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Biogas typically comprises 60-65% methane (CH4), 35-40% carbon dioxide (CO2), and 0.5-1.0% hydrogen sulfide (H2S), along with traces of water vapor. It is approximately 20% lighter than air and has an ignition temperature of 650-750°C. The calorific value of raw biogas is around 20 MJ/m³ (4,713 kcal/m³).
Unlike Liquefied Petroleum Gas (LPG), biogas cannot be converted into a liquid state under normal temperature and pressure. The critical temperature for methane liquefaction is -82.1°C at a pressure of 4.71 MPa, making liquefaction complex and energy-intensive. However, biogas can be upgraded by removing impurities like CO2 and H2S and compressing it into cylinders for use in three-wheelers, cars, pickup vans, or stationary engines at remote locations.
Since Compressed Natural Gas (CNG) technology is already wellestablished, upgraded biogas (also called biomethane) which has similar composition and energy content can serve as a direct substitute for CNG in all its applications. The calorific value of upgraded biogas (with CO2 removed) increases to around 34 MJ/m³, compared to 20 MJ/m³ for raw biogas.
Techniques for Biogas Purification
To enrich biogas and increase its methane content, various purification methods are employed:
1. Water Scrubbing
This physical absorption process involves pressurizing biogas and feeding it into the bottom of a packed column, while water is introduced at the top. The CO2 and H2S dissolve into the water as it flows downward, while methane rises and is collected. The water used can

3.1 Introduction

Nature has a provision for destroying and disposing off wastes and dead plants and animals. This decay or decomposition is carried out by tiny micro-organisms called bacteria. Making of farm-yard manure (FYM) and compost is also through decomposition of organic matter (OM). When a heap of vegetable or animal waste and weeds etc., die or decompose at the bottom of backwater or shallow lagoons, bubbles can be noticed rising to the surface of water. Sometimes these bubbles burn with dancing flame at dusk. This phenomenon has puzzled man for a long time. It was only during the past hundred years that Scientists unlocked this secret as the decomposition process. The gas thus produced was and is still called “Marsh Gas.” The technology of harnessing this gas under artificially created conditions is known as Biogas Technology.

12.1 Introduction

Nature has a provision for destroying and disposing off wastes and dead plants and animals. This decay or decomposition is carried out by tiny micro-organisms called bacteria. Making of farm-yard manure (FYM) and compost is also through decomposition of organic matter (OM). When a heap of vegetable or animal waste and weeds etc., die or decompose at the bottom of backwater or shallow lagoons, bubbles can be noticed rising to the surface of water. Sometimes these bubbles burn with dancing flame at dusk. This phenomenon has puzzled man for a long time. It was only during the past hundred years that Scientists unlocked this secret as the decomposition process. The gas thus produced was and is still called “Marsh Gas.” The technology of harnessing this gas under artificially created conditions is known as Biogas Technology.

11.1 General

Biogas is generated through a process of anaerobic digestion of organic materials. The materials normally used are human and animal waste, crop residues, agro-industrial waste and other biomass in a combination with water. Biogas production technology contributes in following ways:

(a)It provides a better and cheaper fuel for cooking, lighting and for power generation.

(b)It produces good quality, enriched manure to improve soil fertility.

(c)It provides and effective and convenient ways for sanitary disposal of human excreta, improving the hygienic conditions.

(d)It generates social benefits such as reducing burden on forest for meeting cooking fuel by cutting of tree for fuelwood, reduction in the drudgery of women and children etc.

(e)As a smokeless domestic fuel, it reduces the incidence of eye and lung disease.

(f)It also helps in generation of productive employment.

The biogas technology is primarily based on fermentation of cellulosic rich organic matter under anaerobic conditions. The methane producing bacteria become more active after the creation of anaerobic conditions, thus, the gas produced become rich in methane & carbon dioxide, beside traces of hydrogen sulphide, ammonia, oxygen, water vapour etc. depending on the feed material and other conditions. For burning of gas, it is necessary that methane contents should be more than 50 per cent. The complete knowledge of process of methane production including its chemistry, physiology, bio-chemistry, micro-biology and bacteriology has been studied over years in many parts of the world. The culture and isolation of microbes under various environmental conditions have been successfully experimented to improve rate of reaction. The conditions, under which cattle dung, organic wastes, bushes, weeds etc. will produce methane, can be understood through chemistry of fermentation.

8.1 Introduction

Biogas is produced by the anaerobic digestion of biodegradable materials with the help of microorganisms. Biogas is also considered as renewable energy source because of is environment friendly nature. Conversion of cattle dung, kitchen wastes and agricultural wastes into biogas have the potential to minimize the burden on the fossil fuel and reduce the environmental pollution. Majority of developing countries specially their rural and suburban areas faces lack of access to the electricity and cooking gas. Biogas technology is emerging as a sustainable technology for waste treatment which could help to tackle the waste disposal issue in developing countries. 

Bioagents like insects, pathogens etc., and other animals are used either to reduce growth or kill weeds.

But, not possible to eradicate weeds.

17.1 Introduction

Bioenergy is an array of energy produced by biomass (organic matter) including liquid, solid, and gaseous fuels, electricity, heat, steam, biochemicals and materials. Biofuel is any plant derived organic matter available on a renewable basis, including dedicated energy crops and trees, agricultural food and feed crops, agricultural crop wastes and residues, wood wastes and residues, aquatic plants, animal wastes, municipal wastes, and other waste materials. An organic matter such as wood, plants, residues from agriculture or forestry, and the organic component of municipal and industrial wastes that can now be used as an energy source. Today, many bioenergy resources are replenished through the cultivation of energy crops, such as fast-growing trees and grasses, called bioenergy feedstocks.

The biochemical oxygen demand is a chemical procedure for determining the amount of dissolved oxygen needed by aerobic organisms in a water body to break the organic materials present in the given water sample at certain temperature over a specific period of time. BOD of water or polluted water is the amount of oxygen required for the biological decomposition of dissolved organic matter to occur under standard condition at a standardized time and temperature. Usually, the time is taken as 5 days and the temperature is 20°C. microbes
C6H12O6 + 6O2 ¾¾¾¾®CO2 + H2O
Principle
The test measures the molecular oxygen utilized during a specified incubation period for the biochemical degradation of organic material (carbonaceous demand) and the oxygen used to oxidize inorganic material such as sulfides and ferrous ion. It also may measure the amount of oxygen used to oxidize reduced forms of nitrogen (nitrogenous demand).
Procedure
Fill two BOD bottles with sample (or diluted sample); the bottles should be completely filled.

Biomass briquetting is the process of compressing loose and low-density biomass materials such as sawdust, agricultural residues, and forest waste into high-density, solid fuel blocks called briquettes. The process involves mechanical compression under high pressure using machines like piston presses, screw extruders, or hydraulic presses, depending on the technology used.
The main purpose of briquetting is to increase the density of biomass to improve its combustion properties, handling, transportation, and storage efficiency. In most modern systems, briquetting is done without the use of binders, as natural lignin present in the biomass acts as a binding agent under pressure and heat.
Importance of Biomass Briquetting
Biomass briquetting holds immense environmental, economic, and social importance.
1. Environmental Protection
• Briquetting reduces deforestation by providing an alternative to firewood and charcoal.
• It minimizes air pollution by producing cleaner-burning fuel with lower particulate emissions and sulfur content.
• The process helps in carbon sequestration by ensuring the
sustainable use of biomass.
2. Waste Management
• Agricultural residues like rice husk, sugarcane bagasse, cotton stalks, and sawdust, which otherwise cause disposal problems, are effectively utilized.

Biomass is a renewable and valuable resource that has many uses, including energy production, biofuels, and bioproducts. It’s made up of a complex mixture of organic compounds like cellulose, hemicellulose, lignin, proteins, fats, and minerals, which can vary depending on the source and type of biomass. Understanding the composition and properties of biomass is essential for efficient use. In this chapter, we’ll provide an overview of how to analyze and evaluate biomass as a renewable energy source. We’ll cover various techniques and methodologies for analyzing biomass, including physical, chemical, and thermal properties. We’ll discuss the importance of biomass composition, moisture content, ash content, elemental analysis, calorific value, and other relevant parameters when assessing its suitability for energy conversion. Additionally, we’ll highlight the significance of biomass characterization in understanding biomass feedstock variability and its impact on energy production efficiency, environmental performance, and sustainability.

1.1 General

Biomass is a renewable and plentiful energy source with enormous potential to meet the rising demand for clean and sustainable energy solutions. This chapter offers an overview of biomass and its conversion technology, which includes various techniques to transform biomass into useful forms of energy like heat, electricity, and biofuels.

Biomass is an organic substance obtained from plants, animals, and microorganisms. It can be utilized as a source of energy or as a basic material in various applications. The energy in biomass is derived from photosynthesis, during which plants convert sunlight, carbon dioxide, and water into organic matter. Since it comes from living or recently deceased organisms, it is a sustainable and renewable resource. In terms of carbon dioxide emissions, biomass is considered a carbon-neutral energy source because the carbon dioxide produced during combustion is offset by the carbon dioxide absorbed by plants during their growth.

5.1 Introduction

The densification of biomass involves transforming loose and low-density organic materials, such as wood residues, agricultural waste, and plant-based materials, into compact and energy-dense forms. This process is necessary because natural biomass can be challenging to handle, transport, and store. Densification uses mechanical, thermal, or chemical processes to increase the material’s density and energy characteristics. The resulting products, such as pellets, briquettes, or cubes, offer several advantages, including higher energy content per unit volume, efficient storage and transportation, reduced moisture content, and improved combustion efficiency. These products are utilized in various industries, including energy production, residential heating, waste management, and industrial applications. Biomass densification promotes sustainable practices by effectively utilizing biomass resources, reducing waste, and promoting the use of renewable energy sources while mitigating environmental impacts.

2.1 Introduction

Biomass store solar energy in the chemical form and it is most precious and versatile resources on earth. Biomass, unlike fossil fuels, is a renewable energy resource that is available where the climatic conditions are favorable for plant growth and production¹. The term biomass is used for all organic materials which are combustible in nature, mainly plant and animal origin present in land and aquatic environments. Biomass is considered carbon neutral, because the amount of carbon it can release is equivalent to the amount it absorbed during its life time. There is no net increase of carbon to the environment in the long term when combusting the lignocellulosic materials. Therefore, we can say that biomass is a renewable source of energy and can play vital role in responding to concerns over the protection of the environment and the security of energy supply^2,3.

Biomass energy accounts for about 15% of the world’s primary energy consumption and about 38% of the primary energy consumption in developing countries⁴. Furthermore, biomass often accounts for more than 90% of the total rural energy supplies in developing countries⁵. It is the main source to meet out domestic energy in developing countries⁶. The efficient use of fuel wood is much more eco-friendly than the use of efficient and conventional fuels like kerosene and liquefy petroleum gas (LPG). LPG emits 15 times more CO₂ per kg than wood, and kerosene emits nearly 10 times as much. CO₂ is the prominent candidate for global. It is commonly assumed that biomass fuel cycles based on renewable in nature and greenhouse-gas (GHG) neutral because the combusted carbon in the form of CO₂ is soon taken up by re-growing vegetation⁷.

12.1 General

The term “biomass” generally refers to renewable organic matter generated by plants through photosynthesis. Materials having organic combustible matter is also referred under biomass. Biomass is an important fuel source in our overall energy scenario. Biomass is produced through chemical storage of solar energy in plants and other organic matter as a result of photosynthesis. During this process conversion of solar energy in sugar and starch, which are energy rich compounds takes place. The chemical reaction of photosynthesis can be written as:

6CO₂ + 6H₂ O + sun light → C₆ H₁₂ O₆ + 6O₂ + 636_kcal

It indicates that the storage of 636 kcal is associated with the transfer of 72 gm carbon into organic matter. Biomass can be directly utilized as fuel or can be converted through different routes into useful forms of fuel. In fact, biomass is a source of five useful agents, which start with `F’ like Food, Fodder, Fuel, Fiber and Fertilizer. Further, biomass has many advantages like.

5.1 Introduction

Biomass energy is the energy obtained from biomass or living things. Biomass is renewable organic material that comes from plants and animals. Plants generally produced through the process of photosynthesis as shown in Figure 5.1. Biomass is organic, meaning it is made of material that comes from living things, such as plants and animals. Wood, plants, and waste are the most common biomass energy sources. These are called biomass feedstocks. A plant absorbs the sun’s energy through photosynthesis and converts carbon dioxide and water into nutrients (carbohydrates). The energy from these materials can be transformed into usable energy through direct and indirect means. Biomass can be burned to create heat (direct), converted into electricity (direct), or processed into biofuel (indirect).

7.1 Introduction

Biomass gasification is age old technology originated in 1800 century for lighting and cooking purposes (Sansaniwal et al., 2017). Biomass typically contents biopolymers such as cellulose, hemicellulose and lignin in addition to the presence of average composition of C₆H₁₀O₅ which depends upon physical characteristics of biomass¹. Oxygen is required for combustion of every fuel. For complete combustion of biomass stoichiometric air to fuel ratio required varies from 6:1 to 6.5:1 with CO₂ and H₂O as end product.

Biomass gasification is an efficient and environmentally friendly way to produce energy². Gasification process is nothing but it is a conversion of solid fuel into gaseous fuel for wide applications. This whole process completed at elevated temperature range of 800-1300 ^oC with series of chemical reaction that is why it come under thermo chemical conversion³. Thermo chemical processes are most commonly employed for converting biomass into higher heating value fuels⁴. Major thermal conversion route is include direct combustion to provide heat, liquid fuel and other elements to generate process heat for thermal and electricity generation is summaries in Fig. 7.1.

A biomass gasifier is an advanced device designed to convert solid biomass materials-such as wood chips, crop residues, saw-dust, coconut shells, and other organic matter-into a combustible gas mixture known as producer gas. The conversion process, known as gasification, is a thermo-chemical process that takes place in a controlled environment with limited oxygen. Unlike complete combustion, gasification allows only partial oxidation of biomass, producing a gas rich in carbon monoxide (CO), hydrogen (H2), methane (CH4), and nitrogen (N2). This gas mixture can be used as a fuel for internal combustion engines, power generation, cooking, or industrial heating applications.
Principle of Gasification
Gasification involves a sequence of four key thermo-chemical reactions within the reactor, occurring at temperatures ranging from 800–1000°C:
1. Drying Zone: Moisture present in the biomass is evaporated due to the rising heat.
H2O (liquid) ? H2O (vapor)
2. Pyrolysis Zone: Biomass decomposes in the absence of oxygen to form volatile gases, tar, and solid char.
Biomass ? Char + Volatile gases + Tar
3. Oxidation Zone: A small amount of air or oxygen is introduced to partially combust the biomass, generating heat to sustain the process.

Biomass, a diverse and renewable resource, holds immense potential as a source of energy, feedstock, and environmental solutions. However, effectively harnessing its benefits necessitates a systematic approach. This chapter introduces the concept of Biomass Management Techniques as a pivotal framework for optimizing the utilization of biomass resources. With a focus on sustainable practices, this chapter delves into various techniques to handle, process, and utilize biomass efficiently. From collection and transportation to storage, conversion, and beyond, Biomass Management Techniques encompass a wide array of methods that ensure the seamless integration of biomass into energy generation, industrial processes, and environmental conservation.

6.1 Introduction

Biomass pellets are one of the most common types of biomass fuel. It is generally composed of wood waste, agricultural biomass, grasses, and forest residues, and is one of the most popular types of biomass fuel available today. Pelletization of biomass results in significant savings in terms of transportation, and storage, as well as the ease of handling biomass as a whole. In terms of flowability, dense cube pellets are similar to cereal grains in terms of their characteristics of being dense and cube-shaped. Due to their regular geometry and small size, biomass pellets are easily fed through an automatic feed system with fine calibration thanks to their regular shape. Because pellets are so dense, they can be stored in a compact way and transported over a long distance in a rational and efficient manner, because of their density. Furthermore, pellets can also be produced with a low moisture content, even though they are extremely dense. This allows them to burn with a high degree of combustion efficiency due to their low moisture content.