Biogas: Overview, Topics, Production, Uses, & Facts

What is Biogas?

Biogas is a mixture of gasses made from raw materials such as agricultural waste, manure, municipal trash, plant material, sewage, green waste, and food waste. The main gasses in biogas are methane, carbon dioxide, and hydrogen sulfide. It is a renewable source of energy. Some basic points are discussed below:

• Biogas consist of methane and carbon dioxide with some traces of hydrogen sulfide for water (moisture) and also have siloxanes.

• So common raw materials which are used to produce biogas are agricultural waste manure, municipal trash plant materials, sewage green waste and food waste.

• Biogas is produced in anaerobic digesters.

• The formulation of biogas takes place through methanogenic and anaerobic respiratory organisms.

• It is utilized to fuel the heating process such as cooking or in harnessing the energy during combustion.

Biogas Plant

A biogas plant is a structure that offers anaerobic digestion conditions devoid of oxygen. Simply described, it's a man-made technology that allows garbage to be converted into environmentally friendly, biofertilizers and sustainable electricity. There are two types of biogas plants used for the production of biogas:

1. The fixed dome types of biogas plant

2. The floating has holder types of biogas plant

How is Biogas produced?

Biogas is produced in a biogas plant. A biogas plant is an anaerobic digester that treats biodegradable wastes including sewage, agricultural waste and food waste. During the process of anaerobic digestion, an air tight tank transforms biomass into methane. Biogas can be produced artificially or organically as part of industrial processes for fuel.

Environmental Impacts of Biogas

Using biogas as fuel has a positive impact on the environment. Its combustion produces no particulates, it contains no sulfur or heavy metals, and it is completely renewable, making it carbon-neutral. Some important impacts are discussed below;

• Biogas provides environmental sustainability as a fuel.

• The combustion of the biogas produces no particles and is free from sulphur or any kind of heavy metals.

• Biogas is a renewable source of energy which is also considered carbon neutral.

• The production of biogas reduces greenhouse emissions by 85 to 95% in the ecosystem.

• Utilization in biogas decreases the release of methane by 25 times as the potent CO2 particle.

• It also contributes to the ecological preservation of fossils.

Applications of Biogas

Biogas is a sustainable energy source with various uses across households, agriculture, and industries. It is an important alternative to conventional fuels. It helps in conservation of the environment. Some important applications of biogas are:

• To fuel cars, biogas can be compressed and used as a vehicle fuel.

• As a substitute for natural gas. If biogas is cleaned and upgraded to natural gas standards, it becomes biomethane and can be used similar to methane, including for cooking and heating.

• Used as a fuel by converting it into electricity through combustion and gas engines are fuel cells.

• Can be used for heating applications including space heating or hot water generation contributing to the energy efficiency of residential as well as industrial areas.

• The production of biogas from organic waste helps in efficient solid waste management which reduces the landfill areas.

Benefits of Biogas

Biogas has several advantages such as:

• It is a renewable source of energy and provides a good alternate energy source.

• It requires locally and easily available materials for production.

• It produces a clean fuel which helps in controlling air pollution.

• It also helps to control water pollution by decomposing sewage, animal dung and human excreta.

• It has a high calorific value.

• It burns readily and can be supplied through pipe lines.

Challenges of Biogas

Biogas is an environmentally friendly source of energy but it still has disadvantages, such as:

• It can be explosive when mixed in the ratio of one part biogas to 8-20 parts air.

• If it leaks, it smells like rotten eggs.

• The number of cattle owned by an average farmer is insufficient to feed a biogas plant.

• The initial cost of installation of the biogas plant is high.

• It cannot be easily stored.

Exam Relevance

During exam preparation, different types of questions about the Biogas are asked. The table below contains the different patterns of questions asked in different exams.

Biogas NEET MCQs

Q1. These bacteria grow anaerobically on cellulosic material , produce large amount of methane along with CO2 and H2, and are collectively called as methanogens . Example(s) of such bacteria are

1. Methanobacterium

2. Methanobrevibacter

3. Methanococcus

4. All of these

Correct answer: 4) All of these

Explanation:

Biogas is a renewable energy resource, mainly made up of methane, which comes from the anaerobic digestion process of microorganisms from organic matter. There are four steps in the process: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Biogas can be cooking and heating, electricity generation, or even vehicle fuel if purged. It offers the advantage of waste management and greenhouse gas reduction, among others, hence an alternative source of energy.

Hence the correct answer is Option 4) All of these.

Q2. Biogas is produced by

1. aerobic breakdown of biomass

2. anaerobic breakdown of biomass

3. with the help of methanogenic bacteria

4. both 2 and 3

Correct answer: 4) both 2 and 3

Explanation:

Microbes in the Production of Biogas - During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulfide and carbon dioxide. These gases form biogas and can be used as a source of energy as it is inflammable. The anaerobic bacteria involved in biogas production break down organic matter, such as plant and animal waste, in the absence of oxygen. Biogas, primarily composed of methane, can be harnessed for cooking, heating, and electricity generation, offering a renewable energy source.

Hence, the correct option is (4). Both 2 and 3

Q3. Identify the incorrect statement w.r.t. biogas plant

1. It consists of a concrete tank, 10-15 feet deep in which bio-wastes are collected and a slurry of dung is fed.

2. A floating cover is placed over the slurry, which keeps on rising as the gas is consumed in the tank.

3. It has an outlet, which is connected to a pipe to supply biogas to nearby houses.

4. The spent slurry is removed and may be used as fertiliser

Correct answer: 2) A floating cover is placed over the slurry, which keeps on rising as the gas is consumed in the tank

Explanation:

A normal biogas plant has a digester in which organic waste is broken down anaerobically to produce biogas. The inlet allows the entry of waste, while the outlet removes spent slurry, which can be used as fertilizer. A gas holder collects the produced biogas for cooking or electricity generation. Safety features ensure safe operation throughout the process.
Hence the correct answer is Option 2) A floating cover is placed over the slurry, which keeps on rising as the gas is consumed in the tank.

Also Read:

• MCQs on Microbes in Production of Biogas

• Animal Husbandry

• Antibiotics

FAQs on Biogas

Define biogas.

Biogas refers to a mixture of different gases produced by the breakdown of the organic matter in anaerobic conditions i.e., absence of oxygen. It is a renewable source of energy. The main source of raw material for production of biogas is plant and animal biomass. Biogas primarily consists of methane and carbon dioxide and have small amounts of hydrogen sulfide, hydrogen and nitrogen.

How is biogas produced?

Biogas is produced as landfill gas, which is produced by the breakdown of biodegradable waste inside a landfill due to chemical reactions and microbes. It is produced inside a digester which has anaerobic conditions.

What is the composition of biogas?

The main components of biogas are methane (CH4), typically 50-75% and carbon dioxide (CO2), typically 25-50%)=. It also contains small amounts of other gases like hydrogen sulfide (H2S), nitrogen (N2), and water vapor.

What are the uses of biogas?

• It is used as a cooking and heating fuel in rural and urban households

• Biogas can power gas lamps and electricity generators.

• The slurry left behind in the biogas plant is a nutrient-rich fertilizer for agriculture.

• It helps in waste management by reducing organic waste and lowering pollution.