# Biomass from Green Areas and Its Use for Energy Purposes
## 1 Introduction  
The demand for electricity is constantly growing, and it is caused by civilization and technical progress. Currently, fossil fuels cover about 80% of the world's energy demand [1]. Fossil fuels in the future will not be sufficient to cover the energy demand, therefore the future for the global economy may be renewable energy sources, which include, among others, energy from biomass [2]. Biomass is the oldest and most widely used renewable energy source. It is possible to convert biomass into various types of biofuels or energy using thermal, physical, and biological processes [3, 4]. Biomass is a fuel that is easy to obtain and process. Biomass energy conversion technologies are relatively cheap, simple, and failure-free. Taking into account the environmental aspects in particular, there has been a continuous increase in obtaining energy from biomass using various technologies [5]. The promotion of the use of energy from renewable sources is included in the European Union Directive of 23 April 2009. This document defines the term biomass. According to this legal act, biomass is biodegradable waste or residues of biological origin from agriculture or forestry, as well as municipal waste of plant or animal origin [6]. The currently implemented energy strategy of the European Union is aimed at minimizing the harmful effects of energy technologies on the environment, keeping energy prices at their lowest possible level, and maintaining the security of the energy supply [7]. In accordance with the Green Book \"Framework for climate and energy policy until 2030\", in order to avoid further degradation of the environment, it is necessary to gradually abandon conventional energy sources and increase the share of renewable energy sources [8]. Changes in the energy market resulting from the abandonment of conventional energy sources have now resulted in an increase in its prices. In addition, there have also been cases of negative impact of RES (renewable energy sources) on the operation of power systems. The recommended solution is to increase the share of biomass in energy conversion processes. The result of this action will be the preservation of the durability of the conventional system, taking into account the environmental protection resulting from the EU energy policy [9]. There are many types of biomass, such as wood and wood biomass, herbaceous biomass, aquatic biomass, and animal and household waste, which can be used to produce electricity and heat. Table 1 presents the current state of knowledge on the parameters determining the quality of biomass used for energy purposes. On the other hand, Table 2 presents a list of selected raw materials used for the production of biofuels and their calorific values. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Type of Biomass** & **C** & **H** & **N** & **S** & **Volatile Compounds** & **Ash** \\  & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** \\ \hline Wood and woody biomass & 49–57 & 5–10 & \textless{1–}1 & \textless{1–}1 & 30–80 & 1–8 \\ \hline Herbaceous biomass & 42–58 & 3–9 & \textless{1–}3 & \textless{1–}1 & 41–77 & 1–19 \\ \hline Aquatic biomass & 27–43 & 4–6 & 1–3 & 1–3 & 42–53 & 11–38 \\ \hline Animal and human waste biomass & 57–61 & 7–8 & 6–12 & 1–2 & 43–62 & 23–34 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of biomass used for energy purposes [10].