How Does Biogas Work: A Beginner’s Guide

When people think of fuel, what comes to mind is usually gas or diesel that you put in your vehicle and propane or natural gas for your home. While these are efficient fuels that have been used for a long time and serve us well, there are other alternative sources that we can tap into. One of them is biogas, and it is a renewable fuel that is quickly gaining traction.

Have you heard of biogas? If not, it’s time to learn about this exciting fuel source. How does biogas work? Let’s find out.

Where Biogas Comes From

In short, biomass comes from biomass. C02, methane and other gases are produced from anaerobic digestion of organic material without oxygen. The thermochemical conversion of biomass happens when bacteria eat and break down, essentially digesting the biomass to produce the gas, and this bacteria naturally occurs in soil, bodies of water and the digestive tracts of humans and animals.

What is biomass, then? This is organic material from living organisms like plants and animals and includes:

  • Wood and agricultural products
  • Landfill
  • Solid waste
  • Alcohol fuels
  • Animal waste
  • Yard waste
  • Forestry residue

As biomass is converted into biogas, methane can be captured and left behind the organic nutrients for utilization in agriculture. The biogas system also has many other uses.

How to Collect Biogas

Biogas is readily available in garbage landfills, livestock manure holding ponds, and forestry operations and needs to be harnessed so it can be converted into energy through various methods, including:

Direct Combustion 

Burned directly for heating buildings and water and for producing electricity.

Thermochemical Conversion 

Decomposition of biomass feedstock material through pyrolysis and gasification.

Chemical Conversion 

With chemical conversion, transesterification converts grease, fatty acids, animal fats and vegetable oils to produce biodiesel.

Biological Conversion 

This is fermentation to convert biomass into ethanol and anaerobic digestion to produce natural gas.

These are some of the methods and industries that implement the collection and processing of biomass into biogas.

Biogas Plants

In a biogas plant, a facility can provide an oxygen-free condition for anaerobic digestion. This essentially turns waste into fertilizer and sustainable energy. The process includes the following:

Reception Area

Raw materials are brought in to be prepared for digestion. This includes seaweed, municipal and industrial sewage, livestock manure, food waste and paper waste as some of the materials.

Fermentation Digester Tank

This anaerobic digester uses fermentation to process biomass. Various types of materials are used and broken down at different rates. Agitators inside the air-tight tank help the fermentation, and the mixture is crushed down into small pieces and made into a slurry with the addition of water.

The mixture is heated, and the microbes go to work digesting the slurry and producing gas. This can take several weeks.

Gas Containment Holder

The holder collects gas that is produced and purified by removing any impurities and carbon dioxide. It can then be distributed for many fuel requirements.

Residual solids and liquids, called digestives, are separated and used in field fertilization and other landscaping and garden soil.

Water Treatment Plants

These facilities also use anaerobic digestion in their cleaning process and, in turn, use the gas for heat generation and energy. While this helps offset capital costs, most plants still flare off the gas.


Some landfills dig trenches and bury their waste to contain the anaerobic digestion. From there, they drill wells into the landfill, collecting up to 90% of the gases. It can then be pumped to a central facility for flaring, refining, or directly used for electricity and heat generation.


Some large farms also use techniques to harness the gasses from their biomass. They use biodigester systems, including:

  • Covered lagoons
  • Plug flow digesters
  • Complete mix digester

The gas is used for energy, and the solid effluent can be utilized for amending the soil.

The more companies that can implement these technologies, the more power they can harness and the less impact on the environment and atmosphere.

Renewable natural gas is a cleaner source of natural gas that can be utilized for electricity generation, fueling vehicles, heating and cooking while helping with waste reduction and management. It also limits pollution and turns literal trash and waste into viable and profitable energy for our future.

This is how biogas works, and it is developing and growing fast. The more we can utilize this discarded, raw resource and turn it into energy, the better we as a collective species become. While we are growing from burning wood and coal to fossil fuels and harnessing wind and solar, biogas is a commodity that is always available to be utilized. This brave new world can truly be recycled to power our future needs, which is exciting.

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