1. CACTUS MOON EDUCATION, LLC www.cactusmooneducation.com
ENERGY FROM PLANTS AND ANIMALS
BIO-GAS
TECHNOLOGIES EDUCATION MODULE
(big01pp)
CACTUS MOON
EDUCATION, LLC

2. INDEX Slide 1 Title Slide Slide 2 Index Slide 3 Bio-Gas
Slide 4 Anaerobic Digestion
Slide 5 – 6 Landfills
Slide 7 – 8 Waste Water Treatment Plants (WTTP)
Slide 9 – 10 Concentrated Animal Feeding Operations (CAFO)

3. Bio-Gas
Bio-gas is a methane rich gas which is created during the decomposition of organic material.
It is an approximately 50/50 mix of methane and carbon dioxide along with some other impurity gases.
Bio-gas can be used as a fuel to produce heat or electricity.
The carbon dioxide and other impurities can be removed from bio-gas leaving the methane which can be injected into a natural gas pipeline.
Bio-Gas is a methane rich gas that is formed when organic material decays or decomposes. It is a mixture of methane and carbon dioxide. It has about one half the energy content of natural gas which is almost 100% methane.
Just like natural gas, bio-gas can be used as a fuel to heat water and make steam for industrial processes or to generate electricity. It can also be used as a fuel in engines and combustion turbines. The impurities in bio-gas can be removed leaving almost 100% methane. This can be injected into a natural gas pipeline and used alongside the “natural” natural gas.

4. Anaerobic Digestion
Anaerobic digestion is a process in which microbes digest solid organic material in an oxygen starved environment.
In the process of digestion the organic material bio-gas is formed.
The bio-gas can be collected and used as a fuel to produce heat or electricity or it can be “cleaned” to leave methane.
Organic material can be anaerobically digested in a landfill or in a digestion tank.
An anaerobic digester is a large tank in which a sludge of organic material is “digested” by tiny microbes. The microbes convert the organic material in the sludge into methane and carbon dioxide – bio-gas – which can be used as a fuel.
Microbes also digest organic material in landfills. Here, they also produce carbon monoxide and methane.

5. Landfills - 1
Organic material in a landfill will decompose and produce bio-gas.
Collection wells are drilled into the landfill and a gentle vacuum is used to extract the bio-gas from the landfill.
The bio-gas collected can be used on-site to produce heat or electricity.
The bio-gas can be transported by a pipeline for use off- site.
The methane can be extracted from the bio-gas and injected into a natural gas pipeline for use off-site.
A lot of the waste that goes into landfills contains organic material. Kitchen scraps, restaurant leftovers, yard trimmings all contain material that microbes can convert into bio-gas.
Collection wells can be drilled into a landfill to extract the bio-gas that the microbes generate. The gas can then be used as a fuel to provide heat or to generate electricity or it can be cleaned and injected into a natural gas pipeline.

6. Landfills - 2
The bio-gas can be used on-site or transported off-site in a pipeline. 4
Wells are drilled into the landfill 1
The wells are connected by a system of pipes 2
A vacuum/blower “pulls” the bio-gas out of the landfill 3
Collection wells are drilled into the landfill
The wells are connected together by a system of pipes and connected to a vacuum/ blower.
The vacuum/blower gently “sucks” the bio-gas out of the landfill. It is important not to suck too hard, otherwise air will be drawn into the landfill and will dilute the bio-gas. It is also important to suck hard enough to collect all of the bio-gas, otherwise some bio-gas will leak out into the atmosphere.

7. Waste Water Treatment Plants (WWTP) - 1
The water and sludge in raw sewage are cleaned at a WWTP so they may be returned safely into our environment.
The water goes through a series of processes in which it is gradually clarified and purified.
Finally it is disinfected and is clean enough to be discharged into rivers and streams.
The sludge is “digested” by micro-organisms in an Anaerobic Digester Tank.
In the digestion process, bio-gas is generated which can be used as a fuel to produce heat or electricity.
In a wastewater treatment plant solid waste is gradually separated from the water in the sewage using a series of screens and settlement tanks.
The solid waste is rich in organic material and can be “digested” by microbes in an anaerobic digestion tank.
In the digestion process, bio-gas is produced which can be used as a fuel.

8. Waste Water Treatment Plants (WWTP) - 2
Raw sewage enters the treatment plant and passes through a series of screens and settlement tanks until it is clean enough to be discharged into rivers and streams. 1
The sludge that is collected from the settlement tanks is pumped into a digester tank where microbes “digest” the sludge and generate bio-gas. 2 3
The bio-gas is generally flared but can be used as a fuel to generate electricity.
Raw sewage is gradually cleaned by separating the water from the solid material using a series of screens and settlement tanks. The water is cleaned sufficiently that it can be safely returned back into the environment.
The solid material, “sludge” that is collected during the cleaning process is pumped into a digester tank where it is digested by microbes. During the digestion process, bio-gas is generated.
Typically the bio-gas is “flared” or burned. This is to prevent the methane in the bio-gas from harming the environment. However, the bio-gas is a fuel that can be used to provide heat or generate electricity.

9. Concentrated Animal Feeding Operations (CAFO) - 1
Another source of organic material is the animal waste produced at an animal feed lot or CAFO.
In a dairy CAFO the manure is collected daily by hosing down the feed areas.
The manure is very wet and is perfect for introduction into an anaerobic digester tank.
The bio-gas collected from the digester tank can be used as a fuel to produce heat or electricity.
The manure from one dairy cow produces enough bio- gas to generate 200 Watts of electricity!
Animal waste is another source of organic material that can be used to produce bio-gas.
In a dairy, cow manure is collected several times a day by washing down the feed lanes where the cows stand.
The manure that is collected is very wet and is ideal for use in an anaerobic digester to produce bio-gas.
The bio-gas produced from the manure from an average dairy cow during a year can be used to produce enough electricity to keep two 100 Watt light bulbs burning all year long!

10. Concentrated Animal Feeding Operations (CAFO) - 2
Microbes digest the solid material in the manure and produce bio-gas 2
Manure is collected by hosing down the feed lanes and is transferred to a digester tank 1
The bio-gas is collected and may be used as a fuel on-site 3
The bio-gas can be transported through a pipeline for use off-site 4
The feed lanes at a dairy are washed down several times a day to remove the manure. The manure is pumped into an anaerobic digester tank.
The solid material in the manure is digested by microbes in the digester tank. During the digestion process bio-gas is produced.
The bio-gas is collected and can be used as a fuel on-site for heating or to produce electricity.
The bio-gas can be cleaned and dried and the methane separated from the carbon dioxide. The methane can then be pumped into a natural gas pipeline for use off-site.