Biomass PDF

4.15 BIOMASS Simply defined, biomass is all plant material, or vegetation, either raw or processed biomass. Cattle duno called wild or cultivated. Waste matter that is orga...

4.15 BIOMASS Simply defined, biomass is all plant material, or vegetation, either raw or processed biomass. Cattle duno called wild or cultivated. Waste matter that is organic in nature is all are termed as biomass wOod, household vegetable wastes, bagasse from sugarcane, Examples of this energy source include: Fast growing trees and grasses wheat straw. " Agricultural residues like used vegetable oils, sawdust, or wood chips " Wood waste like paper trash, yard clippings, municipal waste water Methane that is captured from landfills, livestock, and treatment. animal dung or cattle dung cakes are used directly as fuels in rural India in Dried very efficient. It produces smoke "chulhas". The use of biomass directly as fuel is notprimary type of fuel. Biomass can Biomass is a and has very low efficiency of burning. secondary fuel likes gobar gas or methane gas be used more usefully in producing. Natural Resources 131 entialla biomass is stoisolar energy that we can convert to electricity, fuel, and t Th°hhotsunthesis the enenv from the sun is stored in the chemical bonds of ahe Nantateral pialv biomas enev omes from three sources: agricultural crop NNNNes municqland industrial waste, and energy plantations. In addition, crops such as Nn, syr bevs gans, and kelp can be grown specifically for energv generation. 415.1 Conversion of Biomass for Energy The last s t most common, and simplest method is direct combustion or burning the biomass which poduces enengv for activities such as heating or cooking Currently. nameus technologies exist that convert organic material to commercial energy out of them few ae mentioned below: Alcohol Fermentation: With alcohol fermentation starches are converted to sugar and then to fuel alcohol. This alcohol is then distilled and separated. With veast, materials such as wheat, barley, potatoes, and sawdust can be converted to alcohol. Curently, ethanol is the product from fermentation that is used in internal combustion engines as alternative fuel. " Landfill Gas: Decomposing organic waste generates gas as it is anaerobically digested. Approximately 50% of this is methane, ie., amajor factor of natural gas. " Gasification: The newest method for electricity generation is known as gasification, This method captures 65-70% of the energy present in solid fuels burned, like by first converting it to combustible gases. These gases are then energy. we curentls burn natural gas, and create 4.16 BIOGAS Biogas is made from organic waste matter after it is decomposed. The decomposition breaks down the organic matter, releasing various gases. The main gases released methane, carbon dioxide, hydrogen and hydrogen sulphide. Bacteria carry decomposition or fermentation. The conditions for creating biogas have to be out the that is without any air and in the presence of water.Theorganic waste matter is anaerobic generall. animal or cattle dung, plant wastes, etc. These waste products contain carbohydrater proteins and fat material that are broken down by bacteria. The waste matter is Soakod in water to give the bacteria a proper medium to grow. Absence of air or important for decomposition because bacteria then take oxygen from the wasteOxygen is material itself and in the process break them down. Outlet for bio-gas Slurry of Cattle Dung and Water Floating Overflow Gas-holder. HkGas valve Tank Mixing Outlet Tank-> Inlet Blo-gas collects here Grouhd Level Inlet Pipe Spent Slurry Dung and Water -Outlet pipe Mixture Partition Wall Underground Digester Tank -Support for Pipe Fig. 4.15 Floating gas holder type plant There are two types of biogas plants that are used in use cattle dung. called 'gobar and are hence India. These plants mainly is made from cattle dung and water, called gobar gas plant. Generally, slury The two types of biogas plants are: which forms the starting material for these plants. Floating Gas Holder Type of Plant: A well is made out of called the digester tank. It is divided into two parts. One concrete. ThiS slurry is fed to the tank. The tank has a cylindrical side has the inlet, from where floats on the slurry and collects the gas dome made of stainless steel that type of plant is floating gas holder type of generated. biogas Hence, the name given to u for about 50 days. As more gas is made by the plant. The slurry is made to ferme bacterial inside cylindrical dome increases. The gas can be taken outfermentation, the pressule through outlet pipe. e  Natural Resources 133 decomposed matter expands and overflows into the next chamber in tank. This is then emoved by the outlet pipe to the overflow tank and is used as manure for cultivation purposes. Flxed Dome Type of Plant: A well and a dome are made out of concrete. This given to this type is called the digester tank. The dome is fixed and hence the name of the plant is similar to of plant is fixed dome type of biogas plant. The function and overflows into the the floating holder type biogas plant. The used slurry expands overflow tank. Slurry of Cattle Outlet for Dung and Water bio-Gas Mixing Slab Cover Tank Slab cover H+Gas Valve Dome Overflow Ground 4Tank Level Bio-gas Inlet Chamber Spent Slurry Dung and Water Outlet Mixture Chamber Underground Digester Tank plant Fig. 4.16 Fixed dome type Biogas Plants 4.16.1 Advantages of plant, the floating chamber is made of stainless holder typeof and supervision " In the floating gas and needs continuous maintenance steel. This is expensive not the fixed - holder type of biogas plant as arise in for non-rust. This does of concrete. everything here is made Biogas Plants 4.16.2Disadvantages of from a disadvantage that its volume is fixed. suffers damage to the concrete Fixed dome type of biogas increases inside, it may cause plant. So if the gas pressurehappen in the floating holder type of biogas dome. This does not 4.16.3 Uses of Biogas because biogas burns without smoke. fuel. This is a plant and is Biogas is used as cooking piped into kitchens directly from has hiah calorific value, can be cheaper in cost. less to run electric engines such as pumps, as they cause used Biogas can be air pollution.