1. Alix Simnock Brooke Myones Carrie Senft Dan Cohn
Biogas
Alix Simnock
Brooke Myones
Carrie Senft
Dan Cohn

2. What is Biogas? Clean, efficient source of renewable energy (1)
Made from organic waste
Produces methane
Anaerobic digestion (2)
Replaces non-renewable energy
Digested in an airtight container
Biogas is an efficient way to produce clean, renewable energy out of different types of organic waste.
The organic waste, such as manure, fuels the process, causing anaerobic digestion to take place and break down the waste, creating methane.

3. Why Have a Biogas Digester?
Replaces fossil fuels and other sources of nonrenewable energy
Simple, cost effective designs
Highly available fuel supply
Better usage of manure
- no longer polluting water
- no longer being burnt
Saves money
Decrease greenhouse gas emissions
Produces organic fertilizer
Go off tangent about fossil fuel usage e.g. leading to air pollution, deforestation ...BONUS POINTS

4. How Does it Work? Manure mixed with water to create slurry
Slurry is put into airtight digester
Anaerobic decomposition
Methane created and collected
Effluent produced and removed (1)
When discussing effluent bring up point of it being both sludge and liquid

5. Water, Excreta, Organic Material, Biodegradable Waste
Methane
CO2
Biogas
H2S O2
Amonio +
ENERGY
Water with 80-90% less contaminants, Organic Fertilizer
Water, Excreta, Organic Material, Biodegradable Waste
Anaerobic Environment
Hydrolysis, Fermentation, Acetogenesis, Dehydrogenization, Methanogenesis
(3)
Graphic courtesy of Raul Botero

6. Technical Requirements for BiodigestorpH
Temperature (4)
Time
Ratio of water to waste
Ratio of carbon to nitrogen (5)

7. Relative Biogas Production
Fats and Grease
Food Processing Waste
Cultivation Waste
Whey (without salt)
Manure
Biomass
Relative Biogas Production
(3)

8. Effluent Fertilizer (6) Only 90% pathogen free
Sulabh Effluent Treatment
-sedimentation
-filtration
-UV radiation (7)
Tilapia pond (8)

9. USEPA Limit CIIU* Limit COD (mg/L) 2968 472 84.1% 125 500 BOD (mg/L)
Digester Influent
Digester Effluent
Percent Reduction
USEPA Limit
CIIU* Limit
COD (mg/L)
2968
472
84.1%
125
500
BOD (mg/L)
467
96.2
79.4% 25
200
TSS (mg/L)
2209
319
85.6% 35
Turbidity (NTU)
1818
172
90.5% 50
TKN (mg/L)
306
166
45.7% 15
NH4-N (mg/L)
46.1
82.2
43.9% Increase 2
PO4-P (mg/L)
13.3
15.4
13.6% Increase 10
(3)

10. Scrubber H2S - hydrogen sulfide Steel wool scrubber (9)
Corrosive to metal parts of generator
Component of biogas
Steel wool scrubber (9)
The hydrogen sulfide gas can be scrubbed by corroding some other type of metal- in this case steel wool.
As gas pressure builds up in the digester the gas is forced through the steel wool on its way to the gasholder.

11. SMALL SCALE DIGESTERS:
Where Has it Been Used?
SMALL SCALE DIGESTERS:
10,000,000 in China
5,000,000 in India
40,000 in Cambodia
5,000 in Vietnam
3,000 in Colombia
500 in Costa Rica (3)
All of these are developing countries, which shows that this is cost effective and simple.

12. Is it Successful? China: Yes! Helped with energy shortage problem (10)
Costa Rica: Yes! Big in rural areas (1)
Middle East: Yes! Helped improve health and safety conditions (6)
Most successful in rural areas
CHINA: 30 years. Had an energy shortage problem for a long time, but the use of the equipment has become more prevalent and has been helping a lot. Alleviated a lot of non-energy related issues, such as waste disposal, health, and fertilizer supply. Have created multiple designs that are very simple and handmade.
POND
Costa Rica: yes, but not very well known. One very succesfull project in rural coasta rica, but is not as popular as it is in china.
Bedouin: used to burn old manure in the backyards, which released toxins into the air. Also burnt this manure where children were playing, and many children and women would get very badly burnt. The project initiating these biogas generators also helped educate women on the environment, helping socially as well.

13. Designs/Models – China Fixed Dome
(11)

14. Design/Model – India Floating Cover
Gas Outlet
Floating Gas Cover
Mixing Pit
Outlet Pit
Slurry
Fluid Level
Inlet Pipe
Partition Wall
(12)

15. Designs/Models- Santa Fe Women's Group –Costa Rica
Halting deforestation
Use of cow manure
Produces energy for cooking
1.9 meters deep *1.5 meters wide * 3 meters long biodigester
2:1 ratio of water to manure (1)

16. Calculations 100 goats’ and 15 people’s waste can produce 10 m3 of
biogas ( 3 )
1 kW generator can run on 5.64 m3 of biogas for 12 hours per day
6 kW generator: m3 for 12 hours/day
(33.84 m3) * (1 / .4 m3/kg biomass) = 84.6 kg horse manure

17. Calculations (continued)
30 yd3 dumpster filled to capacity 1-2 times per week
(30 yd3) * (27 ft3/yd3) = 810 ft3/dumpster
(810 ft3/dumpster) * (55 lbs/ft3 dry manure) = lbs manure/dumpster
(44550 lbs/dumpster) * (1 kg / 2.2 lbs) = kg/dumpster
(20250 kg/dumpster) * (1 / 84.6 kg/day) =
days/dumpster
(13)

18. Calculations (continued)
30 yd3 dumpster filled to capacity (1 “pull”) 1-2 times per week
Barn pays for hauler per month, based on number of stalls- estimated $50-$75 dollars/stall, for 28 stalls
(1400 $/month) * (1 / 8 pulls per month) = $175/pull
(2100 $/month) * (1 / 4 pulls per month) = $525/pull
Each pull costs the barn between $175 and $525.

19. Our Recommendation Biogas = yes: -Carbon neutral, renewable fuel
-no net increase in atmospheric greenhouse gas
Considerations:
-Time Labor
-Construction cost Waste disposal
-Fuel source Temperature and pH monitoring

20. References
1 "Biodigester Design & Construction: Understanding the Basics of a Biodigester." Rural Costa Rica Rural Costa Rica. 5 Jun 2008 <
2 “ Biogas.” Sustainable Energy Technologies Solutions for Poverty Reduction in South Asia. Inforse-Asia: The International Network for Sustainable Energy. <
3 Arnow, Josh. "bio gas." to Alix Simnock. 28 May 2005.
4 “Biogas Digesters.” Household Energy Options. Energy for Sustainable Development (ESD) Limited. 3 June 2008 <
5 “The biogas plant-some technical considerations.” Bioconversion of Organic Residues for Rural Communities The United Nations University. 31 May 2008 <
6 Nagamani , B., and K. Ramasamy. "Biogas production technology: An Indian perspective." Indian Academy of Sciences. Indian Academy of Sciences. 5 Jun 2008 <
7 Jha, P. K.. "Recycling and reuse of human excreta from public toilets through biogas generation to improve sanitation, community health and environment." United Nations Asian and Pacific Center for Agricultural Engineering and Machinery. United Nations Asian and Pacific Center for Agricultural Engineering and Machinery. 5 Jun 2008 <

21. References (continued)
8 Todd, John. "T H E E C O - M A C H I N E: Design and Construction." Todd Ecological, Inc. - Solutions For Water Planning and Management Todd Ecological Design, Inc.. 8 Jun 2008 <
9 “Biogas Scrubbing System (Eliminating Corrosive Hydrogen Sulfide Gas).” Energy Farms Network: Reliable Renewable Energy for a Post Carbon World Post Carbon Institute. 3 June 2008 <
10 "Sichuan's Home-Scalae Biogas Digesters". Mother Earth News. 6/5/08 <
11 "Current Project: Small-Scale Biogas in La Florida". Appropriate Infrastructure Delegate Group. 6/5/08 <
12 Beckmann, Curt. "Home biogas system (original)." Appropedia. MediaWiki. 5 Jun 2008 <
13 Jokela, Bill. “Manure Spreader Calibration.” University of Vermont Extension. 9 June 2008 <