biogas

BiogasAlix Simnock

Brooke Myones Carrie SenftDan Cohn

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)

Water, Excreta, Organic Material,

Biodegradable Waste

Hydrolysis, Fermentation, Acetogenesis,

Dehydrogenization, Methanogenesis

MethaneCO2

Amonio

H2S Biogas

Anaerobic EnvironmentAnaerobic Environment

Water with 80-90% less contaminants, Organic Fertilizer

O2

Graphic courtesy of Raul Botero

ENERGY+

(3)

Technical Requirements for Biodigestor

pHTemperature (4)

TimeRatio of water to waste

Ratio of carbon to nitrogen (5)

Fats and Grease

Food Processing Waste

Cultivation Waste

Whey (without salt)

Manure

BiomassRelative Biogas Production

(3)

Effluent• Fertilizer (6)

• Only 90% pathogen free

• Sulabh Effluent Treatment

-sedimentation-filtration-UV radiation (7)

• Tilapia pond (8)

Digester

Influent

Digester

Effluent

Percent Reductio

n

USEPA

LimitCIIU* 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

Turbidity

(NTU) 1818 172 90.5% 50

TKN (mg/L) 306 166 45.7% 15 50

NH4-N (mg/L) 46.1 82.2

43.9% Increas

e 2

PO4-P (mg/L) 13.3 15.4

13.6% Increas

e 10

(3)

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 China5,000,000 in India

40,000 in Cambodia5,000 in Vietnam3,000 in Colombia500 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

Mixing Pit

Inlet Pipe

Gas Outlet

Floating Gas Cover

Partition Wall

Fluid Level

Outlet Pit

Slurry

(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)

Calculations100 goats’ and 15 people’s waste can produce 10 m3 ofbiogas ( 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

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

(20250 kg/dumpster) * (1 / 84.6 kg/day) = 239.36 days/dumpster

(13)

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 monitoring

References1 "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>