Bio Gas

Biogas: The Perfect Fuel For A Greener Tomorrow And Cleaner Environment

As fossil fuels are going scanty, the need to use bio-fuel is growing rapidly. Many sectors and industries are slowly turning towards bio-fuel. As the name suggests, bio-fuel is derived from biological sources. One such biofuel that was discovered a long time back around the 18th century is; biogas. This gas ever since has been used as a form of energy and to decompose the waste-organic materials. In some place, the production takes place on a large scale, while they are smaller scale in another place. The basic requirements of products include organic waste and a plant, where the waste undergoes anaerobic decomposition to produce methane. Let’s delve deeper into knowing what this biofuel is all about and how it is useful.

What is biogas?

This gas is a natural and environmentally friendly energy source in the form of methane and other gases. Biogas is mostly composed of methane produced during the anaerobic digestion of organic wastes. Methane concentration is usually around 50-75%, and the rest goes to other gases like carbon dioxide. Waste material used can be anything from sewage waste to farm waste to household organic waste. The feedstock material is broken down in the absence of oxygen in digesters to produce the gas. This gas is then used as an energy source to light up the streets, cool, heating, etc.    

Methane is a highly flammable gas, and it gives a bright blue flame. However, it is still safer than methane gas produced in landfills, causing accidents and hazards. Biogas is not only a renewable gas that is stopping the wastage of fossil fuels across the globe. It is also helpful in reducing the global waste epidemic. The waste, when littered and dumped, produces methane as well, thus polluting the environment multifold. Methane also traps the heat from the carbon dioxide, thus, making the gasless dangerous.

Feedstock for production

The feedstock is the material and wastes that are used in the biofuel digester plants. The feedstock used in the plants comprises all organic waste types that come from homes, farms, and industries. Some of the common feedstock materials for biogas production are:

  • Animal wastes: There are varying types of animal wastes used like livestock manure, mortality from farms, slaughterhouse wastes, etc.
  • Farm wastes: Organic agricultural and farm wastes include waste feed, corn silage, harvest waste, etc.
  • Food scraps: Food scraps comes from homes and other food serving places, which includes fresh produce wastes, cafeteria wastes, etc.
  • Industrial wastes: Many industries also produce organic wastes like food processing wastes, milk-house wash water, ethanol stillage, sewage sludge, etc. 

Types of biogas digesters

For the proper production of this fuel, it is very crucial to have the right digester. From the volume to height to shape, everything needs to be taken into consideration. The digesters can be either large scale or small scale, which also tends to decide which types of digesters are used. 

Small scale digesters

The small scale digesters are simplistic in design and are mostly used for villages, small towns, and housing projects. Some of the popular digester types of small scale production of biogas are:

  • Floating drums: In this, a floating gas tank is situated on top of the digester tank. It floats on the slurry to the water jacket.
  • Fixed dome: In this, the digester is of the dome shape and, the gas tank is fixed, along with a displacement pit.
  • Balloon digesters: In this, the digester is a heat-sealed balloon made of rubber, consisting of both gas holders and digester.
  • Polyethylene tube digester: This is a low-cost digester with polyethylene films bent at both ends around a drainpipe made of PVC.
  • Earth pit digester: These digesters are made by making a pit in the soil with a gas tank made of metal or plastic sheet.
  • Ferro cement digester: In this biogas digester is cement either standing alone or in the earth pit. 

Large scale digesters

The large scale digesters are ones which, used for large amounts of fuel production. Most of the time, these digesters run for industrial purposes only. Some of these digesters are:

  • Batch plants: In this, the feedstock is added together in a single batch and, then the process takes place over some time.
  • Continuous plants: The digester is fed with feedstock continuously and the digested after the product is also removed continuously.

Biogas production - the steps

In nature, this biofuel production happens almost every day. The organic materials are decomposed with the help of enzymes and bacteria in heat and pressure. In turn, the process releases gases like carbon dioxide and methane. The same principle is used in industrial production as well. The only difference is that the production takes place on a large scale and in a controlled environment. The process of biogas production is both physical and biochemical. 

The physical process of production

The physical process is what industries plants set up to enhance the process’s speed and effectiveness. The technological steps included are:

  • Crushing: The feedstock is crushed and pulped using the crusher to break down the bio-waste into smaller and easy to digest pieces.  
  • Slurrifying: In this step, water and liquid are added to make a slurry of the bio-waste in the digester tanks, making it easier to decompose. 
  • Heating: The bio-waste slurry is then heated up to 37 degrees Celsius, as warmness is required for the bacteria to act on the slurry.
  • Anaerobic digestion: In this process, the bio-waste is digested with anaerobic bacteria and enzymes to produce biogas.
  • Purification: This is the last stage, where the fuel produced is purified by removing the carbon dioxide and other impurities.

Biochemical process

The biochemical process takes place in the anaerobic digestion step of production by methane and acidic bacteria. The steps involved in this anaerobic digestion are:

  • Hydrolysis: In these long-chain complex carbohydrates, lipids and proteins in the waste are broken down by the bacteria’s enzymes.
  • Fermentation: In these step acidic bacteria, convert simpler molecular to organic substances used by methane bacteria to produce methane.
  • Methane formation: In the last stage, methane bacteria use the organic products of fermentation like acetic acid, hydrogen, carbon dioxide, etc., to produce methane.

Applications of biogas

Biogas is slowly gaining a lot of traction because of the continuous depletion of fossil fuels and wasting non-renewable energy sources. Today, this biofuel is used in many places and sectors to elevate the eco-friendly lifestyle and reduce cost.

Some of the main applications of the gas that the world have seen in the last few years are: 

  • Electricity: It is used to generate electricity at much cheaper pricing than hydroelectric plants and solar panels.
  • Cooking: It helps run stovetops which run by fuel, and is especially useful in remote areas and developing countries.
  • Automobiles: Biogas, when purified and compressed, can act as natural gas and, thus, can be used to power vehicles.
  • Generators: The portable generators can be run using this fuel instead of natural or propane gas. 
  • Income: In many countries under the Kyoto agreement, using green gas helps obtain benefits and income.
  • Heating and cooling: Several central heating and cooling systems use fuel cells, which uses biofuel as its electricity source.

Pros of biogas

Many reasons make this fuel a great alternative against those fossil fuel-based gas and sources of energy. Some of the benefits of biogas are:

  • Reduce pollution: Using up the organic waste materials helps remove pollutants, making the soil and water dirty.
  • Eco-friendly: The biogas does not use up non-renewable resources; instead, it uses the waste produced, thus, focusing on sustainable development.
  • Organic fertilizer: The production of this fuel has a byproduct that can be used as organic fertilizers on the farm instead of chemical fertilizers.
  • Low-cost tech: The biogas production process is low cost and requires less energy consumption, making it a greener and cheaper fuel source. 
  • Developing areas: This gas can be produced in those areas which are still developing and remote, thus helping in better development and growth.

Cons of biogas

Other than some great benefits of this biofuel form, some things still can be counted as disadvantages. Some of the cons of this fuel are:

  • Temperature effect: The production requires a particular temperature in which the bacteria can function, making the process weather dependant.
  •  Impurities: In this gas, several impurities may not get removed even after the purification process.
  • Not so efficient: The effectiveness of the technologies used in the production is still not that advanced, thus creating a setback.

When it comes to sustainable development and cleaner energy sources, one can find many alternatives these days. Biogas is one of the oldest forms of eco-friendly fuel used in various things in daily life activities. This fuel helps to acquire a cleaner environment and helps grow and advance the developing areas and regions. It is an economical, sustainable, and the best way to cater to all human needs without being selfish. With the spread of information about biogas, and people accepting and blending it in their lives, the world is sure to become a good place to live in.

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