What is biogas? Biogas is a combination of gaseous substances, mostly consisting of carbon dioxide and methane, produced during the breakdown of organic materials, mostly coming from crops, animal waste, municipal solid waste, domestic waste or agricultural produce. It is an energy source with high reliability and renewability. However, the question of what biogas is still remains a mystery to most people. This article aims to shed light on this important topic and explain what it is, the advantages of using it and its limitations.
Biogas is produced through the digestion of organic materials such as foods or organic waste. The break-down of these materials releases methane, a highly volatile gas that can cause severe respiratory problems and health complications, especially in cases where there is not sufficient oxygen present in the air. However, methane gas is a highly abundant substance existing in the Earth's atmosphere and in normal concentrations it doesn’t tend to pose a risk to human health.
How does decomposition produce methane? During the digestion of organic matter by bacteria, a process called denitrification occurs, causing methane to be formed if there is enough time for the organic matter to break down completely. The major components in biomass that can release methane are lignin, cellulose and the mixed amino acids found in fats and proteins.
Why is biogas used as a fuel?
Biogas systems are used as a means of producing alternative fuels because they can replace fossil fuels like petroleum and coal in several countries. In addition to this, biogas systems can also reduce the overall greenhouse gas emissions as they prevent methane from escaping landfills and directly entering the atmosphere. Another significant benefit of using biogas as fuel is that it can be produced more efficiently than the commonly used fossil fuels and burns much more cleanly, therefore having a smaller environmental impact.
How is biogas created?
There are two main processes responsible for biogas production in biogas upgrading and collection systems: aerobic and anaerobic digestion of waste by bacteria. In the aerobic stage of biogas production, the organic matter that is broken down will be mixed with oxygen in a warm, humid environment. This mixture will undergo the process of oxidation, which will then release carbon dioxide and water. The anaerobic stage of biogas production on the other hand, produces methane gas by breaking down organic matter without mixing with the oxygen in the air.
What are the benefits of using biogas?
The primary benefit of biogas production is that it is cleaner than fossil fuels. When biogas comes from anaerobic digesters, it contains carbon dioxide and methane as its two main components. These chemicals are what make up the gas and if allowed to enter the atmosphere they have the effect of contributing to net heat gain which raises the global mean surface temperature.
Biogas can be very efficient in its use. It takes less energy to produce and gives us a useful purpose when it comes to managing waste products. It is also considered to be a sustainable energy source because the feedstock used to produce it is free and usually collected municipally. The energy released through biogas use can actually help offset most of the greenhouse gas emissions that are produced through using other combustible fuels. These benefits have led to an increase in the demand for this biogas.
Are there any drawbacks to using biogas?
Biogas is still a source of methane gas, which is a much stronger greenhouse gas than carbon dioxide - it is up to 30 times more potent. Where sources of methane are not correctly managed, air pollution can occur through leaks in the gas collection, transportation and storage systems.
Are there any other uses for biogas?
Perhaps surprisingly, you can feed your plants with biogas. There are a number of commercial fertilisers and nutrients available on the market that are made from landfill gas that can be fed to plants to increase their yields and provide them with extra nutrition. Making fertiliser in this way is more eco friendly than other methods as it relies on waste and byproducts rather than sourcing new, virgin materials. Repurposing substances such as landfill gas in this way is one of the best ways to combat rising levels of commercial and domestic waste.
Resources:
Methane Monitoring - GitBook
Groundwater Extraction - Hashnode
Portable Gas Analyser - Oregon State University
Landfill Gas Monitoring - Portfolium
Biogas Monitoring - Slides
Biogas Monitoring - Substack
Biogas Upgrading - Temple University

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