Biogas - Sustainability Through Green Energy

1. Bio Gas …Sustainability Through Green Energy

2. GROUP 03

3. Introduction…..

4. What is Bio Gas ? Bio gas is a gaseous mixture It contains mainly methane ( CH4) and Carbon Dioxide (CO2) Ammonia (NH3) and Hydrogen Sulfide (H2S) are other trace gasses. They are obtained from anaerobic fermentation of biomass. The biogas generation from organic material can be shown by the stoichiometric equation below

6. Production Process of Biogas Biodegradable organic compounds Hydrolysis stage Enzymes Soluble monomers Acetinic/Acid forming stage Enzymes Acetic acid, H2 and CO2 Methonogenic stage Methonogenic bacteria Methane(CH4) & Residue or Sludge

8. Can cook 3 meals for a family with 4 members

10. Types of Bio Gas Digesters…

11. There are three types of digesters Dry batch type digester Continuous type digester Plug flow type digester

12. Plug-flow Type Anaerobic Reactor Plug-flow type anaerobic reactor is a relatively new technology The reactor type is constructed in different ways in different parts of the world India has developed this technology in a very simple way

13. Plug flow reactor 1 m3 volume can react for 10 kg of waste daily Gas generation is 1/3 of digester volume 1.3 m3 of gas can be generated from 4 m3 digester 1 m3 of bio gas is required for a family of 4 members for daily cooking

14. Advantage of Plug flow reactor Solid matter can be fed continuously Feedstock can be tree leaves, vegetable waste, restaurant/ kitchen waste, animal dung or any other organic matter which is bio- degradable Suitable for households, farms, institutions or small local authorities

15. Construction of plug flow reactor

17. When the feed rate is 7.5-10 kgm-3 of digester volume generation of biogas becomes optimum. Sizing of biogas digesters could be done based on this figure. Increasing the feed rate beyond this value tends to block the digester.

23. Case study of Bio gas plant in USJP…

24. As our case study we selected the bio gas plant in the USJP HemaEllawalaboys hostel. This bio gas was used for cooking puposes in the hostel canteen.

25. Current Issues Seperation of waste is not done properly at the canteens.

26. Food waste is being collected from only 4 of the 6 main canteens. Waste is not being put into the digester daily,therfore the daily requirement of waste is not being met. Waste tends to get accumiliated near the inlet and therefore an unpleasent smell is detected in the area.

27. Gas produced is not being stored when not in use. The sludge outlet acts as a mosquito breeding ground, and is a health hazzard There is a danger of someone falling into the dome through the sludge outlet because it is not covered.

28. Recommendations.. At the initial stage of usage, it is recommended to add manure as a bacteria medium so it will speed up the process of anaerobic bacterial digestion. ( Around 14 days are required initially to produce the gas) The waste must be put into the digester daily to ensure the continuation of the process.

29. In order to stop organic matter/waste from blocking the entrance, the waste should be pushed into the digester using a specialized rod.

30. The tank should be covered with a net, and a concrete/Ferro-cement slab should also be placed upon the tanks. To prevent the breeding of mosquitoes in the sludge outlet, fish can be added to the outlet. Engine oil can also be used for this purpose.

31. Since the gas which is produced is being wasted by not being used, we recommend the use of bottom-less barrels to store the evolved gas.

32. To prevent the gas that has already come out of the digester from going back into it, a “T” joint should be fixed at the end of the pipe line: one leading to the destination (ex: kitchen gas cooker), while the other should be placed in a bottle filled with water to maintain the pressure.

33. The pipe which goes from the digester should be reinforced to prevent bending at places, and also to prevent damage from the sun light. Since there are 6 potential canteens that waste can be collected from, it would be more productive to collect waste from these as well.By doing so the main problem which is the lack of organic matter can be resolved to some extent.

34. A program that encourages students to separate bio degradable waste from non-bio degradable waste should be carried out. Ex: at least 2 separate bins for bio degradable and non bio degradable waste should be given to each canteen

35. Kitchen waste such as root vegetables, should be chopped into smaller pieces prior to entering them into the digester. When adding vegetables into the digester, acidic vegetables such as cabbage, tomatoes, mangos...etc. should not be put into it. A separate person should be appointed in charge of the bio gas digester at the hostel to look over its maintenance requirements.

36. References Prof. NilanthiBandara, Senior Lecturer, Department of Forestry and Environmental Science, University of Sri Jayewardenepura. Mr. Sunil Welivita, Technical officer, Renewable Energy Department, National Engineering Research and Development Centre of Sri Lanka. Mr. D. M. Jothirathne, Public Health Officer, University of Sri Jayewardenepura.

37. Thank you