## 5 The Use of Hemp Biomass for Biofuels Production
Due to its high cellulose and low lignin content, hemp has promising potential for bioethanol production. The co-production of ethanol and methane has a slightly reduced yield (163-188 L-Mg\({}^{-1}\)), but it also provides 175-181 m\({}^{3}\).Mg\({}^{-1}\) of methane as a by-product. Similar amounts of bioethanol are obtained from hemp as from _Hibiscus canmabinus_, _Panicum virgtatum_, and _Sorghum_, but these plants are characterized by greater profitability while co-producing grain [86; 87]. The research on the new 'Henola' hemp cultivar showed that the yield of straw ranged from 10.6 Mg\(\cdot\)ha\({}^{-1}\) to 11.3 Mg\(\cdot\)ha\({}^{-1}\)--in the case of the control object and using complex fertilization with NPK, respectively. In the analyzed samples, the average content of cellulose was 35.5%, holocellulose was 68%, and hemicellulose was 32%. In turn, the amount of lignin turned out to be independent of the type of fertilization. The lowest bioethanol content, 7.11 g\(\cdot\)L\({}^{-1}\), was found for hemp fertilized with NPK, and the highest, 9.93 g\(\cdot\)L\({}^{-1}\), for hemp fertilized with P and K, for which the ethanol yield converted to straw yield was 2.7 m\({}^{3}\).ha\({}^{-1}\)[88]. In other studies about the optimizing chemical and enzymatic treatment of Henola's biomass, an ethanol content of 10.51 g\(\cdot\)L\({}^{-1}\) was obtained [89]. The so-called 'first generation' biofuels, which are produced from starch and sugar, do not seem to be a sustainable solution due to the potential burden that their production places on the food industry. 'Second generation' biofuels, made from inexpensive and abundant plant biomass, are seen as a much more attractive option. However, the full use of their potential still requires overcoming many technical problems [90]. Biogas is produced during the transformation of biomass in anaerobic biological processes [91]. The most frequently used and most effective method of biogas production in industrial conditions is methane fermentation. It is carried out under strictly defined conditions in special reactors [92]. The resulting gas mixture consists of about 2/3 methane and about 1/3 carbon dioxide [75; 93]. Many different organic substrates are used for the production of biogas. Biomethane is most often produced from maize silage and animal manure. Increasingly, biowaste and waste plant biomass are also used for this purpose [94; 95]. The possibilities of producing fuels from plant biomass are the subject of intensive research and have been implemented for years. The results of this work clearly indicate that this is a prospective direction that already brings measurable benefits to both the environment and agricultural producers. However, it requires further research in order to optimize biofuel production processes as well as search for biomass sources that are most favorable in terms of energy efficiency and at the same time have the least impact on the environment. Industrial hemp biomass can also be used to produce biogas. _Zea_, \(\times\)_Tritcoscale_, _Helianthus_, and _Sorghum_ are energy crops often used as raw materials for processing in anaerobic fermentation processes, mainly due to their high biogas potential. Hemp cultivation has negative environmental impacts due to changes in land use. Therefore, it is important to look for alternative species with a lower environmental impact that allow the production of comparable amounts of biogas with similar energy efficiency. Industrial hemp is a highly competitive raw material in relation to the currently used energy crops [96]. From one hectare of hemp cultivation of the Henola variety, 630 m\({}^{3}\) to 783 m\({}^{3}\) can be obtained, depending on the sowing density [20]. Worth noting is also the topic of fifth-generation fuels from in vitro cultures. Currently, this method of obtaining biofuels is perceived as one of the most promising and environmentally friendly.