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What is a biogas plant?
The anaerobic digestion plant
Image taken from flickr,allispossible.org.uk
“Methane productionof cow vs grass”
LicenceCC BY-NC-2.0
Steps of anaerobic digestion
Source of image, microbewiki https://microbewiki.kenyon.edu/index.php/File:Stages_of_anaerobic_digestion.JPG.jpg#filelinks
Types of anaerobic digestion plants
● Fixed Dome Plant;● Floating Drum;● Low-Cost Polyethilene Tube Digester;● and many more
Fixed Dome Plants: explanatory videoVideo su https://www.youtube.com/watch?v=PmBx5Zo8KZo
Image taken from energypedia https://energypedia.info/wiki/File:Nicarao_biogas.gif
Licence CC BY SA 3.0
Fixed Dome Plants- Fixed dome digester put below ground;
- Biogas pressure moves the substrate to the compensating tank. Biogas is mixed by produced biogas itself;
- costs are relatively low (no moving parts) and the duration of the plant is higher than 20 years (there is no steel, which could rust);
- its construction requires expert workers in masonry and plumbing;
- the digester volume is usually comprised between 5 m3 and 200 m3 and the biogas volume is not usually higher than 20 m3;
- biogas pressure in the fermenter is comprised between 60 mbar and 150 mbar;
https://energypedia.info/wiki/Fixed-dome_Biogas_Plants#Fixed-dome_Plants
Fixed Dome Plants
Fixed Dome Biogas Plant Video Youtubehttps://www.youtube.com/watch?v=PmBx5Zo8KZo
Source of image energypedia https://energypedia.info/wiki/File:Nicarao_biogas.gif
Licence CC BY SA 3.0
Floating Drum Plants
Source of image 1
energypedia https://energypedia.info/
wiki/File:Floatdrumscheme
waterjack_s.gif
Licence CC BY SA 3.0
Source of image 2 and 3 energypedia
https://energypedia.info/wiki/Biogas_Plant_by_ARTI
Licence CC BY SA 3.0
Floating Drum Plants- First introduced in India in 1956, the floating drum plant usually has a floating dome or cilinder working as internal biogas storage. Biogas storage can be made of steel;
- Biogas accumulates in the gasometer causing its movement;
- Usually investment and maintenance costs ar high (steel dome). For this reason, the plant was soon substituted by fixed dome digesters. But there is an exception. Indeed there is a household scale biogas plant made from Appropriate Rural Technology India, known as ARTI biogas, which has been recently introduced and that is realized with cheaper plastic water containers or with fiber glass containers;
- Its construction requires skilled workers for plumbing and for the welding of the steel gasometer;
- the volume of the digester usually goes from 5 m3 to 20 m3 for rural plants and from 20 m3 to 100 m3 for agroindutrial and institutional digesters;
- biogas pressures can reach 20 mbar;
- in the following, we will talk a little bit better about the ARTI biogas plant;
https://energypedia.info/wiki/Floating_Drum_Biogas_Plants
Low-Cost Polyethilene Tube Digester
Source of image energypedia https://energypedia.info/wiki/Low-Cost_Polyethylene_Tube_Digester
Licence CC BY SA 3.0
Low-cost Polyethilene Tube Digester
- polyethilene tube (two 300 micron plastic sheets) closed at the edges with two 15 cm PVC drainpipes and wound with rubber strap of recycled tire tubes;
- per conferire la forma tubolare, il digestore è parzialmente incassato nel terreno, lasciando esposta all'aria solo la parte superiore dove si accumula il biogas. Questa parte ha un volume ridotto, corrispondente a ¼ del volume del fermentatore. Pertanto, di solito altri gasometri tubulari in polietilene sono installati nelle vicinanze del fornello utilizzatore;
- the digester can have different sizes and it is possible to have multiple digesters working in parallel;
- biogas pressure is low, being at about 2 mbar;
- biogas plant construction requires less technical competences and less skills from professionals, with respect to the fixed dome and the mobile drum plant;
https://energypedia.info/wiki/Floating_Drum_Biogas_Plants
What is biogas?● Main components (CH
4 and CO
2)
CALORIFIC VALUE OF SOME FUELS
SUBSTANCE LOWER CALORIFIC VALUE [MJ/kg]
Dry wood 15
Dry charcoal 24
Unleaded gasolin 44
Kerosene 43,5
Diesel 43,5
Liquified petroleum gas
48,1
Biogas 27,2
Hydrogen 120
What is biogas composition?
Component Biogas from landfillBiogas from the
organic fraction of municipal solid waste
Methane 45% - 55% 60% - 70%
Carbon dioxide 30% - 40% 30% - 40%
Nitrogen 5% - 15% < 1%
Acido Solfidrico traces (ppm) traces (ppm)
Alogenated compounds (es. chloride)
from tens to hundreds of ppm
rarely present
Silicon organic compounds
ppm Present as ppm only with some substances (es. livestock manure)
Volatile organic compounds few ppm few ppm
Sulfidric acid, alogenated compounds and silicon organic compounds are corrosiveSome volatile organic compounds are carcinogenic
How to help the poor
Public image
taken from pixabay
AID
→ donations
(traditional philantropy)
GIVING OPPORTUNITIES
→ education, training, microcredit, social business
Let's continue to work!
Identify a local Indian organisation with which collaborate;
Analize the social, economical and cultural context;
Choose which kind of biogas plant promote in the community in order to tackle poverty and household pollution;
Thanks for the attention!
Sentinelle dell'Energia – SELENE – Social Promotion Association
www.grupposelene.net
M: +39/3407711315
Facebook: https://www.facebook.com/SentinelleDellenergia/
