## 3 Results and Discussion  
The average values of the results obtained (from three replicates) characterizing the biofuels used are presented in Tables 1 and 2. The hemp biomass tested was characterized by comparable technical and chemical characteristics with the results of tests presented by other researchers assessing the usefulness of this plant for energy purposes [4; 10]. Particularly noteworthy here is the content of volatiles at the level of 69%, as well as relatively high, comparable to that for oak wood, combustion heat with an average value of 18.089 MJ\(\cdot\)kg\({}^{-1}\) and a low ash content at the level of 2.5% (Table 1). In terms of the parameters assessed, these values were also among the best biomass species for energy purposes [43; 44; 45], while the high content of volatile organic compounds indicated during research can improve the energy conversion efficiency in the case of fluidized fuel combustion [46]. The amount of hemp biomass yield was not analysed during the study. Data available in the literature [10] indicate that about 10 tons of hemp biomass from one hectare can be used for energy purposes. By comparing these data with the possibility of growing hemp in 2019 in the Lublin province, one can dispose of just over 100,000 tons of biomass, which contains (taking into account its heat of combustion, Table 1) 1.7 PJ of energy, which is equivalent to approximately 85,000 tons of hard coal with a calorific value of 20 MJ\(\cdot\)kg\({}^{-1}\). The improvement of the geometrical parameters of hemp biomass is obtained from the compacting process. Additionally, briquettes produced during the tests (Table 2) were characterized by desirable geometrical features, thus meeting the assumptions of appropriate quality standards [43; 44; 45]. Statistical analysis carried out between A and B type briquettes in terms of length, diameter, mass and density did not show significant differences with a probability p of 0.428, 0.727, 0.700 and 0.783, respectively. Only the observed difference between the analysed types of briquettes in terms of mechanical durability was confirmed statistically with a probability of p = 0.034. The visible impact of comminution on \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Symbol** & **Unit** & **Value** \\ \hline Total moisture & W\({}_{\text{t}}\)r & \% & 10.977 \(\pm\) 0.015 \\ Volatile parts & Vd & \% & 69.630 \(\pm\) 0.096 \\ Heat of combustion & Q\({}_{\text{s}}\)d & MJ\(\cdot\)kg\({}^{-1}\) & 18.089 \(\pm\) 0.034 \\ Calorific value & Q\({}_{\text{i}}\)d & MJ\(\cdot\)kg\({}^{-1}\) & 16.636 \(\pm\) 0.031 \\ Ash & Ad & \% & 2.51 \(\pm\) 0.135 \\  & Cd & \% & 43.366 \(\pm\) 0.276 \\ Elemental composition & Hd & \% & 6.669 \(\pm\) 0.040 \\  & Nd & \% & 0.248 \(\pm\) 0.049 \\  & Sd & \% & 0.056 \(\pm\) 0.002 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical and chemical properties of biomass of hemp. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Parameter** & **Symbol** & **Unit** & **Briquettes Type A** & **Briquettes Type B** \\ \hline Length & L & mm & 48 \(\pm\) 22 & 51 \(\pm\) 13 \\ Diameter & D & mm & 52 \(\pm\) 0.5 & 53 \(\pm\) 0.5 \\ Mass & m & kg & 86.75 \(\pm\) 44.89 & 93.51 \(\pm\) 30.91 \\ Bulk density & – & kg\(\cdot\)m\({}^{-3}\) & 828 \(\pm\) 71 & 818 \(\pm\) 82 \\ Mechanical durability & DU & \% & 98.17 \(\pm\) 0.25 & 97.57 \(\pm\) 0.21 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physical properties of briquettes made of hemp. the mechanical durability of hemp biomass briquettes was also demonstrated during studies by [PERSON] et al. [22], as well as during research on the compaction of other raw materials [47].