What is BioGas
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas is comprised primarily of methane and carbon dioxide. Biogas originates from biogenic material and is a type of biofuel. Biogas is a product of the anaerobic digestion or fermentation of biodegradable materials such as manure or sewage, municipal wasteand energy crops. The methane in biogas gives it the ability to be used as a fuel. The combustion of which releases energy.
Basic information on biogas
1. Composition of biogas produced in anaerobic biogas reactors
Table 1. Average composition of reactor biogas.
Matter
%
Methane, CH 4
55-75
Carbon dioxide, CO 2
25-45
Carbon monoxide, CO
0-0,3
Nitrogen, N 2
1-5
Hydrogen, H2
0-3
Hydrogen sulfide, H 2 S
0,1-0,5
Oxygen, O 2
traces;
2. Landfill gas composition
Table 2. Average composition of biogas recovered at a landfill (landfill biogas).
Matter
Content
Methane, CH 4
54 %
Carbon dioxide, CO 2
42 %
Oxygen, O 2
0,8 %
Nitrogen, N 2
3,1 %
Chlorine (total 2 )
22 mg/ m³
Fluor (total F 2 )
5 mg/ m³
Hydrogen sulfide, H 2 S
88 mg/m³
Calculation of the energy from biogas
Calculation of the thermal value of the recovered biogas (methane 65%) 
If reactor produces 2000m³ of biogas per day, the contained heat capacity may be calculated as follows: 
Operating efficiency of the utilisation of the produced biogas effects decisively the amount of the energy produced.
- Operating efficiency if only heat is produced - 90 %
- Operating efficiency if both electricity and heat are produced - 85 % (35 % electricity and 50 % heat)
- Operating efficiency if only electricity is produced - 35 %
If a biogas plant uses all the produced biogas for joint production of energy and heat, the amount of energy produced during a day will total 10.94 MWh 
