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

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

Edited By Irshad Anwar | Updated on Jul 02, 2025 05:28 PM IST

Biogas is one of the renewable sources of energy which is produced from anaerobic digestion of organic materials. These materials are obtained from agriculture waste manure and food scraps which are easily found in residential areas. It comprises methane and carbon dioxide which is converted into alternative fuel which offers benefits to both the environment as well as economic health of the country. Biogas is one of the topics in Biology and they carry a weightage of 3% in NEET and 4% in CBSE and other Paramedical Exams.

This Story also Contains
  1. What is Biogas?
  2. Biogas Plant
  3. How is Biogas produced?
  4. Environmental Impacts of Biogas
  5. Applications of Biogas
  6. Types of Questions Asked from Biogas
  7. Tips, Tricks, and Strategies for Biogas

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 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 are also produced in anaerobic digesters and bio-reactors.

  • 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.

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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 fertilizers and sustainable electricity.

How is Biogas produced?

An eco-friendly, renewable energy source is biogas. It is created during a process known as anaerobic digestion, in which microbes break down organic matter, such as food or animal manure, without the presence of oxygen. The waste material must be contained in an environment with no oxygen for this to happen. 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 environment.

  • Utilise 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

Some important Applications of Biogas are discussed below:

  • 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 similarly to methane, including for cooking and heating.

  • Biogas is also 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 managing the waste efficiently which produces the landfill areas.

Types of Questions Asked from Biogas

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.

Exam Type

Types of Questions Asked

Weightage

CBSE

  • Definition and composition of biogas.

  • Processes involved in the production of biogas (anaerobic digestion).

  • Sources of organic material used for biogas production (agricultural waste, manure, etc.).

  • Environmental benefits of using biogas as a renewable energy source.

  • Applications of biogas in daily life (cooking, electricity generation).


4%

NEET

  • Chemical composition and energy content of biogas.

  • Role of microorganisms in biogas production (methanogens).

  • Comparison of biogas with other renewable energy sources (biomass, solar, wind).

  • Factors affecting biogas production (temperature, pH, substrate type).

  • Technological advancements in biogas production systems.


3%

Paramedical

  • Biogas as a waste management solution and its impact on sustainability.

  • Health benefits associated with using biogas over traditional fuels (reduction in indoor air pollution).

  • The role of biogas in reducing greenhouse gas emissions.

  • Economic advantages of biogas production for rural communities.

  • Challenges and limitations in the widespread adoption of biogas technology.

3%


Tips, Tricks, and Strategies for Biogas

It takes effort to remember everything in a single go. We made the entire problem easy. Some of the tricks regarding Biogas are given below which you can use to memorise the important points.

Biogas Production Process

"DAMP: Digestion, Anaerobic, Methanogens, Products"

  • D: Digestion (the breakdown of organic material by microorganisms)

  • A: Anaerobic (occurs in the absence of oxygen)

  • M: Methanogens (specific microorganisms that produce methane)

  • P: Products (mainly methane, carbon dioxide, and other trace gases)

Components of Biogas

"MCH: Methane, Carbon Dioxide, Hydrogen Sulfide"

  • M: Methane (CH₄) (the primary component and main energy source)

  • C: Carbon Dioxide (CO₂) (a byproduct, contributing to greenhouse gases)

  • H: Hydrogen Sulfide (H₂S) (present in small amounts, can be toxic)

Benefits of Biogas

"RICE: Renewable, Inexpensive, Carbon-neutral, Efficient"

  • R: Renewable (produced from organic waste materials)

  • I: Inexpensive (cost-effective compared to fossil fuels)

  • C: Carbon-neutral (helps reduce overall carbon emissions)

  • E: Efficient (provides a reliable source of energy for cooking, heating, and electricity)

Applications of Biogas

"HEAT: Heating, Electricity, Agriculture, Transport"

  • H: Heating (used for cooking and space heating)

  • E: Electricity (can be converted to electricity through generators)

  • A: Agriculture (used as organic fertilizer through digestate)

  • T: Transport (biomethane can be used as a vehicle fuel)

Challenges of Biogas

"NICE: Needs, Infrastructure, Contamination, Efficiency"

  • N: Needs (requires specific substrates for optimal production)

  • I: Infrastructure (needs proper setup for anaerobic digestion)

  • C: Contamination (risk of impurities affecting biogas quality)

  • E: Efficiency (requires optimal conditions for maximum gas production)

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Frequently Asked Questions (FAQs)

1. What is a biogas plant for home?

Biogas can be created locally, dependably, easily, and efficiently from organic waste such as food waste, market vegetable waste, animal manure, poultry litter, municipal sewage, press mud, bagasse, etc.

2. Is biogas harmful for humans?

The main dangers associated with biogas are explosion, asphyxiation, illness, and hydrogen sulphide poisoning.

3. What is the main disadvantage of Biogas?

The ineffectiveness of the techniques utilized to produce biogas today is a regrettable drawback of the fuel. There are currently no innovative solutions to streamline the procedure and make it affordable and accessible. This means it is still not feasible to produce on a sufficient scale to meet the needs of a huge population.

4. Does Biogas have a future?

Production of biogas and biomethane as a combined energy source reached 191 TWh in 2020, and by 2030, it is expected to triple. Production may increase by at least five times to over 1,000 TWh by 2050, and other projections put it as high as 1,700 TWh.

5. Are biogas plants profitable?

An entrepreneur who runs a dairy farm with between 50 and 60 animals may find selling biogas to be a lucrative business. The gas created by anaerobic digestion can be kept in small cylinders and utilized as fuel for cooking.

6. Can biogas be used as a transportation fuel?
Yes, biogas can be used as a transportation fuel. When purified and compressed, it becomes biomethane or renewable natural gas (RNG), which can power vehicles designed to run on compressed natural gas (CNG) or liquefied natural gas (LNG).
7. How is biogas purified for use?
Biogas is purified through a process called upgrading, which involves removing impurities like CO2, H2S, and water vapor. Common methods include water scrubbing, pressure swing adsorption, and membrane separation. The resulting purified gas, often called biomethane, has a higher methane content and can be used interchangeably with natural gas.
8. How does biogas contribute to the circular economy?
Biogas contributes to the circular economy by turning waste into valuable resources. Organic waste is converted into renewable energy (biogas) and nutrient-rich fertilizer (digestate). This closes the loop in waste management, reduces the need for synthetic fertilizers, and provides a sustainable energy source, exemplifying the principles of a circular economy.
9. How does biogas production help in waste management?
Biogas production helps in waste management by converting organic waste into useful energy and reducing the volume of waste that would otherwise end up in landfills. This process not only generates renewable energy but also produces a nutrient-rich byproduct (digestate) that can be used as fertilizer.
10. What are the challenges in scaling up biogas production?
Challenges in scaling up biogas production include: ensuring a consistent supply of suitable feedstock, managing the high initial investment costs, addressing technical issues in large-scale digesters, dealing with variations in biogas quality and quantity, and developing infrastructure for biogas distribution and use.
11. What are the main differences between small-scale and large-scale biogas production?
Small-scale and large-scale biogas production differ in several aspects:
12. What safety considerations are important in biogas production and use?
Important safety considerations in biogas production and use include: preventing gas leaks (as methane is flammable and can create explosive mixtures with air), managing the risk of hydrogen sulfide toxicity, ensuring proper ventilation in enclosed spaces, maintaining equipment to prevent failures, and training personnel in safe operating procedures. Proper design and regular maintenance of biogas systems are crucial for safety.
13. How does the energy return on investment (EROI) of biogas compare to other energy sources?
The energy return on investment (EROI) for biogas varies depending on the feedstock and production system but is generally lower than that of fossil fuels and some other renewables. However, biogas EROI can be competitive when considering the energy saved from waste management and the use of waste heat from biogas plants. The EROI of biogas is typically higher than that of some biofuels like corn ethanol. It's important to consider that biogas provides additional benefits beyond just energy production when evaluating its overall value.
14. What is the concept of "biogas upgrading" and why is it important?
Biogas upgrading refers to the process of purifying raw biogas to increase its methane content, typically to over 95%. This is important because:
15. How does the microbial community in a biogas digester change over time?
The microbial community in a biogas digester is dynamic and changes over time. Initially, the community is dominated by hydrolytic and acidogenic bacteria. As the process continues, acetogenic bacteria and methanogens become more prevalent. The community composition can also shift in response to changes in feedstock, temperature, or other operational parameters. Understanding these changes is crucial for optimizing biogas production and maintaining digester stability.
16. What are the environmental benefits of using biogas?
Using biogas offers several environmental benefits: it reduces greenhouse gas emissions by capturing methane that would otherwise be released into the atmosphere, it helps manage organic waste, reduces reliance on fossil fuels, and produces a nutrient-rich fertilizer as a byproduct.
17. Why is biogas considered a renewable energy source?
Biogas is renewable because it's produced from organic materials that can be replenished naturally within a human timescale. Unlike fossil fuels, which take millions of years to form, the organic matter used for biogas can be continuously generated through agricultural practices, waste management, and natural processes.
18. How does biogas production affect soil health when digestate is used as fertilizer?
When digestate from biogas production is used as fertilizer, it can positively affect soil health. The digestate is rich in nutrients like nitrogen, phosphorus, and potassium, which are readily available to plants. It also adds organic matter to the soil, improving soil structure, water retention capacity, and microbial activity. However, proper application rates and timing are crucial to avoid potential negative impacts like nutrient runoff.
19. How does biogas production compare to other forms of renewable energy in terms of efficiency?
Biogas production efficiency varies depending on the feedstock and production system. While it may not be as efficient as some other renewables in terms of energy output per unit area (like solar or wind), biogas has the advantage of providing continuous power and utilizing waste materials. Its overall efficiency should be considered in the context of its waste management benefits and potential for heat recovery.
20. What is the global potential for biogas production?
The global potential for biogas production is significant but largely untapped. According to the International Energy Agency, the technical potential of biogas could cover around 20% of global gas demand. However, current production is far below this potential, leaving room for substantial growth, especially in developing countries with large agricultural sectors.
21. What is biogas and how is it produced?
Biogas is a renewable energy source produced through the anaerobic digestion of organic matter like animal manure, food waste, or plant material. Microorganisms break down this matter in the absence of oxygen, producing a mixture of gases primarily composed of methane and carbon dioxide.
22. What is a biogas digester?
A biogas digester is a sealed container or system where anaerobic digestion takes place. It provides an oxygen-free environment for microorganisms to break down organic matter and produce biogas. Digesters can range from small household units to large industrial-scale systems.
23. What is the role of microorganisms in biogas production?
Microorganisms play a crucial role in biogas production. Different groups of bacteria work together in a series of stages: hydrolysis (breaking down complex organic compounds), acidogenesis (converting simpler compounds into organic acids), acetogenesis (producing acetate), and methanogenesis (producing methane). Each group of microorganisms is specialized for its specific role in the process.
24. How does the composition of feedstock affect biogas production?
The composition of feedstock significantly affects biogas production. Feedstocks with higher amounts of easily degradable organic matter (like fats and carbohydrates) generally produce more biogas. The carbon-to-nitrogen (C/N) ratio of the feedstock also impacts production efficiency, with an optimal range typically between 20:1 and 30:1.
25. How does temperature affect biogas production?
Temperature significantly affects biogas production as it influences the activity of the microorganisms responsible for anaerobic digestion. Optimal biogas production occurs in two temperature ranges: mesophilic (30-38°C) and thermophilic (50-60°C). Higher temperatures generally lead to faster decomposition and more biogas production, but require more energy to maintain.
26. What are the main components 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.
27. What is the difference between biogas and natural gas?
While both biogas and natural gas contain methane as their primary component, they differ in origin and composition. Biogas is produced from organic matter through anaerobic digestion, while natural gas is a fossil fuel formed over millions of years. Biogas typically contains more CO2 and other impurities compared to natural gas.
28. How does the energy content of biogas compare to that of fossil fuels?
The energy content of biogas is lower than that of fossil fuels like natural gas or petroleum. Raw biogas typically has an energy content of about 20-25 MJ/m³, while natural gas has about 35-40 MJ/m³. However, when biogas is upgraded to biomethane, its energy content becomes comparable to that of natural gas. Despite the lower energy density, biogas's renewable nature and waste management benefits make it a valuable energy source.
29. What is the role of biogas in achieving carbon neutrality?
Biogas plays a significant role in achieving carbon neutrality by providing a renewable alternative to fossil fuels and reducing methane emissions from organic waste decomposition. When biogas replaces fossil fuels, it creates a closed carbon cycle where the CO2 released during combustion is offset by the CO2 absorbed by the organic matter during its growth. Additionally, capturing methane that would otherwise be released into the atmosphere helps mitigate a potent greenhouse gas.
30. What is co-digestion in biogas production?
Co-digestion is the simultaneous anaerobic digestion of two or more types of organic substrates. This process can improve biogas yield by balancing nutrient content, improving the C/N ratio, and increasing biodegradability. For example, combining animal manure with food waste often results in higher biogas production than digesting either substrate alone.
31. How does biogas production impact water resources?
Biogas production can have both positive and negative impacts on water resources. On the positive side, it can treat wastewater and reduce water pollution from organic waste. The process also produces liquid digestate that can be used for irrigation. However, large-scale biogas plants may require significant water inputs for dilution and cleaning. Proper water management practices are essential to minimize negative impacts and ensure sustainable biogas production.
32. What is the difference between dry and wet anaerobic digestion in biogas production?
Dry and wet anaerobic digestion differ in the moisture content of the feedstock. Wet digestion typically handles feedstock with less than 15% dry matter content, while dry digestion processes material with 20-40% dry matter. Wet systems are more common and suitable for liquid wastes like sewage or animal slurries. Dry systems are often used for solid wastes like crop residues or municipal solid waste. Each system has its advantages in terms of efficiency, water usage, and types of feedstock that can be processed.
33. How does biogas production affect local ecosystems?
Biogas production can affect local ecosystems in several ways. Positively, it can reduce pollution from untreated organic waste and decrease greenhouse gas emissions. The use of digestate as fertilizer can improve soil quality and reduce reliance on synthetic fertilizers. However, potential negative impacts include odor issues, the risk of nutrient runoff if digestate is improperly applied, and changes in land use if energy crops are grown specifically for biogas production. Proper management and regulations are crucial to maximize benefits and minimize negative impacts.
34. What is the role of government policies in promoting biogas adoption?
Government policies play a crucial role in promoting biogas adoption. These can include financial incentives like subsidies or tax breaks for biogas projects, renewable energy mandates that include biogas, regulations on waste management that favor anaerobic digestion, and support for research and development in biogas technologies. Policies can also address barriers to biogas adoption, such as grid connection issues or permitting processes. Effective policies consider the multiple benefits of biogas, including renewable energy production, waste management, and rural development.
35. What are the potential uses of biogas beyond electricity generation?
Beyond electricity generation, biogas has several potential uses:
36. What is the concept of "power-to-gas" and how does it relate to biogas?
"Power-to-gas" is a technology that converts excess electrical energy into gas fuel. In relation to biogas, this concept can be applied by using surplus renewable electricity (e.g., from wind or solar) to produce hydrogen through electrolysis. This hydrogen can then be combined with CO2 from biogas to produce methane through a process called methanation. This approach can increase methane yield from biogas plants and provide a means of storing excess renewable energy in the form of gas.
37. How does biogas production contribute to rural development?
Biogas production contributes to rural development in several ways:
38. How does the pH level affect biogas production?
pH level significantly affects biogas production as it influences the activity of microorganisms involved in anaerobic digestion. The optimal pH range for biogas production is typically between 6.8 and 7.2. If the pH drops too low (becomes too acidic), it can inhibit methane-producing bacteria and lead to a buildup of volatile fatty acids, potentially causing digester failure. Conversely, if the pH becomes too high (too alkaline), it can also inhibit microbial activity. Maintaining the proper pH balance is crucial for efficient and stable biogas production.
39. What is the role of trace elements in biogas production?
Trace elements play a crucial role in biogas production by serving as cofactors for enzymes used by microorganisms in anaerobic digestion. Elements like iron, nickel, cobalt, molybdenum, selenium, and tungsten are essential for optimal microbial growth and activity, particularly for methanogens. A deficiency in these trace elements can lead to reduced biogas production or even process failure. The need for trace element supplementation depends on the feedstock composition and can be particularly important in mono-digestion systems.
40. How does biogas production impact greenhouse gas emissions from agriculture?
Biogas production can significantly reduce greenhouse gas emissions from agriculture in several ways:
41. How does seasonal variation affect biogas production?
Seasonal variation can significantly affect biogas production:
42. What is the potential of using algae for biogas production?
Algae have significant potential for biogas production:

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Question : Sentences of a paragraph are given below. While the first and the last sentences ( 1 and 6) are in the correct order, the sentences in between are jumbled up (A to D). Arrange the sentences in the correct order to form a meaningful and coherent paragraph.

1. Biogas is a mixture of methane, carbon dioxide and hydrogen with others.
A. Biogas is produced by anaerobic degradation of animal wastes (some plant wastes) in presence of water.
B. Thus, biogas is a non-polluting, cleaned and low cost fuel.
C. Anaerobic degradation means breakdown of organic matter which is done in the absence of oxygen.
D. It is mostly used in rural areas where ample animal and agricultural waste is available.
6. Biogas eliminates the risk of health hazards offered by other fuels.

Option 1: DABC

Option 2: CBDA

Option 3: ACBD

Option 4: BDAC

Correct Answer: ACBD


Solution : The correct choice is the third option.

The initial sentence (A) introduces the concept of biogas as a mixture of methane, carbon dioxide, and hydrogen. The subsequent sentence (C) explains the process of biogas production through anaerobic degradation, clarifying that it occurs in the absence of oxygen. The third sentence (B) follows by highlighting the positive aspects of biogas, stating that it is a non-polluting, clean, and low-cost fuel. Finally, the last sentence (D) concludes the paragraph by noting that biogas is primarily used in rural areas where ample animal and agricultural waste is available, eliminating the risk of health hazards associated with other fuels.

Therefore, the correct answer is ACBD.

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Question : Assertion: Diversification of agricultural activities promotes the use of renewable energy.

Reason: It encourages the adoption of technologies like solar pumps and biogas plants for irrigation and energy needs.

Option 1: Both assertion and reason are true, and the reason is the correct explanation of the assertion.
 

Option 2: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
  

Option 3: Assertion is true, but the reason is false.

    

Option 4: Assertion is false, but the reason is true.

Correct Answer: Both assertion and reason are true, and the reason is the correct explanation of the assertion.
 


Solution : The correct answer is (a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.

Diversification of agricultural activities does promote the use of renewable energy, and the reason for this is that it encourages the adoption of technologies like solar pumps and biogas plants for irrigation and energy needs.

Diversification of agricultural activities refers to the practice of engaging in multiple types of agricultural production or incorporating non-traditional activities alongside traditional farming. This can include activities such as horticulture, livestock rearing, agroforestry, and aquaculture.

Solar pumps utilize solar energy to power water pumps for irrigation purposes, reducing reliance on conventional electricity or fossil fuel-powered pumps. This helps in conserving energy and reducing greenhouse gas emissions. Biogas plants utilize organic waste, such as animal manure and crop residues, to produce biogas through anaerobic digestion. The biogas can be used for cooking, heating, and generating electricity on the farm, providing a renewable and sustainable source of energy.

By diversifying their agricultural activities, farmers can generate the organic waste needed for biogas production and create a self-sustaining energy system. This promotes the use of renewable energy and contributes to reducing the dependence on non-renewable energy sources.

Therefore, the assertion that diversification of agricultural activities promotes the use of renewable energy is true, and the reason that it encourages the adoption of technologies like solar pumps and biogas plants for irrigation and energy needs is the correct explanation for this assertion.

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Team Careers360 20 January,2024

Question : Which gas is the major component of biogas?

Option 1: Compressed natural gas

Option 2: Methane

Option 3: Hydrogen

Option 4: Liquefied petroleum gas

Correct Answer: Methane


Solution : The correct option is Methane.

The chemical formula of methane is CH4. This gas is colourless, odourless, and flammable. It is used for heating, cooking, and electricity generation. Excessive methane emissions contribute to global warming.

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Team Careers360 21 January,2024
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