Biogas is produced with an anaerobic method, which involves live digestion of biomass in an oxygen-free environment. The second part of our book gives information about algae technology of the anaerobic process, which produces biogas by a biological process using animal fertilizers, food waste, and bioenergy products. In general, biogas can be used to produce heat and electricity, and its addition to the natural gas network is even considered as a vehicle fuel. It consists of 30-40% CO2 as content, 45-65% CH4. Conversion of CH4, which is 20 times more harmful than CO2 as a greenhouse gas, into energy is essential for the protection of environmental impact. In this sense, the burning of biogas emerges as a greenhouse gas reduction strategy.