Biogas production
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas originates from biogenic material and is a type of biofuel. Biogas is produced by anaerobic digestion or fermentation of biodegradable materials such asbiomass, manure, sewage, municipal waste, green waste, plant material and energy crops. This type of biogas comprises primarilymethane and carbon dioxide. Other types of gas generated by use of biomass is wood gas, which is created by gasification of wood or other biomass. This type of gas consist primarily of nitrogen, hydrogen, and carbon monoxide, with trace amounts of methane.
The gases methane, hydrogen and carbon monoxide can be combusted or oxidized with oxygen. Air contains 21% oxygen. This energy release allows biogas to be used as a fuel. Biogas can be used as a low-cost fuel in any country for any heating purpose, such as cooking. It can also be used in modern waste management facilities where it can be used to run any type of heat engine, to generate either mechanical or electrical power. Biogas can be compressed, much like natural gas, and used to power motor vehicles and in the UK for example is estimated to have the potential to replace around 17% of vehicle fuel. Biogas is a renewable fuel, so it qualifies for renewable energy subsidies in some parts of the world.
Production
Biogas can be produced utilizing anaerobic digesters. These plants can be fed with energy crops such as maize silage or biodegradable wastes including sewage sludge and food waste. During the process, an air-tight tank transforms biomass waste into methane producing renewable energy that can be used for heating, electricity, and many other operations that use any variation of an internal combustion engine, such as GE Jenbacher gas engines. There are two key processes: Mesophilic and Thermophilic digestion.
Landfill gas is produced by wet organic waste decomposing under anaerobic conditions in a landfill. The waste is covered and mechanically compressed by the weight of the material that is deposited from above. This material prevents oxygen exposure thus allowing anaerobic microbes to thrive. This gas builds up and is slowly released into the atmosphere if the landfill site has not been engineered to capture the gas. Landfill gas is hazardous for three key reasons. Landfill gas becomes explosive when it escapes from the landfill and mixes with oxygen. The lower explosive limit is 5% methane and the upper explosive limit is 15% methane. The methane contained within biogas is 20 times more potent as a greenhouse gas than carbon dioxide. Therefore uncontained landfill gas which escapes into the atmosphere may significantly contribute to the effects of global warming. In addition landfill gas' impact in global warming, volatile organic compounds (VOCs) contained within landfill gas contribute to the formation of photochemical smog.
Applications
Biogas can be utilized for electricity production on sewage works, in a CHP gas engine, where the waste heat from the engine is conveniently used for heating the digester; cooking; space heating; water heating; and process heating. If compressed, it can replace compressed natural gas for use in vehicles, where it can fuel an internal combustion engine or fuel cells and is a much more effective displacer of carbon dioxide than the normal use in on-site CHP plants.
Greenetik Vortex® - Biogas ring fermenter system
The Greenetik Vortex® ring fermenter is a biogas system of the 3rd generation. This plant type has been specifically developed to the needs of Central and Eastern Europe.
The advantages of the ring system is the flexibility in the use of various substrates. This is a great advantage for operators with a high share of manure to the share of renewable raw materials. The Vortex® - ring system is able to homogenize various substrates in the fermenter. This has a positive influence on the biogas production.
Ring systems are available from a size of 250 kW to several MW.
High economic and operational safety
- Up to 30% less power consumption than conventional natural biogas plants
- Up to 30% less specific heat consumption compared to conventional biogas plants
- Faster payback through lower internal energy intake
- The ring system ensure the homogenization of the substrates
- Prevent the formation of a crust by the agitator geometry
- And much more
Vortex® biogas plant scheme
- Primary fermenter
- Secondary fermenter
- Slurry store for the liquid phase
- Feeding system for the solid phase
- External gas holder
- Operation building with CHP
- Storage for separator (optional)
- Separator (optional)
- Storage facility for solid phase (optional)
- Final storage / Lagoon
