Biogas

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
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
 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)
 Methane
CO2
Biogas H2S
O2
Amonio
+ ENERGY

Water with 80-90%

Water, Excreta,
Organic Material, less contaminants,
Organic Fertilizer
Biodegradable Waste Anaerobic Environment

Hydrolysis, Fermentation,
Acetogenesis,
Dehydrogenization,
Methanogenesis

(3)
Graphic courtesy of Raul Botero
Technical Requirements for Biodigestor

pH
Temperature (4)
Time
Ratio of water to waste
Ratio of carbon to nitrogen (5)
Fats and Grease
Food Processing Waste
Cultivation Waste
Whey (without salt)
Manure

Biomass
Relative Biogas Production

(3)
 Effluent
• Fertilizer (6)
• Only 90% pathogen free
• Sulabh Effluent Treatment
-sedimentation
-filtration
-UV radiation (7)
• Tilapia pond (8)
 Digest Digest
er er Percent USEP
Influen Effluen Reductio A CIIU*
t t n Limit 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% 35 200
Turbidi
ty
(NTU) 1818 172 90.5% 50
TKN
(mg/L) 306 166 45.7% 15 50
43.9%
NH4-N Increas
(mg/L) 46.1 82.2 e 2 (3)

13.6%
 Scrubber
• H2S - hydrogen sulfide
– Corrosive to metal parts of generator
– Component of biogas
• Steel wool scrubber (9)
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)
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
Designs/Models – China Fixed Dome

(11)
Design/Model – India Floating Cover
Gas Outlet

Floating Gas
Cover

Mixing
Pit Outlet Pit
Slurry Fluid Level
Inlet Pipe

Partition
Wall

(12)
 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)
 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: 33.84 m3 for 12 hours/day

(33.84 m3) * (1 / .4 m3/kg biomass) = 84.6 kg

horse manure
 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) = 44550 lbs

manure/dumpster
(13)
(44550 lbs/dumpster) * (1 kg / 2.2 lbs) = 20250
kg/dumpster

(20250 kg/dumpster) * (1 / 84.6 kg/day) =

239.36
days/dumpster
 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.

 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
 References
1 "Biodigester Design & Construction: Understanding the Basics of a Biodigester." Rural Costa Rica. 2007.
Rural Costa Rica. 5 Jun 2008 <http://www.ruralcostarica.com/biodigester.html?
gclid=CIil8pW8yZMCFSemQQodyUMLjQ>.

2 “3.1.2. Biogas.” Sustainable Energy Technologies Solutions for Poverty Reduction in South Asia. Inforse-
Asia: The International Network for Sustainable Energy. <http://www.inforse.org//asia/M_III_biogas.htm>.

3 Arnow, Josh. "bio gas." E-mail to Alix Simnock. 28 May 2005.

4 “Biogas Digesters.” Household Energy Options. Energy for Sustainable Development (ESD) Limited. 3 June
2008 <http://igadrhep.energyprojects.net/Links/Profiles/Biogas/Biogas.html>.

5 “The biogas plant-some technical considerations.” Bioconversion of Organic Residues for Rural
Communities. 1979. The United Nations University. 31 May 2008
<http://www.unu.edu/unupress/unupbooks/80434e/80434E0k.htm>.

6 Nagamani , B., and K. Ramasamy. "Biogas production technology: An Indian perspective." Indian Academy
of Sciences. Indian Academy of Sciences. 5 Jun 2008 <http://www.ias.ac.in/currsci/jul10/articles13.htm>.

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 <http://unapcaem.org/Activities%20Files/A01/Recycling%20and%20reuse%20of
%20human%20excreta%20from%20public%20toilets%20through%20biogas%20generation%20to
%20improve%20sanitation,%20community%20health%20and%20environment.pdf>.
 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. 2007. Todd Ecological Design, Inc.. 8 Jun 2008
<http://www.toddecological.com/ecomachines/design.html>.

9 “Biogas Scrubbing System (Eliminating Corrosive Hydrogen Sulfide Gas).” Energy Farms Network:
Reliable Renewable Energy for a Post Carbon World. 2006. Post Carbon Institute. 3 June 2008
<http://www.energyfarms.net/node/401>.

10 "Sichuan's Home-Scalae Biogas Digesters". Mother Earth News. 6/5/08

<http://www.motherearthnews.com/Renewable-Energy/1981-05-01/Sichuans-Home-Scale-Biogas-
Digesters.aspx>.

11 "Current Project: Small-Scale Biogas in La Florida". Appropriate Infrastructure Delegate Group. 6/5/08
<http://www.aidg.org/outreach/laflorida_biogas.htm>.

12 Beckmann, Curt. "Home biogas system (original)." Appropedia. MediaWiki. 5 Jun 2008
<http://www.appropedia.org/Home_biogas_system_%28original%29>.

13 Jokela, Bill. “Manure Spreader Calibration.” University of Vermont Extension. 9 June 2008
<www.sera17.ext.vt.edu/Documents/BMP_manure_spreader_calibration.pdf>
 ‘Someone somewhere has
found a solution’
The PACE project was started to help organisations in
one part of Africa get the benefits from the ideas and
experiences of people working in other parts. By
sharing ideas we don’t have to start from zero, we
can learn from other people’s experiences and share
our own findings with them, so everyone benefits.
The film we’re watching today has been shared with
people in 22 countries.
 ‘GOOD’ or ‘BAD’?
Sort these FUELS from BEST to WORST. There’s no right answer so think
about why you’ve chosen that order.

GOOD
Methane
Your legs A banana skin

A waterfall Coal
A cowpat

A tree
Uranium
The North Wind
Sunshine
BAD
 If you were a farmer in Tanzania,
? would you install a biogas system?

BENEFITS TO MY FAMILY PROBLEMS TO OVERCOME

Activity 1
 Find out more…

Also known Used for

as… lighting
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gases) ……………………………
What is it made ……………………………
from? Biogas ……………………………
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Benefits:
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How is it made:
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What is biogas?
• A mixture of methane and
carbon dioxide

CH4

CO2 • Methane or ‘swamp gas’,

produced
Whatnaturally
is this? in
swampy ponds
What is it used for?
• Biogas is a fuel used as an energy
?
source for light, heat or movement
How is it made?
Biogas is produced by the breakdown of organic
waste by bacteria without oxygen (anaerobic
digestion or fermentation).
Leftover food from houses,
shops, restaurants and factories

Leftover straw and

Cow, sheep and What types of organic waste could be
Sewage crops from farming
chicken manure turned in biogas?

Leftover meat and

blood from
abattoirs
How is it made?
Biogas is made by fermenting organic waste in a biogas
digester.

Digesters vary from small household

systems…
….to large commercial plants of several thousand cubic metres

Holsworthy Biogas Plant, Devon

• It can also be captured from landfill sites where
organic waste has been rotting under the ground
 KEYWORDS

environmental greenhouse
gases
biogas
Anaerobic Electricity generators at Holsworthy
electricity digestion

methane manure

organic waste pollution

CREATE A SENTENCE USING THE KEYWORDS TO

COMPARE THE TWO CASE STUDIES
Katakwa’s biogas stove