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What is a Biogas Generator?

With Australians throwing out around 4 million tonnes of food every year, it is crucial that we start considering more effective and environmentally friendly waste options for a sustainable future. Enter the biogas generator, also known as a biogas digester, a concept that has been around for hundreds of years for the productive utilisation of waste products. It draws on eco-friendly and sustainable concepts to produce biogas through the breakdown of organic matter, meaning less waste and more usable products for a variety of applications. A biogas digester is like a housing system for biogas production, allowing the process to go along without unwanted interference from outside influences.


Inoplex designs and builds combined heat and power generators in Australia for various renewable fuels, including biomass and biogas. They can also be fuelled by natural gas or LPG if you do not currently have renewable energy on your site and wish to convert later.

If you are searching ‘biogas generator’ you may also find however that there is another possible meaning – a generator which is actually run on biogas. This definition suggests that the biogas has already been created and it is now being used to power a generator, as opposed to the other meaning suggesting it is the structure which helps create biogas. Make sure you are clear when you are talking to a professional as to what you need, you don’t want a mix-up!

Food Waste for Biogas
Breakdown of Organic Matter

What is biogas?

Starting at the beginning, biogas is the gas which is produced when organic matter is broken down in an anaerobic environment – ie. an environment that is without oxygen. Biogas is made up mostly of carbon dioxide and methane and can be used in a very similar way to natural gas. Examples of organic material than may be broken down include livestock manure, plant waste and food scraps, which offers a beneficial alternative for the use of waste as opposed to the dumping of rubbish in landfills or other rubbish-collecting areas.

What is a biogas generator?

A biogas generator, or biogas digester, is a structure that contains a large tank for the storage of organic waste matter (basically anything that can rot, besides wood, can go in there!). The tank contains bacteria that do not require air to survive, and they break down the organic waste through a temperature controlled four stage process :

  1. Hydrolysis – the first stage in digestion involves the breakdown of huge organic polymers, which are a common occurrence in organic waste. This is an essential step in anaerobic digestion, as hydrolysis breaks up fats, proteins and carbohydrates into smaller molecules such as simple sugars, fatty acids and amino acids. Some products from this stage will be used in methanogenesis later on however most will require further breaking down in acidogenesis
  2. Acidogenesis – the second stage of anaerobic digestion sees fermentative bacteria continuing to breakdown the organic waste, producing an acidic environment with traces of ammonia, H₂, H₂S, CO₂, shorter volatile fatty acids, carbonic acids and alcohols, among other things. Despite this, a lot of the polymers are still too large and unstable to be used to create methane, and require further breaking down
  3. Acetogenesis – the next step is the creation of a derivative of acetic acid, known as acetate, by acetogens from carbons and other energy options. A lot of substances created in acidogenesis are catabolized during this stage, creating acetic acid, H₂ and CO₂. Acetogens are quite clever in that they breakdown the organic matter to an appropriate level for methanogens to do their job of creating biofuel
  4. Methanogenesis – this is the final stage of digestion, in which some of the hydrolysis and acidogenesis products are combined with the final acetogenesis products to allow methanogens to create methane. There are two processes in which methane can be produced during this final digestion stage :

          CO₂ + 4 H₂ → CH₄ + 2H₂O 

          CH₃COOH → CH₄ + CO₂

The second pathway, using acetic acid, is generally the main way to create methane in methanogenesis.

This digestion results in the production of biogas and decomposed waste. The biogas is then transferred out of the generator to be utilised in other ways and become fuel and the decomposed waste can be used as a natural fertiliser.

Who can use a biogas generator?

Anyone who has enough space for one! Due to the size of the tank needed, and the fact they are a permanent installment, biogas digesters need a bigger-sized yard to be placed in. In saying this, there are differing sizes of systems however the smallest option is still quite large. Some people even have multiple generators on their property, depending on the size of the land and the amount of biogas needed.

Who can use a biogas generator?

What are the benefits of a biogas generator?

There are quite a few benefits to a biogas generator, but the main ones are :

  1. A large reduction in energy costs
  2. Eco-friendly use of waste
  3. Lower installation costs than other renewable energy options
  4. Lower greenhouse gas emissions
  5. Lower amounts of waste going to landfills
  6. Production of natural fertiliser

This list is not exhaustive, so do a little bit of research yourself and you will be amazed at the great benefits a biogas generator can offer your home!

Biogas Generator

If you have any questions relating to biogas generators, or are curious to know if you can have one installed in your home or business, give Inoplex a call on 0448 307 282 or complete an online enquiry form today. We are a team of qualified professionals who pride ourselves on our extensive industry knowledge and experience, so contact us today and we can answer your questions and discuss the best sustainable options for you.