Biogas

What is Biogas?

Biogas is a combustible gas composed mainly of methane and carbon dioxide. The principal component of biogas, Methane, gives the biogas its combustion properties.

Biogas is produced during the microbiological decomposition of organic material in anaerobic (oxygen free) conditions.

Biogas can also be produced from organic wastes, slurry, manure or solid waste as an end result of the methane fermentation and anaerobic digestion of the humid biomass.

How does a biogas installation work

A biogas plant transforms biodegradable substrates into electricity and heat. The key elements and steps involved in a biogas plant are:

• The Homogenization and input of substrates into the digesters.
• Desulfurization systems.
• Combined Heat and Power Unit.

The technique used for feeding in and homogenizing substrates will vary according to the individual characteristics of the raw material (pumping, worm conveyors, etc.). The digesters are cylindrical deposits (cement or steel) with shaker and heating systems that ensure optimum conditions for methanogenesis (a form of anaerobic digestion). The resulting biogas is accumulated inside a gasometre (either directly installed in the upper section of the digestor or installed as a separate unit) Once the Hydrogen sulphide (H2S) has been eliminated using a desulfurization and condensation system, the biogas is channelled to a combined heat and power unit where it is transformed into heat and power. The generated electricity can either be sold to the grid or be self-consumed, with the heat covering the plant's own demand and with the excess heat made available for external heating or industrial systems.

A by product of the production of biogas is the production of digestate. Digestate is the metabolized organic material rich in inorganic nutrients, and as so is for application as an organic soil amendment..

Other ways biogas is used

There are several ways to use biogas to utilise its contained energy. It can be transformed into biomethane by eliminating its carbon dioxide content (CO2), giving it similar qualities to natural gas. The biomethane is then conditioned and can be used in the following ways:

• It can be fed into the natural gas distribution grid.
• It can be used as a biofuel.
• It can be burned in Combined Heat and Power engines.