Biogas
What is biogas?
Biogas is a gas that can be used for many purposes and is formed by the breakdown of organic matter that does not have an oxygen source and in turn a gas that is part Methane and part Carbon Dioxide is formed. Landfill sites are huge producers of biogas due to the large amounts of waste material that gathers and is then broken down by bacteria. It is the lack of oxygen that causes the “anaerobic conditions” which produce the gas and it has been observed as far back as the 13th century when Marco Polo noticed that the Chinese covered sewage tanks in order to capture the gas to create power.
How is biogas produced?
Biogas is produced by the breakdown of organic material when no oxygen is present. The actual type of biomass material that is being broken down will determine what sort of gas will be created, although it is typically a mix of CO2 and Methane with trace elements of Nitrogen, Hydrogen, Hydrogen Sulphide and Siloxanes.
There are other factors that can determine the production of biogas. These include the presence of low or high heat sources, the toxicity of the biogas source material and the PH levels, and the general amount of biogas source material.
Biogas occurs naturally by the anaerobic digestion of the following types of waste –
- Animal manure
- Crops
- Garden waste
- General biomass material
- Human sewage waste
- Landfill waste
- Municipal waste
- Plant waste
- Sludge from wastewater
Uses of biogas?
Methane is a main component of biogas, methane is also a main component of natural gas, therefore, biogas can substitute the use of natural gas in various areas such as heating, cooking, automobile fuel, electricity generation, etc.
The main use of biogas is as a fuel source.
Biogas can be used as a fertilizer.
Power plants can be used to process biogas to generate power.
Biogas is a natural by-product of numerous types of decaying waste so it is important that we harness the biogas when we can. For example, Methane is a harmful greenhouse gas (much more so than CO2) so it is important that in areas such as landfill sites where there is mass creation of biogas we capture the gas and put it to good use in powering products and services rather than allowing the harmful biogas to escape into the atmosphere and cause possible damage to the ozone layer.
Advantages of biogas
Biogas naturally occurs as a consequence of decaying matter. If there is anaerobic digestion of suitable matter then there will be a source of biogas available so we should use it where we can.
It is a cheap and renewable source of fuel.
The gas can be captured direct from the biogas source so this represents a decentralised form of power generation.
It is a clean type of fuel in the sense that we capture the biogas at source before it is released into the atmosphere – it is only the burning of the fuel that will actually lead to the release into the atmosphere.
The technology required to capture biogas is not as expensive as the technology required to create other types of biofuels such as bioethanol or biodiesel.
Household waste is disposed of and used in an environmentally responsible manner.
Disadvantages of biogas
Biogas is limited by scale of the source material. It is in our interests to have the least waste possible so it is unlikely that biogas production will be able to scale to such a volume in the future that would lead to large scale energy production benefits.
The efficiency of biogas production systems is difficult.
There are some inherent gas impurities in the biogas compound that can lead to difficulties in implementing biogas as a fuel into combustion engines – the impurities can lead to engine corrosion.
Economically it is unlikely that companies will want to work on biogas capture programs because there are much more profitable areas of energy production, even within the small biofuels sector.