Understanding
Biogas: renewable energy
from organic waste
Learn the basics on how biogas works, and how anaerobic digestors (otherwise known as biogas systems) are the most efficient way to turn biogas into useful energy.
Author: Justin Morrissy, Hart Bioenergy Chief BioTech Officer
What is biogas?
Biogas is a renewable fuel made from organic waste.
It mainly consists of methane (CH₄) and carbon dioxide (CO₂), with small amounts of other gases like hydrogen sulfide (H₂S), ammonia (NH₃), and hydrogen (H₂).
The exact mix depends on the type of waste used and how it’s processed. Typically, biogas is 45-75% methane and 25-55% CO₂.
It can also be refined into biomethane, which is 95-99% pure methane, making it a cleaner alternative to natural gas.
Producing biogas with anaerobic digesters
Biogas is produced when microbes break down organic matter, like food waste or animal manure, in an oxygen-free (anaerobic) environment.
Anaerobic digestors (ADs) utilise this process by creating the ideal conditions for the microbes to produce the biogas, which is then captured for use.
Anaerobic digestors are one of the primary sources of biogas production and are the most energy efficient way to transform organic matter into methane.
Biogas is also naturally generated in places like landfills or waste ponds. In these cases, the gas can be captured and used for energy, or safely burned to prevent harmful emissions into the air.
Why use biogas?
Approximately one-third of edible food produced globally is wasted which adds up to about 1.3 billion tons each year.
Organic waste is a large and complex issue that costs the global economy hundreds of billions of dollars annually and accounts for up to 10% of global greenhouse gas (GHG) emissions.
By turning food waste and other organic materials into biogas we can significantly reduce both the economic and environmental cost of organic waste.
What are the benefits of capturing and utilising biogas?
Biogas production creates environmental and socioeconomic benefits by enhancing the local circular economies. The capture and use of biogas contributes to improved living standards, job creation, job stability, and emission reduction.
Specifically, the capture and use of biogas:
- Turns waste into valuable energy.
- Replaces natural gas or can be used to generate electricity.
- Helps prevent the release of methane into the air, reducing harmful GHG emissions.
- Lowers odours from waste.
- Can generate carbon credits.
In short, using biogas is a way to help the environment, reduce waste, and create economic opportunities.
Is biogas carbon neutral?
Biogas contains methane, which is a powerful greenhouse gas (GHG), and is at least 28 times more impactful than carbon dioxide.
When we capture and burn biogas, the methane instead turns into a less harmful carbon dioxide. This has 1/28th the harmful GHG effect that the methane would have if it was allowed to escape.
Burning biogas reduces its overall environmental impact, especially when it is used as an energy source to replace fossil fuels like natural gas.
So, when biogas is captured and used, it can be “carbon neutral” or even “carbon negative” – meaning it has either no negative impact on the environment or has an actively positive influence (by preventing the release of something that was going to harm the environment).
Even in less-than-ideal situations, using biogas is still more cost-effective and environmentally friendly than letting the gas go to waste.
What is biogas and biomethane used for?
Biogas and biomethane can be utilised as a clean energy source that replaces fossil fuels for:
- Generating electricity – biomethane can be used in a generator to generate electricity
- Heat generation – biogas and biomethane can be used as a heat source in multiple applications such as water heaters, boilers, heating homes and workplaces, and heat source for cooking
- Transport fuel -biomethane can be used as a fuel source in motor vehicles
Why choose biogas digesters?
Biogas digesters are an effective way of diverting organic waste away from landfills and waste ponds (where they will release harmful greenhouse gases), and utilising the energy for commercial operations, instead of buying in expensive and environmentally damaging grid-sourced electricity and natural gas.