# Biochar as a Multifunctional Component of the Environment--A Review
## 4 Biochar in Environmental Conservation  
The use of biochar in environmental protection falls within the scope of remediation of polluted soils, energy production, climate change aspects, waste management, sustainable development issues. Production of biochar is one of the methods permitting the reduction of the need for the disposal of animal and plant waste. Biodegradable animal waste, agricultural biomass and sewage sludge can be effectively used for the production of energy through pyrolysis. Additional benefits include a reduction in the volume of waste subjected to thermal processing, as well as the elimination of pathogenic microorganisms potentially occurring e.g., in cattle manure and sewage sludge. The use of the above waste material in the production of biochar may also lead indirectly to the reduction of methane emissions from landfills and reduce the necessity of seeking alternative methods of waste management [67]. Increased emissions of CO\({}_{2}\) to the atmosphere in recent years have led to a significant disproportion between the natural emission and absorption of carbon. It is necessary to take action to balance carbon in the atmosphere by its capture and storage e.g., in the soil [68]. One of the solutions to this problem involves the use of biochar obtained from various types of biomass. Introduced into the soil, it enables the long-term sequestration of carbon. According to the literature, by adding biochar to soil at a rate of 13.5 t ha\({}^{-1}\) it is possible to store the carbon within it for a minimum of two hundred years [69]. Furthermore, it has been shown that biochar may lead to a decrease in emissions of nitrous oxide (N\({}_{2}\)O) and methane (CH\({}_{4}\)) from the soil, mediated by biotic and abiotic mechanisms [70]. One of the main applications of biochar is its use as a renewable fuel [71; 72; 73]. Carbonization products can be incinerated or co-incinated in combined heat and power plants and power plants. Biochar in comparison with raw biomass contain less of significant amounts of chlorine, and volatile substances influencing the reduction of boiler efficiency and increased emission of inorganic particles. Changes in chlorine content result from the specificity of the pyrolysis process. During pyrolysis, the chlorine contained in the raw biomass is released in gaseous form and goes to the environment. These changes result from the changing structure of the material and the processes of degassing biomass. Inorganic compounds forming fine particles result in increased sludge production in fuel-burning boilers. This problem disappears in the moment of carbonization of a fuel, which is particularly important in the processes of biomass combustion. Biochar is therefore an important element in reducing this disadvantage [74]. Such fuels are an alternative to conventional fossil fuels (Table 4), as well as they offer the possibility of recovering energy from waste deposited in landfills [2]. An additional direction of wide use of biochar in the power industry is the acquisition of many energy products during its production. Additionally, obtained electricity and heat may successfully reduce the costs of the process and creation of cogeneration installations, which may become an important element in the creation of local power grids. Such small installations on the local market quickly and efficiently process e.g., waste from agricultural production, which creates independent power systems essential for the elimination of power and climate risks [33]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Fuel**} & \multirow{2}{*}{**Calorific Value (MJ kg\({}^{-1}\))**} & **Carbon** & **Ash** & **Volatiles** \\ \cline{3-5}  & & & **\%** & \\ \hline \multicolumn{5}{c}{Fossil fuels} \\ \hline Natural gas & 48.0 & 75.0 & 0.0 & 100.0 \\ Lignite & 25.0 & 60.0 & 12.0 & 25.0 \\ Bituminous coal & 7.5–21.0 & 66.0–73.0 & 10.0–20.0 & 40.0–60.0 \\ \hline \hline \end{tabular}
\end{table}