 & 80.2 \({}^{\text{b}}\)\(\pm\) 0.101 & 16.9 \({}^{\text{a}}\)\(\pm\) 0.0422 \\ P3 & 1.81 \({}^{\text{a}}\)\(\pm\) 0.102 & 79.3 \({}^{\text{a}}\)\(\pm\) 0.122 & 19.5 \({}^{\text{a}}\)\(\pm\) 0.0512 \\ P4 & 1.76 \({}^{\text{a}}\)\(\pm\) 0.0623 & 79.9 \({}^{\text{a}}\)\(\pm\) 0.121 & 19.1 \({}^{\text{a}}\)\(\pm\) 0.112 \\ P5 & 1.40 \({}^{\text{a}}\)\(\pm\) 0.211 & 76.8 \({}^{\text{a}}\)\(\pm\) 0.0911 & 19.3 \({}^{\text{b}}\)\(\pm\) 0.162 \\ P6 & 2.02 \({}^{\text{b}}\)\(\pm\) 0.131 & 77.9 \({}^{\text{b}}\)\(\pm\) 0.0192 & 18.9 \({}^{\text{a}}\)\(\pm\) 0.0635 \\ P7 & 1.27 \({}^{\text{a}}\)\(\pm\) 0.0821 & 74.7 \({}^{\text{a}}\)\(\pm\) 0.0712 & 18.6 \({}^{\text{a}}\)\(\pm\) 0.0554 \\ P8 & 2.05 \({}^{\text{b}}\)\(\pm\) 0.101 & 75.9 \({}^{\text{b}}\)\(\pm\) 0.142 & 18.1 \({}^{\text{a}}\)\(\pm\) 0.0221 \\ \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 5: Ash content, volatile compounds, and calorific value of tested biomass pellets. pellets [33]. Pellets made from forest biomass (common spruce) are characterized by a significantly lower amount of ash compared to pellets whose basic component is leafy biomass (raspberry and red currant) [44]. The raw material used for the production of pellets is the main factor that determines the calorific value of the solid fuel produced. According to the available literature, coniferous wood has a higher calorific value compared to hardwood [45]. Solid fuel pellets produced from waste of agricultural origin are characterized by a calorific value in the range of 16.72-17.70 MJ kg\({}^{-1}\)[33]. Scientists using household waste and raw material of wood origin made fuel mixtures whose calorific value oscillated around 16 MJ\(\cdot\)kg\({}^{-1}\). With an increase in the share of raw material of wood origin in the pellet, the calorific value increased [46]. The analysis of 20 types of solid fuels available in Europe showed that wood pellets made of coniferous raw material had a calorific value above 18 MJ\(\cdot\)kg\({}^{-1}\)[47]. The available studies show that the calorific values of the selected types of biomass are varied and amount to the following: for castor stalk, 14.6 MJ; for perry grass, 14.5 MJ; for rice husk, 15.1 MJ; for palm leaves, 15.4 MJ; and for saw dust, 17.7 MJ [14; 16]. Solid biofuels have a high volatile content, on average 67% [48]. Waste that is generated in the production of sunflower seeds and is used for energy purposes produces large amounts of volatile substances at a level from 70.4% to 77.1% [49]. Studies on pellets made from agricultural waste have shown that they have volatile matter from 64.54% [50] to as high as 87.75% [51]. Wood pellet made of Norway spruce wood was characterized by an amount of volatile compounds at a level of slightly higher than 82%. Much lower levels of volatile compounds were recorded for pellets produced from raspberry and blackcurrant biomass: 78.09% and 76.25%, respectively [44]. Other studies on wood biomass pellets indicate that 67.60% of volatile compounds were recorded during the combustion process [52]. The content of volatile compounds in green biomass varies, ranging from 41 to 77%, while wood biomass has a higher content of volatile compounds--up to 80% [10]. Table 6 presents the results of the percentage content of total nitrogen, total carbon, and hydrogen for individual solid fuels. The level of total nitrogen in the analyzed samples was quite even and ranged from 0.88% to 1.20%.