Biogas is basically a combination of methane and carbon dioxide naturally occurring in the earth's soils, or generated by the decomposition of organic waste generated during human activity. It's a clean, renewable energy source; it doesn't pose a serious environmental threat like other kinds of fuels such as coal and crude oil, and it is used in domestic, industrial and commercial settings to provide power and heat. This versatile fuel is relatively cheap and much of it is sourced as a byproduct of the waste management industry.
Scientists have shown that the gas is formed by bacteria breaking down organic matter in the soil, and converting it into methane and other waste products. When organic matter such as manure is decomposed, methane gas is produced as a byproduct. It's this gas that is the major cause of concern, because when it enters the atmosphere it acts as a powerful greenhouse gas that traps solar radiation close to the surface of the planet and raises global mean surface temperatures.
It's also known that excessive burning of biogas is partly responsible for the increase in atmospheric concentrations of carbon dioxide globally. Carbon dioxide is another problematic greenhouse gas that is released in greater volumes than methane, with potentially catastrophic effects on the environment. In addition, some research indicates that the vast majority of the Earth's methane is derived from livestock. Agricultural practices are said to produce up to 25% of the world's methane emissions.
While methane is thought to be one of the primary contributors to global warming, carbon dioxide is also known to play a role. Despite the fact it is much less potent than methane, it is the sheer volume of carbon dioxide emissions that we produce which causes the problem. It has been linked to the thawing of Arctic permafrost and ice sheets, as well as unstable weather patterns around the world ranging from extreme drought to floods and storms.
While it's clear what causes the release of methane emissions into the atmosphere, and one thing is known for certain: the release of this greenhouse gas into the atmosphere needs to be mitigated as much as possible to protect the environment and minimise the impacts of climate change. For those who work in gas production, treatment or management, it is important to be able to monitor gas production, composition and concentration within certain systems either by using a portable gas analyser or a fixed gas monitoring system.
So what is biogas and how does it affect us? This organic waste byproduct is usually formed during natural processes such as when plant matter decomposes on the forest floor, but it also takes place on a much larger scale in landfills around the world as organic waste such as household and agricultural waste decomposes. This foul smelling gas is highly flammable and is mostly made up from carbon dioxide and methane. When landfills are not sealed correctly, this byproduct not only adds methane to the air but also contaminates the air with other potentially dangerous byproducts such as sulfur dioxide and hydrogen sulfide.
One of the other byproducts of biogas is ethanol, which can be made from the sugars in the organic matter as it decomposes and breaks down. Ethanol is also produced through fermentation using milled cornstarch and can be used as a fuel additive for certain vehicles. There are also biofuels being developed that use biomass such as forest residues including sawdust from slash-and-grow processes. Biomass is considered by most to be a clean renewable energy source. Unlike fossil fuels, biogas does not deplete the nonrenewable resources of the earth.
How is this gas produced using anaerobic digestion? The bacteria that break down organic matter break down plant materials in landfills much like they do in the wild when they consume cellulose and release the carbon into the air. The process however is accelerated and takes place on a much larger scale than when organic matter is broken down within the environment. As well as the methane and other gases produced, decomposition also creates a portion of liquid waste which is often highly toxic. This liquid is the byproduct of the digestion of organic matter by the bacteria in the soil or in the landfill and must also be carefully managed to prevent pollution.