Biogas From Anaerobic Digestion


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Our Presentation Focus is on Alternate Energy Resource "Biogas Production From Anaerobic Digestion

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Biogas From Anaerobic Digestion

  1. 1. “What we are doing to the forests of the world is but a mirror reflection of what we are doing to ourselves and to one another.” Mahatma Gandhi “A nation that destroys its soils destroys itself. Forests are the lungs of our land, purifying the air and giving fresh strength to our people. ” Franklin D. Roosevelt
  2. 2. What is Bio Gas • Biogas is an alternative and renewable energy that can be produced by the anaerobic (absence of oxygen) decomposition of organic matter. • Biogas can be produced from regionally available raw materials such as recycled waste and is a renewable energy source • Typically, using organic wastes as the major input, the systems produce biogas that contains 55% to 70% CH4 and 30% to 45% CO2.
  3. 3. What is Bio Gas • Biogas is produced by anaerobic digestion with anaerobic bacteria orfermentation of biodegradable materials such as manure, sewage, municipal waste, green waste, plant material, and crops. • The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. • Landfill gas is produced by wet organic waste decomposing under anaerobic conditions in a landfill
  4. 4. What is Bio Gas • This energy release allows biogas to be used as a fuel; it can be used for any heating purpose, such as cooking. • It can also be used in a gas engine to convert the energy in the gas into electricity and heat. • Biogas can be compressed, the same way natural gas is compressed to CNG, and used to power motor vehicles
  5. 5. In the UK, for example, biogas is estimated to have the potential to replace around 17% of vehicle fuel.
  6. 6. Biogas Upgrading • Raw biogas produced from digestion is roughly 60% methane and 29% CO2 with trace elements of H2S So it is not high quality enough to be used as fuel gas for machinery. • The corrosive nature of H2S alone is enough to destroy the internals of a plant. • Methane in biogas can be concentrated via a biogas upgrader to the same standards as fossil natural gas, which itself has had to go through a cleaning process, and becomes biomethane
  7. 7. Biogas Upgrading • There are four main methods of upgrading: water washing, pressure swing absorption, selexol absorption, and amine gas treating • The most prevalent method is water washing where high pressure gas flows into a column where the carbon dioxide and other trace elements are scrubbed by cascading water running counter-flow to the gas
  8. 8. Reduced GHG emissions Potential reduction of VOC emissions Pathogen and weed seed control Improved water quality Benefits
  9. 9. Biogas In Pakistan National Bio Gas Program offer fix dom (6 m3 to 18 m3 ) small and medium bio gas plants is generally used for cooking and lighting purposes. Large units (25 m3 ,35 m3 , 50 m3, 100m3,200m3 )or more mega units produce this gas in large quantities and can be used, peter engines (tube wells , and Power Generation)
  10. 10. What is Biogas Digestion? • Biogas Digestion is the process of taking biogas to produce electricity, heat, or hot water • Biogas means a gas formed by carbon dioxide and methane from breakdown of organic materials such as manure.
  11. 11. What is a Digester? • Digester is a vessel or container where the biogas process takes place. Bacteria breaks down manure or other waste products to create biogas. • Products may be fed into the chamber such as manure or the container could be used to cover a place that is already giving off biogas such as a swamp or a landfill.
  12. 12. Manure collection and handling. Pre- Treatment Anaerobic digestion. By-Product recovery and effluent use Biogas Recovery Elements of Anaerobic Digestion Systems Biogas Handling and Use
  13. 13. How Anerobic Degestion Work
  14. 14. Design of a Digester
  15. 15. How Digester Works • Temperature must be kept between 65 degrees and 150 degrees • 4 Types of bacteria breakdown the waste – Hydrolytic breaks organic material to simple sugar and amino acids – Fermentative then converts to organic acids – Acidogenic convert to carbon dioxide, acetate, and hydrogen – Methanogenic produces biogas
  16. 16. Methanogenesis CO2 + 4 H2 → CH4 + 2H2O CH3COOH → CH4 + CO2 Chemistry Overall Reaction C6H12O6 → 3CO2 + 3CH4
  17. 17. • Hydrolysis: This is the first step where particulate materials get converted to soluble compounds suitable for further breakdown in the next step. • Acidogenesis: The second step of degradation is known as fermentation or acidogenesis where the products of hydrolysis such as simple sugars, amino acids, fatty acids etc. break down further and produce final products of fermentation such as H2, CO2 and acetate.
  18. 18. Combined Heat and Power • Also known as cogeneration • Using the heated water for other purposes such as heating buildings or creating additional energy
  19. 19. Biogas Digester System Concerns • Releases Nitrogen and ammonia into the atmosphere both of which hazardous • Can release Hydrogen Sulfide a very toxic gas • Methane released can create explosive atmosphere • Should raw materials get into water supply can contaminate the water • Transportation is of a concern because methane is explosive although new technology may allow it to be stored in powder form