Biogas
Biogas – general information
Landfill gas – is produced from biodegradable, organic fraction of communal waste, broken down into simple organic compounds. The process is aerobic in the first phase, and when another layer is fed, anaerobic conditions are created and the production of landfill gas is started. The composition of landfill gas includes: approx. 40-60% of methane, 40-50% of carbon dioxide, several percent of nitrogen, hydrogen sulphide, carbon monoxide, ammonia and other gases.
In optimum conditions, one tone of waste should produce approx. 400-500m3 of landfill gas, while in practice approx. 200m3 of gas can be obtained from landfill sites that are not organized to produce landfill gases.
Some typical examples of using landfill biogas include:
- Production of electrical energy in spark ignition engines, dual-fuel engines and turbines;
- Production of heat in adapted gas boilers;
- Production of electrical energy and heat in Combined Heat and Power plants;
- Supply of landfill gas to the gas supply system;
- Gas as car fuel.
Biogas from sewage sludge – is produced in the methane fermentation process from sludge produced during biological treatment of waste. The sludge is heated up and fed to a chamber, where gas is produced as a result of fermentation, which contains 60-70% of methane, 30-40% of carbon dioxide and trace amounts of other gases.
Methane can be used for the production of electrical energy and heat, mainly for in-house purposes of waste treatment plants. To be used in gas systems, biogas has to be dried and rid of hydrogen sulphide. Electrical energy is produced from biogas in gas power generators or in combined heat and power plants.
Agricultural biogas – raw materials for agricultural biogas power plants include liquid manure, farmyard manure, manure, crop residuals, diary waste, waste from sugar plants, slaughter houses, plant cuttings, organic waste and other waste.