Biogas: Overview, Topics, Production, Uses, & Facts
Biogas is a renewable source of energy produced by anaerobic digestion of organic materials such as agricultural waste, animal manure, and food scraps. This process is carried out by microorganisms in the absence of oxygen, leading to the formation of a gaseous mixture primarily composed of methane and carbon dioxide. It serves as an eco-friendly alternative to fossil fuels. This aligns with the concept of microbes in human welfare, where beneficial microorganisms contribute significantly in making a sustainable environment.
This Story also Contains
- What is Biogas?
- Biogas Plant
- How is Biogas produced?
- Environmental Impacts of Biogas
- Applications of Biogas
- Types of Questions Asked from Biogas
- Tips, Tricks, and Strategies for Biogas
- MCQs on Biogas
- Frequently Asked Questions (FAQs)
The production of biogas plays a crucial role in promoting clean energy and reducing environmental pollution. As a form of biofuel, biogas can be used for cooking, electricity generation, and even as fuel for vehicles. It also supports sustainable agricultural practices by utilizing farm waste effectively, thereby improving rural sanitation and promoting circular economy in farming communities.
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 are also produced in anaerobic digesters and bioreactors.
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.
Commonly Asked Questions
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.
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.
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.
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.
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.
Commonly Asked Questions
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.
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.
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.
How is Biogas produced?
An eco-friendly, renewable energy source is biogas. It is created during a process known as anaerobic digestion or fermentation. In this process microbes break down organic matter, such as food or animal manure in absence of oxygen. The waste material must be kept in an environment with no oxygen. Biogas can be produced artificially or organically as part of industrial processes for fuel.
Commonly Asked Questions
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.
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.
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.
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.
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.
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.
Commonly Asked Questions
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.
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.
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.
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.
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.
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.
Commonly Asked Questions
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).
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.
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.
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.
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.
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 |
| 4% | |
| 3% | |
Paramedical |
| 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)
MCQs on Biogas
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
Methanobacterium
Methanobrevibacter
Methanococcus
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
aerobic breakdown of biomass
anaerobic breakdown of biomass
with the help of methanogenic bacteria
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
It consists of a concrete tank, 10-15 feet deep in which bio-wastes are collected and a slurry of dung is fed.
A floating cover is placed over the slurry, which keeps on rising as the gas is consumed in the tank.
It has an outlet, which is connected to a pipe to supply biogas to nearby houses.
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:
Frequently Asked Questions (FAQs)
Q1. What is biogas?
Biogas is a renewable fuel produced by the breakdown of organic matter such as animal waste or plant material in the absence of oxygen (anaerobic digestion). It mainly contains methane (CH₄) and carbon dioxide (CO₂).
Q2. What are three uses of biogas?
Biogas is used for cooking, generating electricity, and as a fuel for vehicles. It is an eco-friendly alternative to conventional fossil fuels.
Q3. What is the biogas chemical formula?
Biogas doesn't have a fixed chemical formula, but its main component is methane (CH₄), typically making up about 50–70% of the mixture.
Q4. Why is biogas called fuel?
Biogas is called fuel because it can be burned to produce heat or electricity, making it a useful source of energy for various domestic and industrial applications.
Q5. Who invented biogas?
The first documented use of biogas was by Alessandro Volta in the 18th century. In India, Dr. S.V. Desai developed the first biogas plant.
Frequently Asked Questions (FAQs)
"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.
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.
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.
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.
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.
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.
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.
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.
Questions related to
On Question asked by student community
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.
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.
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.