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Biogas systems
Biogas is produced by the breakdown of organic waste by bacteria during anaerobic digestion. It is a mixture of gases, primarily methane and carbon dioxide. A biogas plant consists of a digester where the waste decomposes and a gas holder that captures the gases produced. Biogas can be used as a fuel for cooking, lighting, electricity generation, and transportation. While biogas has benefits such as being renewable and reducing pollution, some challenges to biogas adoption include plant failures and lack of technology advancement to produce cleaner gas.
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Biogas systems
- 1. Environmental Sustainability throughGreening the industries-2017 Biogas Technology Ruwan Wijemanne Energy Expert- NCPC
- 2. ‘GOOD’ or ‘BAD’? Sortthese FUELS from BEST to WORST. Methane Coal The Wind Cow dung A banana skin A tree Sunshine A waterfall Furnace oil Uranium GOOD BAD
- 3. Used for ………………………………… ………………………………… ………………………………… ………………………………… ………………………… How isit made:……………….. ……………………………………………………………… ……………………………………………………………… ……………………………………………………………… ……………………………………………………………… ……………………………………………………………… ……………………………………………………………… ……………………………………………………………… ………………………………………… Also known as… …………………………………… ……(A mixture of gases) Benefits:………………… ………………………………………… ………………………………………..… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………… Biogas Find out … What is it made from? …………………………………………………… …………………………………………………… …………………………………………………… …………………………………………………… ……………………………………………………
- 4. Content • Biomass asan energy source • Biogas Generation • Technical variants • Applications
- 5. Introduction What is Biogas? •Most organic matter begins the process of decomposition when it is exposed to oxygen and sunlight. • However, organic matter can also decompose without any oxygen, by the process of anaerobic fermentation. • This happens due to the bacteria present in the matter which acts during the absence of oxygen.
- 6. What is biogas? •A mixture of methane and carbon dioxide CH4 CO2 • Methane or ‘swamp gas’, produced naturally in swampy ponds What is this?
- 7. • It canalso be captured from landfill sites where organic waste has been rotting under the ground
- 9. • Landfills seea lot of such decay, especially when the waste material becomes wet and receives little sunlight. • As a result, a lot of methane and nitrous oxide is produced and released into the atmosphere. • Biogas is the result of this decay, and it is an energy source like no other.
- 10. In other words •Biogas typically refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. • Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste. • It is a renewable energy source and in many cases exerts a very small carbon footprint.
- 11. • Biogas canbe produced by anaerobic digestion with anaerobic bacteria, which digest material inside a closed system, or fermentation of biodegradable materials
- 12. • Biogas isprimarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulfide (H2S), moisture and siloxanes. • The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. • 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.
- 13. Biogas is primarilymethane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulfide (H2S), moisture and siloxanes. Calorific Value: 21 MJ/kg (37 MJ/m3)
- 14. History of Biogas 1808– Sir Humphrey Davy found that methane was present in the gases that is formed by the Anaerobic Digestion of manure 1884 – Louis Pasteur student, Ulysse Gayon, performed the anaerobic fermentation of manure and water at 35ºC and obtained 100 liters of Biogas per cubic meter of Manure. 1895 – Biogas is used to light up the streets in Exeter, England 1957 – A British Inventor, Bates, modifies his car to run on Biogas produced from pig manure. 2005 – The Biogas Support program in Nepal wins the Ashden Reward for installing over 150,000 Biogas Plants in rural areas. And a Biogas powered train starts it's service in Sweden
- 15. What is itused for? • Biogas is a fuel used as an energy source for light or heat
- 16. What is itused for? • Biogas is a fuel used as an energy source for light or heat • Cooking 0.2 m3/of biogas per person/day • 1 lamp 0.15 m3/of biogas per hour • engines 0.7 m3/of biogas per kWh • Refrigeration • Transportation
- 17. Advanced applications • Biogasis a fuel used as an energy source for electricity generation
- 18. Advanced applications • Biogascan be compressed, the same way natural gas is compressed to CNG, and used to power motor vehicles. • In the UK, for example, biogas is estimated to have the potential to replace around 17% of vehicle fuel. • It qualifies for renewable energy subsidies in some parts of the world. • Biogas can be cleaned and upgraded to natural gas standards, when it becomes bio methane
- 19. Biogas is producedby the breakdown of organic waste by bacteria without oxygen (anaerobic digestion or fermentation). How is it made? Leftover food from houses, shops, restaurants and factories Cow, sheep and chicken manure Sewage Leftover meat and blood from abattoirs Leftover straw and crops from farming What types of organic waste could be turned in biogas?
- 20. Water, Excreta, Organic Material, BiodegradableWaste Hydrolysis, Fermentation, Acetogenesis, Dehydrogenization, Methanogenesis Methane CO2 Amonio H2SBiogas Anaerobic Environment Water with 80-90% less contaminants, Organic Fertilizer O2 Graphic courtesy of Raul Botero ENERGY+ (3)
- 21. The Main partsof a typical biogas plant consist of the following components:- • Inlet • Digester • Gas holder • Outlet There are different types of biogas production plants . The main two types are as follows :- • Fixed-dome Plant • Floating-drum Plants Biogas Plant
- 22. What is biogasplant? • A biogas plant is an anaerobic digester that produces biogas from animal wastes or energy crops. • Energy crops are cheap crops grown for the purpose of biofuels, rather than food. • Biofuels are liquid, gaseous, or solid fuel made from live or recently dead organic material known as biomass, as opposed to fossil fuels, which are composed of ancient biological materials.
- 23. • Biogas isa type of biofuel created via anaerobic, or oxygen-free, digestion of organic matter by bacteria. • A biogas plant is composed of a digester and a gas holder.
- 24. What is adigester? • The digester is an airtight container in which the waste is dumped and decomposed, and the gas holder is a tank that harnesses the gases emitted by the slurry. • Bacteria within the digester tank breaks down the waste and, as it decomposes, gases such as carbon monoxide, methane, hydrogen, and nitrogen, are released.
- 25. • Through apressurized system, the gas holder conducts the flow of these gases upward into a hole in its drum. • The hole is specially designed to allow gases to pass freely into the holder while prohibiting any gases from escaping back into the digester. • In a controlled environment, the gases are later combusted, or reacted, with oxygen to create an energy source for such processes as heating and vehicle propulsion
- 26. Biogas is madeby fermenting organic waste in a biogas digester. Digesters vary from small household systems… How is it made?
- 27. Lankan Dry BatchBiogas System • Batch type • Straw, cow dung, Urea • 2 weeks for growing media • 6 months retention time • 4 months retention for vegetable/ food waste • Need to fill 2/3 of Digester • Sludge is a good fertilizer
- 28. Chinese type biogassystem • Domestic food waste • Continuous type • Fixed dome • Channelling prevention wall
- 29. Fixed dome type •A fixed-dome plant consists of a digester with a fixed, non-movable gas holder, which sits on top of the digester • Advantage - The costs of a fixed-dome biogas plant are relatively low. It is simple as no moving parts exist. There are also no rusting steel parts and hence a long life of the plant (20 years or more) can be expected.
- 30. Chinese type biogassystem
- 31. Plug flow typebiogas system • Wet type • Market garbage • Continuous type • Fixed dome
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- 33. Floating dome type •Floating-drum plants consist of an underground digester and a moving gas-holder. • The gas-holder floats either directly on the fermentation slurry or in a water jacket of its own. • The gas is collected in the gas drum, which rises or moves down, according to the amount of gas stored • Advantage- Floating-drum plants are easy to understand and operate. They provide gas at a constant pressure, and the stored gas-volume is immediately recognizable by the position of the drum.
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- 35. Sausage Bag GasPlant Sludge used as a fertiliser Gas to kitchen Quick to construct May require importing May require protection from sharp objects & vermin Material is polyethylene plastic
- 36. Sausage Bag GasPlant
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- 38. • Qty ofsubstrate (feed rate) • Assess the biogas yield • Plan for usage • Size of components • Location • Cost Biogas Generation – Design
- 39. • Qty ofsubstrate (feed rate) Biogas Generation – Design Source Kg/day per animal Gas yield (l/kg) Cow 10 37 Buffalo 15 37 Human excreta 0.4 70 Pig 2.25 80 Poultry 0.18 61 • Digester selection Digester volume m3 Waste needed Kg/day Gas yield (m3/day) 6 25 1.5 8 50 2 10 75 2.5 12 100 3 • Size of digester for cattle field with 7 cows and gas rate ?
- 40. Retention time • Periodof occupation of material inside digester • RT = volume/ feed rate • Generally RT > 20 days • Wet AD process solid content of feed material < 10% Biogas Generation – Design Source RT Cow dung 20 Poultry 25 Piggery 20 Market waste Continuous
- 41. Sizing • Vd =SD x RT (m3) • Total Volume = V1 + Vd + V2 • Vd = π HD2 • V1 = 0.09 D3 • V2 = 0.04D3 • R1 = 5D/7 • R2 = 1.06 D • F1 = D/5 • F2 = D/8 Biogas Generation – Design
- 42. • Facilitate easyconstruction • Easy operation and maintenance • Safety • Temperature (>35 C) • Even surface, higher elevation for eliminate water logging • Sufficient distance from roots • 10m distance from water bodies Biogas Generation – Site selection
- 43. Suitable substrate • Animaldung • Human excreta • Vegetable • Food waste • Organic effluents • Mix of straw and dung • Fruit waste Biogas Unit – Operation
- 44. Favorable conditions • C:Nratioaround 25:1 • PH : 6-7 • Seed bacteria (floating BGM) • No sudden changes of feed rate • Isolation from free air • Agitation • Temperature (Soil temperature + 5 c) Biogas Unit – Operation Substrate C/N Urine 0.8 Cattle dung 10-20 Piggery 9-13 Fresh grass 12 Excreta 8 Straw 40
- 45. Other consideration • Shreddingfor fast reaction • Effluent discharging (if not used as bio fertilizer) • Pressure measurement by manometer Biogas Unit – Operation
- 46. Advantages of Biogas •Waste treatment – Reduce land fills – Reduce soil & water pollution • Energy Source – Renewable – Reduce GHG • Bio fertilizer (Agriculture) • Cheaper technology • Job opportunities Key disadvantages are : Little technology advancement, Not a clean gas & unstable
- 47. Failures 17% of plantsin Sri Lanka are not in operation • No responsible person • No adequate biogas production • Design failures • Non availability of feeding material
- 48. Cost benefit calculation •Assuming that , In a biogas plant when you have an input of 100 kg of food waste the bio gas yield will be approximately 30 meter cubic per day. • Methane presence of biogas is 70% • Biogas calorific value: 37 MJ/m3 • LPG calorific value: 48 MJ/kg • Investment: Rs. 650,000.00 • Calculate the cost benefit ?
- 49. would you installa biogas system? ? BENEFITS TO MY INSTITUTE PROBLEMS TO OVERCOME
- 50. Thank You..! • References -NERDC Presentation, Sunil Karunawardane - http://biofuellanka.com/biogas_plant.html