The Lowdown on Methane - Sources, Detection & Uses

Characterised by the chemical symbol CH4, methane is a naturally occurring gas that is composed of one carbon atom and four hydrogen atoms. It’s found throughout out the world, including in all four of the alchemical elements in the environment, and its existence predates human activity by millennia. Nonetheless, it has become something of a concern in recent years due to its association with climate change.

That’s because although there are a variety of natural sources of methane emissions on the planet, the concentrations of the gas have skyrocketed in the last 200 years or so. Indeed, the most advanced monitoring models now tell us that the current levels of methane in our atmosphere are more than double what they were prior to the Industrial Revolution, indicating that anthropogenic activity has caused the upsurge. This is a problem due to methane’s role as a greenhouse gas, which effectively traps heat in the Earth’s troposphere and contributes to the twin problems of global warming and climate change. In this article, we’ll examine its sources, effects, detection methods and potential uses as a viable commodity.

Although this article aims to provide a thorough introduction for newcomers to the gas, those interested in a more in-depth and nuanced take on the subject should consider attending the upcoming Industrial Methane Measurement conference. Due to take place in Rotterdam in the Netherlands on the 8th and 9^th June, the event is a fantastic opportunity for industry stakeholders, entrepreneurs and all other interested parties to find out more about methane from the experts.

What are the natural sources of methane?

As mentioned above, methane does have a variety of natural sources on the planet which have been around for millennia. In fact, an estimated 40% of the methane in our atmosphere is believed to be derived from naturally occurring emissions.

By far the biggest natural methane sources are the swamps, bogs and other wetlands which cover parts of the Earth’s land. With oxygen few and far between in such locations, it creates the perfect environment for methane-producing microbes that have evolved to handle such extreme conditions. The same is true for our seas and oceans, which host a plethora of these tiny microbes, as well as accumulating methane from sediments at their depths and from oil and gas fields which leach the gas slowly but continuously.

Other prominent natural sources include termites, which employ tiny micro-organisms in their gut to digest the cellulose they consume, resulting in the emission of methane as a by-product. Although the amount of methane produced by a single termite is negligible, they are believed to represent as much as 10% of all biomasses on the planet, adding up to one sizable methane bill. Meanwhile, the partial combustion of organic matter, such as occurs during wildfires, is another contributing factor.

What are the manmade sources of methane?

The remaining 60% of methane in our atmosphere is derived from manmade sources, which is why methane concentrations have risen sharply in the last 250 years. Here are a handful of the major culprits:

• Agriculture. For many people, the first thing they think of when they hear the word methane is the flatulence of farmyard animals, with cows, sheep and goats major sources of methane from both ends of the animal.
• Energy. Methane is the main component in natural gas, comprising around 85% of its makeup. When this and other fossil fuels like oil and coal are extracted, processed and combusted, some methane inevitably escapes into the atmosphere. Biofuels are another source, too.
• Petrochemicals. Since plastics are made from refined oil, methane is also generated throughout this industry, as well. From the initial extraction through the supply chain all the way to production, petrochemicals are an often-neglected source of methane by regulators.
• Landfill. Did you know that landfills are a breeding ground for the methane-producing microbes mentioned above? Compacted waste and organic matter leave little room for oxygen, allowing these bacteria to thrive. Landfills continue to expel methane long after closure.
• Wastewater. As well as material waste, human waste in the shape of faecal matter and urine is another primary source of methane. Both aerobic and anaerobic treatment systems are responsible for contributing methane into the surrounding environment.

While the above list is not an exhaustive one, it does cover the main sources of manmade methane emissions. Other contributing factors to the issue include rice paddies, stubble burning and land-clearing forest fires, as well as hydroelectric dams and technological devices.

How does methane contribute to climate change?

The number one reason why methane is now a gas which is carefully monitored in our environment is its impact on climate change. Behind carbon dioxide, methane is believed to be the biggest contributor to global warming, since it acts alongside other gases and contaminants as a blanket which traps the heat from the sun’s rays inside the troposphere, thus elevating the planet’s temperature.

Indeed, there is a school of thought which believes that methane is just as big a (if not an even bigger) concern than carbon dioxide due to its immense global warming potential. While it’s true that methane is around 200 times less concentrated in our atmosphere than CO2 and generally persists in the environment for just 12 years compared to the centuries or even millennia-long lifespan of carbon, it’s much more effective at retaining heat in that time.

In fact, it has been posited that methane is 28 times more powerful than carbon dioxide over a 100-year period, while it’s a whopping 80 times better at trapping heat over a 20-year timescale. As such, it’s no wonder that climate scientists and environmentalists are keen to clamp down on the emissions of this potent greenhouse gas.

Is methane harmful to human health?

Besides the obvious environmental concerns connected to methane, it also carries other dangers in high concentrations. For one thing, prolonged exposure to excessive levels of the gas can lead to methane poisoning which, despite the name, has more of an asphyxiating effect than a toxic one on the human body.

By starving the lungs of oxygen, methane poisoning can cause serious health complications. Minor symptoms of methane poisoning include shortness of breath, fatigue and dizziness, while it can also impair vision and induce memory loss. In the most extreme cases, it will bring on convulsions and can even kill. It’s detrimental to other life on the planet, too, with high concentrations of methane inhibiting plant growth and contributing to the creation of ground-level ozone.

Finally, methane is a highly flammable gas, but one which is also colourless and odourless. This means if a power plant, industrial site or other workplace does not prioritise detecting methane in its environment, the gas can be permitted to accumulate to unacceptable levels and present a significant fire risk.

What are the different methods of monitoring for methane?

Indeed, robust monitoring methods are important for ensuring the safety of all employees and visitors to a site, as well as complying with health and safety rules. Methane’s status as a powerful greenhouse gas also makes monitoring imperative for fulfilling national and international requirements, ensuring concentrations do not spiral out of control and measuring the progress of environmental measures.

While there are a wide variety of different methods of monitoring for methane, which are employed depending on the site in question, the source of the methane emissions and the preference of those in charge. However, the main techniques include:

• Satellite imaging. The use of advanced sensors fitted to orbital satellites is capable of monitoring methane emissions from space, which provides a comprehensive overview of the Earth’s surface and highlights major sources, such as forest fires or crop stubble burning.
• Stack sampling. By fitting a sensor or calibrated bag to the smokestack or other emission point of an industrial facility, its owners can capture a sample of the gases leaving the premises and use sophisticated laboratory techniques to analyse their composition for methane.
• Tracer gas dispersion. This method involves the controlled release of a tracer gas at the point of emission. Then, measurements of both the tracer gas and methane concentrations are taken further downwind from the site to obtain information about its behaviour and dispersal.
• Enclosure chamber measurement. By placing small chambers atop the emissions source, the concentration of methane can be recorded by monitoring fluctuations in methane levels over time (in static chambers) or comparing inflow and outflow rates (in dynamic chambers).
• Drone technology. By fitting drones with ultra-sensitive laser beams, site owners can access remote or difficult-to-reach parts of their facility and pinpoint the site of leakages or other issues. This is especially effective for lengthy sections of pipeline.

What are the uses of methane?

Fortunately, there are a variety of practical uses for methane which can help transform it from a damaging waste product into a useful and potentially lucrative commodity. By capturing methane at the point of emission and storing it for future use, two environmental birds can be killed with a single stone.

As the principal component of natural gas, the most logical and most commonplace use of methane is as a fuel source. This is true for both power stations, which serve to heat, light and power homes, businesses and other establishments around the world, and for modern vehicles which can be powered by alternatives to petrol or diesel. According to one estimate, driving a methane-powered car results in 20% fewer emissions than a conventional combustion engine.

Meanwhile, methane can also be processed into its constituent parts and converted into useful substances such as methanol, acetylene and hydrogen cyanide. Methanol is especially popular for use in the creation of such diverse consumer products as paint, adhesives, synthetic fibres and acrylic plastics.