## 3 Results and Discussion
### Elemental Analysis
In summary, the energetic characteristics of biochars derived from broom and gorse with pyrolysis at 300 or 600 \({}^{\circ}\)C are appropriate materials for fuel and energy production. The HHV and LHV of broom- and gorse-derived biochars are comparable of those obtained in investigations by [PERSON] et al. [61], who reported an LHV of 18.88 MJ kg\({}^{-1}\) and an HHV of 20.04 MJ kg\({}^{-1}\) for low-grade sub-bituminous coal and by [PERSON] et al. [82] for conventional fuels like bituminous coal, lignite/brown coal, and coal water slurry, with HHVs of 27.11, 17.33, and 14.03 MJ kg\({}^{-1}\) respectively; these values are within the range of variation in the materials in this study (Table 3). Lignite, a coal similar to the biochars according to the Van Krevelen diagram, had an HHV of between 9.3 and 19.3 MJ kg\({}^{-1}\) at 300 \({}^{\circ}\)C [63]; meanwhile, for the biochars at 600 \({}^{\circ}\)C, the most similar conventional fuel was anthracite (Figure 1). Anthracite has an HHV of 33.58 MJ kg\({}^{-1}\)[76] and an LHV of 26.71 MJ kg\({}^{-1}\)[77] and 27.47 MJ kg\({}^{-1}\)[78]. In this scenario, the biochars had a greater HHV at 300 \({}^{\circ}\)C than those reported in the literature  
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & \begin{tabular}{c} **Average HHV** \\ **(M] kg\({}^{-1}\))** \\ \end{tabular}  & **LHV (MJ kg\({}^{-1}\))** & **CDF** & **EEF** & **CVI (\%)** & **ED (MJ \(\mathbf{m}^{-3}\))** \\ \hline BROOM & 15.57 \(\pm\) 0.25 a & 14.28 \(\pm\) 0.21 a & - & - & - & 4359.15 \(\pm\) 69.41 d \\ BB300-1H & 23.06 \(\pm\) 1.07 b,c & 21.91 \(\pm\) 1.07 b,c & 1.4 \(\pm\) 0.05 b & 1.48 \(\pm\) 0.07 b,c & 48.14 \(\pm\) 6.89 b,c & 4151.29 \(\pm\) 192.96 c,d \\ BB300-3H & 24.18 \(\pm\) 1.08 c & 23.1 \(\pm\) 1.05 c,d & 1.48 \(\pm\) 0.05 b & 1.55 \(\pm\) 0.07 c & 55.3 \(\pm\) 6.91 c & 4351.88 \(\pm\) 193.64 d \\ BB600-1H & 22.62 \(\pm\) 0.51 b,c & 22.19 \(\pm\) 0.48 b,c & 1.62 \(\pm\) 0.02 c & 1.45 \(\pm\) 0.03 a,b,c & 45.31 \(\pm\) 3.25 & 5429.27 \(\pm\) 121.36 e \\ BB600-3H & 21.69 \(\pm\) 1.33 b & 21.35 \(\pm\) 1.31 b & 1.6 \(\pm\) 0.07 c & 1.39 \(\pm\) 0.09 a,b & 39.35 \(\pm\) 8.55 a,b & 5423.48 \(\pm\) 332.81 e \\ GORSE & 17.02 \(\pm\) 0.7 a & 15.67 \(\pm\) 0.68 a & - & - & - & 3914.25 \(\pm\) 160.17 b,c \\ BG300-1H & 22.73 \(\pm\) 0.74 b,c & 21.52 \(\pm\) 0.78 b,c & 1.3 \(\pm\) 0.05 a & 1.34 \(\pm\) 0.04 a & 33.56 \(\pm\) 4.37 a & 3636.84 \(\pm\) 118.99 a,b \\ BG300-3H & 24.21 \(\pm\) 0.53 c & 23.12 \(\pm\) 0.55 c,d & 1.4 \(\pm\) 0.03 b & 1.42 \(\pm\) 0.03 a,b & 42.26 \(\pm\) 3.09 a,b & 3389.41 \(\pm\) 73.55 a \\ BG600-1H & 23.61 \(\pm\) 1.46 c & 23.22 \(\pm\) 1.4 c,d & 1.6 \(\pm\) 0.05 c & 1.39 \(\pm\) 0.09 a,b & 38.71 \(\pm\) 8.6 a,b & 4013.01 \(\pm\) 248.95 c,d \\ BG600-3H & 23.71 \(\pm\) 1.06 c & 23.34 \(\pm\) 1.05 d & 1.61 \(\pm\) 0.05 c & 1.39 \(\pm\) 0.06 a,b & 39.34 \(\pm\) 6.2 a,b & 4031.44 \(\pm\) 179.5 c,for lignite coal; for biochars at 600 \({}^{\circ}\)C, the HHVs were below the HHV and LHV ranges of anthracite. Therefore, all biochars showed HHV values greater than 20 MJ kg\({}^{-1}\), which ensures auto- thermal combustion [83]. It could be concluded that the biochars obtained from the pyrolysis of broom and gorse are suitable as fuels, given their adequate energy indices (Table 3). Subsequently, the production of biochars from these biomass waste could provide an adequate valorization technology for cleaner and renewable energy production compared to conventional fossil fuels (i.e., anthracite, lignite, bituminous, or sub-bituminous coal).