Methane (CH4) is a colorless, odorless gas commonly used as a fuel – the main component of natural gas. It is a hydrocarbon and, therefore, organic in nature. It is also one of the carbon originating gases that play a major role in the greenhouse effect. As claimed by the U.S. Environmental Protection Agency (EPA), 10 percent of greenhouse gas emissions is from the use of methane gas. The gas is lighter than air and can only be in gaseous form.
It is a form of fossil fuel that is naturally occurring below the earth’s surface as an end product of anaerobic decomposition by methanogens, where it is found together with other fossils fuels such as coal and oil. Methane gas can also be produced in a laboratory by heating a mixture of sodium ethanoate and soda-lime.
Due to its hydrocarbon quality and quantity, it is a very flammable gas. It burns readily in the air with a pale non-luminous flame by reacting with oxygen to give off carbon dioxide, water vapor, and a lot of heat. This article seeks to highlight the sources, uses and effects of Methane gas.
Sources of Methane Gas
1. Fossil fuels
Fossil fuel is by far the greatest source of energy in the world – used to drive engines in cars, turbines and other machinery. Fossil fuels is extracted from decayed organic matter that has decomposed over millions of years under intense heat leading to the disintegration of matter to fuel.
As a result, it is mainly made up of carbon, a major source of methane gas. Methane gas is naturally occurring below the earth’s surface, and since it is in gaseous form, it is not easy to trap or extract. It is generated from the other hydrocarbons in liquid and solid-state such as oil and coal, respectively.
Artificial wetlands such as dams and ponds may influence the presence of methane gas. About 30% of methane emissions are produced by wetlands, including ponds, lakes and rivers. It is common to find that such areas were cleared of vegetation to reclaim it for construction. After, the dead organic matter continues to decompose at the base of these structures leading to the production of methane gas in water.
The presence of water and lack of fresh open air fastens the process of rotting of the dead organic matter. This decomposition process is what leads to the generation of methane gas at the bottom of the wetland. Naturally occurring wetlands have the same effect.
Termites are a significant natural source of methane. Each termite produces small amounts of methane on a daily basis. But when it gets multiplied by the world population of termites, their emissions add up, creating a total of 23 million tonnes of methane per year.
During the normal digestion process of a termite, methane gets produced. Termites eat cellulose but rely on microorganisms in their gut to digest it. These microorganisms produce methane during the process, which is 12% of natural methane emissions.
Another significant natural source of methane is oceans. Methane-producing microbes living in the ocean create these emissions. This creates 10% of natural methane emissions. Globally, oceans create 19 million tonnes of methane per year.
Oceanic methane emissions often get produced in deeper sediment layers of productive coastal areas. This accounts for 75% of the ocean’s methane emissions. The methane created by these microbes mixes with the surrounding water. After some time, it gets emitted to the atmosphere from the ocean surface.
One of the most recommended modes of waste disposal is composing, especially for organic waste. Composting involves the layering of different types of organic matter to recycle the waste back to the earth in a safe and friendly way.
Consequently, the mixture of dead organic matter leads to the production of methane gas to the atmosphere. However, composting releases small amounts of the gas in comparison to other sources of gas and is hence not a hazard.
6. Livestock farming
Livestock farming creates 90 million tonnes of methane per year.As humans raise ruminant animals like cows, sheep and goats for food, the enteric fermentation in these farm animals creates 27% of human methane emissions.
During their normal digestion process, they create large amounts of methane. Enteric fermentation occurs because of microorganisms in the stomach of these animals. This creates methane as a by-product that is either exhaled by the animal or released via flatus. This is why the meat that we eat every day has a huge impact on total methane emissions.
7. Animal waste
In a bid to save on non-renewable sources of energy, the globe has encouraged livestock production systems to take up the practice of producing biogas to provide cheap and affordable energy. Livestock production has led to the growth of this renewable energy source since it provides all the materials necessary for the setting up of the plant. This has seen more release of methane into the atmosphere through the fermentation of animal waste.
8. Anaerobic decomposition
Methane gas is produced when there is anaerobic bacterial decomposition. This means that the process of decomposition of organic matter does not require oxygen; rather, it requires suitable media for the bacteria to thrive. It often occurs during the decomposition of organic waste in landfills, the decay of organic material in wastewater from domestic, municipal and industrial sources and while managing large amounts of manure by using large waste treatment systems and holding tanks in livestock farming.
9. Waste management
Sewage raw wastewater is treated for it to be deemed safe for release back into the waterways. During treatment, sludge is left behind as residue, and since the sludge is often a mixture of compounds especially organic matter, suitable bacteria make this their home and help in decomposition leading to the production of methane gas.
10. Coal mining
Coal is the densest form of fossil fuel extracted from the earth’s surface, and because of this, it is solid in state and occupies a lot of space, thereby trapping methane gas below. Mining of coal leads to freeing of methane gas into the atmosphere as it is not easily trapped.
11. Rice fields
For rice to grow, it is grown in padded fields, which are flooded with water. Too much water depletes the oxygen present in the soil and also leads to the decomposition of organic materials present, which provides a suitable media for the production of methane gas. The gas is released through diffusion into the atmosphere. Paddy rice fields are among the biggest sources of methane gas released into the environment.
12. Burning of wood fuel
The use of firewood and charcoal is common because it is a cheap way of generating cooking and heating energy. Yet, whenever wood fuel is used, it releases methane gas into the atmosphere. Forest fires also release the gas into the atmosphere.
13. Biomass burning
Biomass is material from living or dead organic matter. Biomass burning causes a large amount of methane emissions. Large scale open fires by humans to destroy crop waste and clear land for agricultural or other uses creates 11% of human methane emissions. Natural wildfires can contribute to this. But the great majority of biomass burning gets caused by human beings. Biomass burning creates 38 million tonnes of methane per year.
Biofuels produce 12 million tonnes of methane each year. Any biomass used to produce energy for domestic or purposes counts as a biofuel. An estimated 80% of biofuels are used for domestic cooking, heating, and lighting by burning wood, agricultural waste, or animal dung. This is the single largest contributor to global biofuel emissions.
About 2.7 billion people, almost half of the world’s population, use solid biofuels for cooking and heating their homes on a daily basis. Most are poor and live in developing countries. The other sources of biofuels are low technology enterprises such as brick or tile making kilns, restaurants, transportation vehicles etc.
15. Landfills and waste
Landfills and waste produce 55 million tonnes of methane per year. Landfills and open garbage dumps are full of organic matter like food scraps, newspapers, cut grass and leaves. As we keep on dumping new garbage over the old garbage, the organic matter in our garbage gets trapped in conditions where there is no oxygen. This provides excellent conditions for methane-producing microbes to break down the waste, producing large amounts of methane emissions. Even after a landfill gets closed, bacteria will continue to decompose the buried waste and keep emitting methane for years.
Uses of Methane Gas
1. Used in cooking
Methane is a hydrocarbon and lighter than air. Therefore, it produces more energy per unit weight in comparison to oil and coal. It is also preferred for cooking since it does not have any smell and does not leave soot on the cooking utensils.
2. Residential Uses
Other uses of methane are to heat and cool their homes. Some homes use methane natural gas to heat their water. Another common use in the home is a natural gas fireplace. There are also natural gas dryers for clothes, but not very common.
3. Used to provide lighting
Methane gas can be harnessed to generate electricity for homes as well as offices and industries. Through a process called distributed generation, the methane in natural gas can create electricity. Microturbines (heat engines) and natural gas fuel cells can produce enough electrical energy.
4. Used in production of other compounds
Methane gas is essential for the formation of methanol (methyl alcohol), which is a key component of alcohol. It is also important in the artificial manufacture of hydrogen to be used in various industries.
Hydrochloric acid, one of the most common acids used in laboratories, is manufactured with methane gas as an ingredient. Trichloromethane is another compound that requires methane gas. Also known as chloroform, it is used extensively both as a solvent and an anesthetic.
5. Used to run industrial machinery
Methane, as the form of natural gas, is important for a variety of industries. It is a common fabric, plastic, anti-freeze and fertilizer ingredient. Methane gas is used to run or power engines and turbines in factories. Industries like pulp and paper, food processors, petroleum refineries and companies that work with stone, clay and glass, use the energy it releases. Methane-based combustion helps businesses dry, dehumidify, melt and sanitize their products. It is also used to provide energy for lighting purposes.
6. Used to produce carbon black
Methane gas can be burned incompletely, leading to unusual carbon deposits. These deposits are known as carbon black and are used to strengthen rubber which is used to make vehicle tires. This same carbon black is used to make paints and printing ink.
7. It is a fertilizer ingredient
With the addition of hydrogen, methane gas is used to manufacture ammonia, which is a key compound in the manufacture of fertilizers.
8. Used as rocket fuel
Its gaseous state translates to less carbon deposits when combusted, making it ideal for rocket fuel. It also leaves no residue. Other forms of fuel, such as kerosene, emit a lot of carbon, making the rocket combustion chamber faulty.
Effects of Methane Gas on Our Environment
A mixture of methane and air is very explosive in nature. About 20% of air is oxygen, and it becomes very reactive when it comes in contact with methane. There have been cases of explosions, especially in coal mines, where the mines collapse merely due to the reaction between the methane gas in the mine and the oxygen in the air.
Explosions have also been witnessed in landfills where organic waste had been compacted, and methane gas is being released in large amounts. Spontaneous reaction with the air around the landfill that may lead to an outbreak of fire has been reported.
2. Greenhouse effect
On its own, methane gas is of no harm to the environment or to life. Nonetheless, in increased concentration of the gas coupled up with the presence of carbon dioxide and water vapor, there is massive absorption and trapping of heat in the atmosphere that is harmful to the environment. The result is termed as the greenhouse gas effect associated with climate change and global warming.
In its extremely cold form, methane gas can cause burns whenever it gets into contact with the skin and eyes.
In high concentrations and enclosed space, the gas can react with all the oxygen present and rid the area of all oxygen leading to suffocation.
Engines emit hydrocarbons and fumes due to the combustion of methane gas, which can be hazardous once inhaled in the body. On the other hand, exposure to high levels of methane can lead to headaches, vomiting, nausea and loss of consciousness.
6. Climate Change
After carbon dioxide, methane is responsible for about 23% of climate change in the twentieth century as per NASA. Methane that is released into the atmosphere before it is burned is harmful to the environment. Compared to other greenhouse gases, methane’s lifespan in the atmosphere is relatively short, but it is more efficient at trapping heat than are those other gases. As it is able to trap heat in the atmosphere, methane contributes to climate change.