Introduction to Biogas, May 4, 2009

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Rosalie Forest Eco Lodge

ECOFEST 2009

Introduction to Biogas, May 4
th
, 2009

Presented by


Vincent Martineau

Jessica Worley


Who We Are








Vincent Martineau, B.Eng Bioresource


Focused on sustainable technologies, water management and land
development.


Jessica Worley, B.Eng Civil and Applied Mechanics


Specialty in geoenvironmental engineering and water resource
management.

Obtained biogas experience in Barbados during the Fall of 2007

Overview


Goals & Objectives


Anaerobic Digestion


Biodigesters


Biogas


Design Specifications


Recommendations



Source: www.knowledgepublications.com

Source: www.knowledgepublications.com

Goal

Design and construction of a biodigester to produce
biogas

Objectives





Create a source of fuel for cooking;




Provide a fertilizer from the digested waste;
and




Improve health conditions by isolating wastes
in a sealed container to reduce airborne
pathogens from raw manure.



What is a Biodigester?


A device that mimics the natural decay process of organic matter


Biogas is produced from anaerobic decay (decay that occurs without
oxygen)


Anaerobic Digestion in a Biodigester



Digester is fed a mixture of water and waste
called a
slurry



Daily, fresh slurry is added, displacing previous
days load that bacteria have started to digest



First, digestible organic matter is broken down
by
acid
-
producing

bacteria



By
-
products are then broken down by
methane
-
producing

bacteria

(
journeytoforever.org/biofuel_library
/)

Bi
o
gas:

Green

Energy



50
-
70% methane;


30
-
40% carbon dioxide;


Insignificant amounts of oxygen and hydrogen
sulfide (
H
2
S
).


Biogas burns without soot or ash being produced


Methane is a combustible gas


Biogas will be used to generate energy for the
cooking needs here at Rosalie Forest Eco Lodge

(plascoenergygroup)

History of Biogas




One of the oldest forms of renewable energy



Marco Polo mentioned the use of the technology.
Probably goes back 2000
-
3000 years ago in ancient
Chinese literature



The earliest evidence of use in Assyria (10
th

century BC)



History of Biogas




Jan Baptita Van Helmont determined in
1630 that flammable gases could evolve
from decaying organic matter.



Anaerobic digestion first described by
Benjamin Franklin 1764.


Count Alessandro Volta in 1776 found a
correlation between amount of decaying
organic matter and amount of flammable
gas produced.


In 1808, Sir Humphrey Davy determined
that methane was present in the decay
process.




History of Biogas Cont’d



First digestion plant was built in 1859 in Bombay, India for a leper
colony



Exeter, England, in 1895: biogas used to power street lamps



1920’s and 30’s interest in anaerobic digestion increased



Interest in Biogas has been cyclical




Examples of Digesters Around the World


Costa Rica

Digesters Around the World (cont’d)


India (ARTI)

Digesters Around the World (cont’d)


United States

Princeton, Minnesota

Princeton, Minnesota

Digesters Around the World (cont’d)


KVIC Digester (used in India and China)

Prototype

Work log of what we did


Design Advantages



Reduction in scum accumulation


Temperature Control


Ease of operation


Durable


Small footprint


Low cost



What Type of Waste Produces Biogas?



Any organic waste can produce biogas


Human, manure, fruit and vegetable waste


What Type of Waste Does NOT Produces Biogas?


Fiber rich waste such as wood, leaves, etc. are difficult to digest


Heavy metals


Inorganic materials in high concentration (Nitrate, Sodium, Sulphate,
Sodium, Potassium, Calcium, Magnesium, etc)

How Much Biogas Can I Get From My Waste?



Amount of biogas depends on the waste itself and design of the
digester.



Some digesters can yield 20 liters of biogas per kilogram of waste up to
800
liters
per kilogram.



Factors:

waste quality, digester design, temperature, system operation,
presence of oxygen.

How Much Energy is in Biogas?



Average fuel value of methane = 1000 BTU/ft3



Average fuel value of propane = 2500 BTU/ft3



1 BTU/ft3 = 37.2589 KJ/m3

How Much Energy is in Biogas?



Therefore, using the SI system, Fuel Value units:



FV methane =
1000

* 37.2589 KJ/m3 = 37258.9 KJ/m3


FV propane =
2500

* 37.2589 KJ/m3 = 93147.3 KJ/m3


FV propane / FV methane = 2.5



When both fuels are burned completely, propane produces 2.5 times
more energy per unit of volume.

How Much Biogas Do I Need?



For Example
: We want 40 lbs of propane
-
equivalent per week.



Biogas is 50
-
70% methane, 30
-
50% CO2 and 5
-
15% N2, H2, etc.



40 lbs propane * 2.5 = 100 lbs of methane



100 lbs of methane / 60% = 166.67 lbs of biogas



Specifications



Input:

1 kg of donkey manure, 1 kg of food waste and 15 liters of water



Volume of tank:

55 US gal (~208.2 litres, ~0.208 cubic meter)


Assuming:


Total Solids (TS) ~15%


Volatile Solids (VS) ~70%


Hydraulic Retention Time: 10 days

How to calculate Organic Loading Rate (OLR)




OLR = kg VS added / day / m3 reactor



OLR = Manure * TS% * VS% / Volume



Organic Loading Rate: 2.02 kg VS added / day / m
3

reactor



How much money did we just save?



Methane production estimated at
XXX m
3
/day (equivalent to XXX kg of
propane/day)



Economic gain of about XXX $/year if fully used



Low Cost of construction: ~250 $EC

Obstacles



Economic: Keeping it
inexpensive



Time



Equipment: Limited



Weather: When it rains, it
pours!


Problem Solving



Recycled materials



Have friends around



Borrow and buy



Work in
-
between the
showers!


Implementation Plan




Research of existing technology and systems



Inventory of resources



Budget



Design



Construction



Testing



Cook!


www.journeytoforever.org

www.anaerobic
-
digestion.com/index.php

www.biogas.psu.edu

www.arti
-
india.org/content/view/12/28

www.ruralcostarica.com/biogas.html

http://www.fao.org/docrep/t0541e/T0541E00.htm#Contents





Resources

Thank You!

Questions?