Biogas Digestion
by
Michael Klima
[email protected]
What is Biogas Digestion?
• Biogas Digestion is the process of taking
biogas to produce electricity, heat, or hot
water
• Biogas means a gas formed by carbon
dioxide and methane from breakdown of
organic materials such as manure.
What is a Digester?
• Digester is a vessel or container where the
biogas process takes place. Bacteria breaks
down manure or other waste products to
create biogas. Products may be fed into
the chamber such as manure or the
container could be used to cover a place
that is already giving off biogas such as a
swamp or a landfill.
History of Biogas
1808 – Sir
Humphrey Davy
found that
methane was
present in the
gases that is
formed by the
Anaerobic
Digestion of
manure
1895 – Biogas is
used to light up
the streets in
Exeter, England
1884 – Louis
Pasteur student,
Ulysse Gayon,
performed the
anaerobic
fermentation of
manure and
water at 35ºC
and obtained
100 liters of
Biogas per cubic
meter of
Manure.
1957 – A British
Inventor, Bates,
modifies his car
to run on Biogas
produced from
pig manure.
2005 – The
Biogas Support
program in
Nepal wins the
Ashden Reward
for installing
over 150,000
Biogas Plants in
rural areas. And
a Biogas
powered train
starts it's service
in Sweden
Reasons of Interest in Biogas
Anaerobic Digester systems
• Improved Technology in systems has led
to reliability
• Good way to manage manure given the
odor and environmental concerns
associated with manure
• Government has subsidized programs
for systems
• Potential to sell credits to utilities and
utilities continue interest in green
energy
Biogas Process
Design of a Digester
How Digester Works
• Temperature must be kept between 65 degrees
and 150 degrees
• 4 Types of bacteria breakdown the waste
– Hydrolytic breaks organic material to simple
sugar and amino acids
– Fermentative then converts to organic acids
– Acidogenic convert to carbon dioxide,
acetate, and hydrogen
– Methanogenic produces biogas
Combined Heat and Power
• Also known as cogeneration
• Using the heated water for other
purposes such as heating buildings or
creating additional energy
Sources of Biogas
•
•
•
•
•
Wetlands
Sewage Sludge
Landfills
Plant Material
Animal Waste
TYPES OF BIOGAS DIGESTER
SYSTEMS
Number of United States
Operating Anaerobic Digesters by
Technology
• Complete Mix Digester – Are larger
vessels that can either be above or
below ground. They are used for
larger amounts of manure
• Plug Flow Digester- Is used for
ruminant animal manure and
requires little maintenance. Better
for smaller operations
• fixed film digester – “a tank
designed as part of a manure
management system to handle
manure up to 3 percent solids. The
digester is temperature controlled
and a media is placed inside the
digester. This design allows the
microbial populations to attach to
the media and grow as a biofilm
(fixed film), thus preventing the
microbes from being removed with
the effluent”
• temperature-phased anaerobic
digester (TPAD) – “two tanks
designed as part of a manure
management system. The digesters
are heated, the first digester in the
thermophilic temperature range
and the second digester in the
mesophilic temperature range. This
will maximize biological activity for
the destruction of volatile solids,
methane production and odor
reduction.”
• covered lagoon digester – “an anaerobic
lagoon is commonly used when manure
has less than 2 percent solids.
Decomposition of the manure occurs,
methane is produced and effluent odor is
reduced. The lagoon is covered with a
gas-tight cover to capture the biogas.”
• A landfill gas-to-energy – “consists of a series
of wells drilled into the landfill. A piping
system connects the wells and collects the
gas. Dryers remove moisture from the gas,
and filters remove impurities. The gas
typically fuels an engine-generator set or gas
turbine to produce electricity. The gas also
can fuel a boiler to produce heat or steam.
Further gas cleanup improves biogas to
pipeline quality, the equivalent of natural
gas. Reforming the gas to hydrogen would
make possible the production of electricity
using fuel cell technology.”
US Government Involvement
Regulations
• On March 20, 2009 revised the new
source performance standards to limit
when owners/operators of stationary
combustion turbines using biogas had
to install emission controls and/or
pretreatment systems to remove sulfur
compounds
• Biogas is recognized as an advanced
biofuel under 42 U.S.C.A. § 7545
Financial Incentives
• Since 2003 USDA has awarded 37
million to anaerobic digestion systems
EPA AGSTAR Study of Two
farms
Parameter
With anaerobic digestion
Odor
Substantial reduction
Greenhouse gas emissions
Methane—substantial reduction (3.03 tons per cow-yr on a carbon
dioxide equivalent basis) Nitrous oxide—No evidence of emissions
with or without anaerobic digestion
Ammonia emissions
No significant reduction
Potential water quality impacts
Oxygen demand—substantial reduction (8.4 lb per cow-day)
Pathogens—substantial reduction (Fecal coliforms: ~99.9%) (M.
avium paratuberculosis: ~99%) Nutrient enrichment—no reduction
Economic impact
Significant increase in net farm income ($82 per cow-yr)
Benefits and Concerns
Benefits of Biogas Digester
Systems
• Odor Reduction by using raw manure
• If Ammonia, a by-product of process,
is captured can be used to help plant
growth by injecting it into the ground
• Reduction of Electricity for Farms
• Carbon Dioxide generated from
biogas digester systems creates less
greenhouse gas then methane gas
used in initial process
Biogas Digester System
Concerns
• Releases Nitrogen and ammonia into the
atmosphere both of which hazardous
• Can release Hydrogen Sulfide a very toxic
gas
• Methane released can create explosive
atmosphere
• Should raw materials get into water supply
can contaminate the water
• Transportation is of a concern because
methane is explosive although new
technology may allow it to be stored in
powder form
Current U.S. Examples
• Central Vermont of 158,000
customers 4,000 have agreed to pay
a small premium to use biogas
energy
• Panda Ethanol Plant in Texas
• Columbia Boulevard Wastewater
Treatment Plant in Portland, Oregon
produces 1.5 million kilowatts of
energy per year
Other Countries use of Biogas
•
•
•
•
Nepal
Africa
Ecuador
Sweden
Nepal
• Since 2003 Nepal has built 94,425
small biogas plants for individual use
• One plant costs approximately $593
USD (2009 estimate)
• Nepal has subsidized half the cost for
farmers willing to build these biogas
plants
• Nepal has targeted farmers with at
least one cattle and owns a small
piece of land
Benefits from Nepal's
Prospective
• Saves from deforestation because main
source of Nepal’s farmers power is wood
burning
• Has created 13,000 jobs since 2003 for
those who build these small plants
• Reduces air pollution because biogas
burns cleaner then wood
• Improves women and girls lives because
the plants reduce overall work by about 3
hours then collecting and cooking with
fire wood leaving more time for education
Africa
• Biogas distributors cost about
$50 per family
• Currently Nigeria is working on
a biogas project that will
provide gas to 5,400 people
and cost $300k
Ecuador Biogas Sewage
Project
• A large education complex called
Santa Maria del Fiat did not have
proper sewage system and would
simply dump waste in open spaces.
This contaminated underground
water sources and created sever
odors
• The project built a biogas digester
that processed both human and
animal waste
Ecuador Biogas Sewage
Project Continued
• The school also built a water
reclamation system
• During school year the 500 students
waste is used to produce over 40% of
the school’s gas electricity. Power is also
produced in the summer from local
farmer’s animal and vegetable waste
• The school sells the fertilizer by product
and uses the fertilizer in the schools
own orchid
Sweden Biogas Train
• Train runs on entrails of slaughtered
cows
• Costs 20% more to run on methane
then diesel right now
• Sweden is 10 times ahead of its
European counter parts for binding
goals the European Commission as
setup for use of bio-products by the
end of the year 2010
• Sweden also has 65 fleet of biogas
buses
Conclusions
• Biomass counts for only 4% of
United States yearly energy use
• Biogas works best on small scale
operations
• Has technology improves we will
be able to use methane gas more
efficiently
• Good way to put human and
animal waste to good use
Notes-Citations
•
•
•
•
•
•
•
•
•
•
•
Slide 3-http://www.biogas.psu.edu/terminology.html
Slide 4-http://www.biogas.psu.edu/basics.html
Slide 5-http://www.energyrevolution.co.za/biogas/biogas-history
Slide 6- http://www.epa.gov/agstar/documents/2010_digester_update.pdf
Slide 7-http://www.hydropur.be/anglais/Assainissement%20et%20biogaz
/biogas%20principle.html
Slide 8-http://www.clearhorizonsllc.com/html/products/diagram.htm
Slide 9-http://www.oregon.gov/ENERGY/RENEW/Biomass/biogas.shtml
Slide 10-http://www.epa.gov/chp/basic/index.html
Slide 11-http://www.epa.gov/chp/basic/index.html
Slide 12- Various sources see
Slide 13-No need for citation
Notes-Citations Continued
•
•
•
•
•
•
•
•
•
•
•
Slide 14-http://www.epa.gov/agstar/documents/2010_digester_update.pdf
Slide 15-http://www.biogas.psu.edu/terminology.html
Slide 16-http://www.biogas.psu.edu/terminology.html
Slide 17-http://www.biogas.psu.edu/terminology.html
Slide 18-http://www.biogas.psu.edu/terminology.html
Slide 19 -http://www.oregon.gov/ENERGY/RENEW/Biomass/biogas.shtml#
Landfill_Gas
Slide 20- No Citation needed
Slide-21- SO2 EMISSION LIMIT FOR UNITS BURNING BIOGAS ADDED TO NSPS FOR
STATIONARY COMBUSTION TURBINES (19 NO. 4 Air Pollution Consultant 2.13)
Slide 22-http://www.epa.gov/agstar/documents/2010_digester_update.pdf
Slide 23- http://www.epa.gov/agstar/documents/nydairy2003.pdf
Notes-Citations Continued
•
•
•
•
•
•
•
•
•
•
•
•
Slide 24-No citation needed
Slide 25-http://animalagteam.msu.edu/Portals/0/anaerobic.pdf
Slide 26-http://www.biogas.psu.edu/Safety.html
Slide 27-http://www.nytimes.com/2008/09/24/business/businessspecial2/
24farmers.html
Slide 28-No need for a citation
Slide 29-http://www.bspnepal.org.np/achievements
Slide 30-http://www.bspnepal.org.np/target-group
Slide 31 – Borders and Environment by Andrew P. Morriss and E. Roger Meiners 39
Envtl. L. 141)
Slide 32-http://sgp.undp.org/download/SGPCaseStudiesBook.complete.pdf
Slide 33-http://sgp.undp.org/download/SGPCaseStudiesBook.complete.pdf
Slide 34-http://news.bbc.co.uk/2/hi/science/nature/4373440.stm
Slide 35-http://tonto.eia.doe.gov/kids/energy.cfm?page=biomass_home-basicsk.cfm