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Here is a compilation of essays on ‘Biomass’ for class 7, 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Biomass’ especially written for school and college students.
Essay on Biomass
Essay Contents:
- Essay on the Introduction to Biomass
- Essay on the Sources of Biomass
- Essay on the Energy Conversion Process for Biomass
- Essay on the Applications of Biomass Energy
- Essay on the Environmental Impact due to Biomass Energy Conversion
- Essay on the Benefits of Biomass
- Essay on the Scenario of Biomass Energy in India
Essay # 1. Introduction to Biomass:
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Biomass a renewable energy source is biological material from living or recently living organisms, such as wood, waste, (hydrogen) gas and alcohol fuels. Biomass is commonly plant matter grown to generate electricity or produce heat. In this sense, living biomass can also be included, as plants can also generate electricity while still alive.
The most conventional way in which biomass is used however, still relies on direct incineration. Forest residues for example (such as dead trees, branches and tree stumps), yard dipping, wood chips and garbage are often used for this.
However, biomass also includes plant or animal matter used for production of fibers or chemicals. Biomass may also include biodegradable wastes that can be burnt as fuel. It excludes organic materials such as fossil fuels which have been transformed by geological processes into substances such as coal or petroleum.
Industrial biomass can be grown from numerous types of plants, including miscanthus, switch-grass, hemp, corn, poplar, willow, sorghum, sugarcane and a variety of tree species, ranging from eucalyptus to oil palm (palm oil). The particular plant used is usually not important to the end products, but it does affect the processing of the raw material.
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Although fossil fuels have their origin in ancient biomass, they are not considered biomass by the generally accepted definition because they contain carbon that has been ‘out’ of the carbon cycle for a very long time. Their combustion therefore disturbs the carbon dioxide content in the atmosphere.
Biomass is carbon, hydrogen and oxygen based. Nitrogen and small quantities of other atoms, including alkali, alkaline earth and heavy metals can be found as well. Metals are often found in functional molecules such as the porphyrins which include chlorophyll which contains magnesium.
Plants in particular combine water and carbon dioxide to sugar building blocks. The required energy is produced from light via photosynthesis based on chlorophyll. On average, between 0.1 and 1% of the available light is stored as chemical energy in plants. The sugar building blocks are the starting point for the major fractions found in all terrestrial plants, lignin, hemicellulose and cellulose.
Biomass does not add carbon dioxide to the atmosphere as it absorbs the same amount of carbon in growing as it releases when consumed as a fuel. Its advantage is that it can be used to generate electricity with the same equipment that is now being used for burning fossil fuels.
Biomass is an important source of energy and the most important fuel worldwide after coal, oil and natural gas. Bio-energy, in the form of biogas, which is derived from biomass, is expected to become one of the key energy resources for global sustainable development. Biomass offers higher energy efficiency through form of Biogas than by direct burning.
Application:
Bio energy is being used for- Cooking, mechanical applications, pumping, power generation.
Some of the devices- Biogas plant/gasifier/burner, gasifier engine pump sets, Stirling engine pump sets, producer gas/biogas based engine generator sets.
Essay # 2. Sources of Biomass:
Biomass energy is derived from five distinct energy sources:
(i) Garbage,
(ii) Wood,
(iii) Waste,
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(iv) Landfill Gases, and
(v) Alcohol Fuel.
Wood energy is derived both from direct use of harvested wood as a fuel and from wood waste streams. The largest source of energy from wood is pulping liquor or ‘black liquor’, a waste product from processes of the pulp, paper and paperboard industry.
Waste energy is the second-largest source of biomass energy. The main contributors of waste energy are municipal solid waste (MSW), manufacturing waste and landfill gas. Biomass alcohol fuel or ethanol is derived primarily from sugarcane and corn. It can be used directly as a fuel or as an additive to gasoline.
Biomass can be converted to other usable forms of energy like methane gas or transportation fuels like ethanol and biodiesel. Methane gas is the main ingredient of natural gas. Smelly stuff, like rotting garbage and agricultural and human waste, release methane gas – also called ‘landfill gas’ or ‘biogas’.
Crops like corn and sugar cane can be fermented to produce the transportation fuel, ethanol. Biodiesel, another transportation fuel, can be produced from left-over food products like vegetable oils and animal fats. Also, biomass to liquids (BTLs) and cellulosic ethanol are still under research.
Essay # 3. Energy Conversion Process for Biomass:
There are a number of technological options available to make use of a wide variety of biomass types as a renewable energy source. Conversion technologies may release the energy directly, in the form of heat or electricity, or may convert it to another form, such as liquid biofuel or combustible biogas. While for some classes of biomass resource there may be a number of usage options, for others there may be only one appropriate technology.
(i) Thermal Conversion:
These are processes in which heat is the dominant mechanism to convert the biomass into another chemical form. The basic alternatives are separated principally by the extent to which the chemical reactions involved are allowed to proceed (mainly controlled by the availability of oxygen and conversion temperature): Combustion, Torre faction, Pyrolysis, Gasification.
There are a number of other less common, more experimental or proprietary thermal processes that may offer benefits such as hydrothermal upgrading (HTU) and hydro processing. Some have been developed for use on high moisture content biomass, including aqueous slurries and allow them to be converted into more convenient forms.
Some of the applications of thermal conversion are combined heat and power (CHP) and co-firing. In a typical biomass power plant, efficiencies range from 20-27 %.
(ii) Chemical Conversion:
A range of chemical processes may be used to convert biomass into other forms, such as to produce a fuel that is more conveniently used, transported or stored or to exploit some property of the process itself.
(iii) Biochemical Conversion:
A microbial electrolysis cell can be used to directly make hydrogen gas from plant matter. As biomass is a natural material, many highly efficient biochemical processes have developed in nature to break down the molecules of which biomass is composed and many of these biochemical conversion processes can be harnessed.
Biochemical conversion makes use of the enzymes of bacteria and other micro-organisms to break down biomass. In most cases micro-organisms are used to perform the conversion process: anaerobic digestion, fermentation and composting.
Other chemical processes such as converting straight and waste vegetable oils into biodiesel is trans-esterification. Another way of breaking down biomass is by breaking down the carbon-hydrates and simple sugars to make alcohol. However, this process has not been perfected yet. Scientists are still researching the effects of converting biomass.
Essay # 4. Applications of Biomass Energy:
The practical application of biomass energy includes:
(i) Bio-Gas Plants,
(ii) Biomass Briquetting,
(iii) Electricity Generation, and
(v) Bio Fuel etc.
(i) Biogas Plants:
Biogas is a clean and efficient fuel, generated from cow-dung, human waste or any kind of biological materials derived through anaerobic fermentation process. The biogas consists of 60% methane with rest mainly carbon-di-oxide. Biogas is a safe fuel for cooking and lighting. By-product is usable as high-grade manure.
A typical biogas plant has the following components:
A digester in which the slurry (dung mixed with water) is fermented, an inlet tank – for mixing the feed and letting it into the digester, gas holder/dome in which the generated gas is collected, outlet tank to remove the spent slurry, distribution pipeline(s) to transport the gas into the kitchen and a manure pit, where the spent slurry is stored.
Biomass fuels account for about one-third of the total fuel used in the country. It is the most important fuel used in over 90% of the rural households and about 15% of the urban households. Using only local resources, namely cattle waste and other organic wastes, energy and manure are derived. Thus, the biogas plants are the cheap sources of energy in rural areas. The types of biogas plant designs popular are floating drum type, fixed dome-type and bag-type portable digester.
(ii) Biomass Briquetting:
The process of densifying loose agro-waste into a solidified biomass of high density, which can be conveniently used as a fuel, is called biomass briquetting. Briquette is also termed as “bio-coal”. It is pollution free and eco-friendly. Some of the agricultural and forestry residues can be briquetted after suitable pre-treatment.
A list of commonly used biomass materials that can be briquetted are given below:
CornCob, JuteStick, Sawdust, PineNeedle, Bagasse, CoffeeSpent, Tamarind, CoffeeHusk, AlmondShell, Groundnutshells, CoirPith, BagaseePith, Barleystraw, Tobaccodust, RiceHusk, Deoiled Bran.
Advantages:
Some of advantages of biomass briquetting are high calorific value with low ash content, absence of polluting gases like sulphur, phosphorus fumes and fly ash – which eliminate the need for pollution control equipment, complete combustion, ease of handling, transportation and storage because of uniform size and convenient lengths.
Application:
Biomass briquettes can replace almost all conventional fuels like coal, firewood and lignite in almost all general applications like heating, steam generation, etc. It can be used directly as fuel instead of total in the traditional chulhas and furnaces or in the gasifier. Gasifier converts solid fuel into a more convenient-to-use gaseous form of fuel called producer gas.
(iii) Electricity Generation using Biomass:
From the ancient time to the present, the most common way to capture the energy from biomass was to burn it to make heat. Since the industrial revolution this biomass fired heat has produced steam power and more recently this biomass fired steam power has been used to generate electricity. Burning biomass in conventional boilers can have numerous environmental and air-quality and advantages over burning fossil fuels.
Advances in recent years have shown that there are even more efficient and cleaner ways to use biomass. It can be converted into liquid fuels, for example or “cooked” in a process called “gasification” to produce combustible gases, which reduces various kinds of emissions from biomass combustion, especially particulates.
Electricity Generation using Biomass Gassifier:
Biomass gasifiers convert the solid biomass (basically wood waste, agricultural residues, etc.) into a combustible gas mixture normally called as producer gas. The conversion efficiency of the gasification process is in the range of 60-70%. The producer gas consists of mainly carbon-monoxide, hydrogen, nitrogen gas and methane and has a lower calorific value (1000-1200 kCal/Nm 3).
The ‘Biomass Gasification – Electricity Generation’ system is a technology which converts any kind of biomass energy with low heat value (such as waste from agriculture and forest and organic waste) into combustible gas and then feeds this gas to a generator for electricity generation.
Discovering the method of biomass gasification for electricity generation, can solve both problems of effective use of renewable energy and environmental pollution from organic waste. For this reason, the technology of biomass gasification for electricity generation attracts more and more research as well as applications. Thereby, this technology is being continuously optimised.
The model of biomass gasification for electricity generation can be realized as follows:
As shown, biomass gasification for electricity generation can be realized in 3 ways:
i. Fuel gas produced in a biomass gasifier enters directly into a boiler to produce steam, which then drives a steam turbine to generate electricity.
ii. The clean gas drives a gas turbine to generate electricity.
iii. The clean gas drives a gas engine to generate electricity.
Above pathways correspond to large-scale, medium-scale generation, respectively.
Today, commercially successful technologies for biomass generation using gas engines get wide application because of their small system capacity, nimble arrangement, low investment, compact structure, reliable technique, low running cost, simple operation and maintenance and their low demand for gas quality.
Main Composition of Biomass Gasification — Electricity Generation Systems Equipped with a Gas Engine:
The system is mainly composed of gasifier, gas cleaner and gas engine:
A gasifier is a system which converts solid biomass energy into combustible gas. Biomass is combusted imperfectly by way of controlling the flow of air into the gasifier to convert solid state into gas state, generating a combustible gas which mainly consists of H2, CO, CH4 and CnHm.
The gas temperature in the outlet of the gasifier is in the range 350°C ~ 650°C, depending on the type of gasifier. The gas contains impurities such as dust and uncracked tar. In order to meet the demand of reliable gas engine operation over a long period of time, it is necessary to clean the gas at temperatures below 40°C as well as to reduce the content of dust plus tar below 50 mg/Nm. After cleaning, the gas is fed into the gas engine to generate electricity.
In the gas engine, the gas is mixed with air, burns and drives the main shaft to rotate at a high speed. The latter then drives the generator to generate electricity. Through above procedure, any waste can be converted into electrical energy, thereby solving pollution problems from wastes.
Biomass Gasification Electricity Generation Systems Equipped with a Gas Engine:
Specifications of the set contain power outputs of 60 kW, 160 kW, 200 kW, 400 kW, 600 kW, 800 kW and 1000 kW with the largest power output of about 1.4 MW. For power outputs below 200 kW, down-draft fixed bed gasifier are commonly used.
A typical down-draft fixed bed gasification set for the generation of electricity is shown in the following figure:
This down-draft fixed bed gasifier, can feed in raw material continually. The inlet of raw material is located at the top of the gasifier, raw material falls into the gasifier from the silo or it is transferred to the gasifier by a screw conveyer. In the lower part, the gasifer is equipped with a rotatory grid driven by a gearcase. The grid rotates continuously to extract ashes, the latter then being removed from the gasifier.
For cooling and cleaning of the gas use, a multistep water-washing is used. It is a reliable and cheap system meeting the demand of the engine. The gas engine is designed on the basis of the ‘6250 diesel engine’ so that it meets the low pressure ratio required by the produced bio-gas. In addition, a mixer structure outside of the machine and a simple reliable electric ignition system is used.
In case of electricity generation with larger capacity, fluidized bed gasifiers are used. As the greatest power output of a single gas engine is up to 200 kW, a fluidized bed gasifier is used to drive several gas engines at the same time.
A diagram of a fluidized bed gasification electricity generation system is shown below:
The gasifier uses a cyclical fluidized bed and it has high gasification efficiency and a powerful output. Raw material is formed grain or broken biomass and impurities such as ash or particles are removed from above by a cyclone.
The temperature at the outlet of the gasifier is about 600°C ~ 650°C. Removal of dust from the gas and gas cooling is realised by means of multistep water-washing. Several gas engines with an output of 200 kW generate electricity in parallel.
Applications of Gasifier:
Water Pumping and Electricity Generation:
Using biomass gas, it possible to operate a diesel engine on dual fuel mode-part diesel and part biomass gas. Diesel substitution of the order of 75 to 80% can be obtained at nominal loads. The mechanical energy thus derived can be used either for energizing a water pump set for irrigational purpose or for coupling with an alternator for electrical power generation – 3.5 kW -10 MW.
Heat Generation:
A few of the devices, to which gasifier could be retrofitted, are dryers for drying tea, flower, spices, kilns for baking tiles or potteries, furnaces for melting non-ferrous metals, boilers for process steam, etc.
Direct combustion of biomass has been recognized as an important route for generation of power by utilization of vast amounts of agricultural residues, agro-industrial residues and forest wastes. Gasifiers can be used for power generation and available up to a capacity 500 kW. The Government of India through MNES and IREDA is implementing power-generating system based on biomass combustion as well as biomass gasification.
(iv) Bio Fuels:
Unlike other renewable energy sources, biomass can be converted directly into liquid fuels — biofuels — for our transportation needs (cars, trucks, buses, airplanes and trains). The two most common types of biofuels are ethanol and biodiesel. See Fig. 1.51.
Ethanol is an alcohol, similar to that used in beer and wine. It is made by fermenting any biomass high in carbohydrates (starches, sugars or celluloses) through a process similar to brewing beer. Ethanol is mostly used as a fuel additive to cut down a vehicle’s carbon monoxide and other smog-causing emissions. Flexible-fuel vehicles, which run on mixtures of gasoline and up to 85% ethanol, are now available.
Biodiesel, produced by plants such as rapeseed (canola), sunflowers and soyabeans can be extracted and refined into fuel, which can be burned in diesel engines and buses. Biodiesel can also made by combining alcohol with vegetable oil, or recycled cooking greases. It can be used as an additive to reduce vehicles emissions (typically 20%) or in its pure form as a renewable alternative fuel for diesel engines.
Essay # 5. Environmental Impact Due to Biomass Energy Conversion:
Using biomass as a fuel produces air pollution in the form of carbon monoxide, NOx (nitrogen oxides). VOCs (volatile organic compounds), particulates and other pollutants, in some cases at levels above those from traditional fuel sources such as coal or natural gas. Black carbon – a pollutant created by incomplete combustion of fossil fuels, bio fuels and biomass – is possibly the second largest contributor to global warming.
On combustion, the carbon from biomass is released into the atmosphere as carbon dioxide (CO2). The amount of carbon stored in dry wood is approximately 50% by weight. When from agricultural sources, plant matter used as a fuel can be replaced by planting for new growth. When the biomass is from forests, the time to recapture the carbon stored is generally longer and the carbon storage capacity of the forest may be reduced overall if destructive forestry techniques are employed.
Despite harvesting, biomass crops may sequester carbon. So for example soil organic carbon has been observed to be greater in switch-grass stands than in cultivated cropland soil, especially at depths below 12 inches.
The grass sequesters the carbon in its increased root biomass. Typically, perennial crops sequester much more carbon than annual crops due to much greater non-harvested living biomass, both living and dead, built up over years and much less soil disruption in cultivation.
Sustainability:
Biomass energy production involves annual harvests or periodic removals of crops, residues, trees or other resources from the land. These harvests and removals need to be at levels that are sustainable, i.e., ensure that current use does not deplete the land’s ability to meet future needs and also be done in ways that don’t degrade other important indicators of sustainability.
Because biomass markets may involve new or additional removals of residues, crops or trees, we should be careful to minimize impacts from whatever additional demands biomass growth or harvesting makes on the land.
Essay # 6. Benefits of Biomass:
When done well, biomass energy brings numerous environmental benefits—particularly reducing many kinds of air pollution and net carbon emissions. Biomass can be grown and harvested in ways that protect soil quality, avoid erosion and maintain wildlife habitat. However, the environmental benefits of biomass depend on developing beneficial biomass resources and avoiding harmful resources, which having policies that can distinguish between them.
In addition to its many environmental benefits, beneficial biomass offers economic and energy security benefits. By growing our fuels at home, we reduce the need to import fossil fuels from other states and nations and reduce our expenses and exposure to disruptions in that supply. Many states that import coal from other states or countries could instead use local biomass resources.
With increasing biomass development, farmers and forest owners gain valuable new markets for their crop residues, new energy crops and forest residues— and we could substantially reduce our global warming emissions.
Essay # 7.
Scenario of Biomass Energy in India:
India being an agrarian country there is easy availability of agricultural based mass which can be used to generate energy. Burning the biomass is the easiest and oldest method of generating energy and also the least efficient.
Over 70% of the population of India is in villages. Their electricity and steady supply of water are crucial for survival and for economic growth and social development.
Biomass exists in these villages and needs to be tapped intelligently to provide not only electricity but also water to irrigate and cultivate fields to further increase production of biomass (either as a main product or as a by-product), ensuring steady generation of electricity. An added bonus is the availability of waste biomass from the biomass gasified plant to be used as fertilizer.
Most common source of biomass is wood waste and agricultural wastes. In India development of biomass gasification has received serious attention with establishment of biomass research centers and gasifier action research centres at various locations spread all over the country.
These institutions have played a key role in up gradation and adaption of suitable technologies, testing, monitoring and development of biomass gasification systems. Studies reveal that the low grade of land suitable only for scrub vegetation can be turned to advantage and form an excellent source of biomass – fast growing trees and shrubs.
In India more than 2000 gasifiers are estimated to have been established with a capacity in excess of 22 MW and a number of villages have been electrified with biomass gasifier based generators. MNES has actively promoted research and development programmes for efficient utilization of biomass and agro-wastes and further efforts are on.
Biomass gasification offers immense scope and potential for:
i. Water pumping.
ii. Electricity generation: 3 to 1 MW power plants.
iii. Heat generation: for cooking gas – smokeless environment.
iv. Rural electrification means better healthcare, better education and improved quality of life.