25-02-2013, 04:04 PM
Biogas
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DESCRIPTION
Biogas is a fuel which is produced from the
breakdown of organic matter. Students will
have an opportunity to create their own
biogas generators. At the same time, they
will learn about the chemical reactions which
occur during the breakdown of organic
material.
READINESS ACTIVITIES
Students should:
• have some knowledge of the types of
energy sources which are currently being
used.
• have a basic understanding of the biology
behind composting.
Introduction
A major concern for most people these days is the use and availability of energy. Canadians
spend a large portion of their earnings on gas, propane and oil. These fossil fuels are being
continuously used to a large extent. Because these forms of energy are non-renewable, their
availability will continue to decrease and costs will continue to go up. This has led to a
search for new energy sources.
Biogas
One excellent source of energy is Biogas. This is produced when bacteria decompose
organic material such as garbage and sewage, especially in the absence of oxygen. Biogas
is a mixture of about 60 percent methane and 40 percent Carbon dioxide. Methane is the
main component of natural gas. It is relatively clean burning, colorless, and odorless. This
gas can be captured and burned for cooking and heating. This is already being done on a
large scale in some countries of the world. Farms that produce a lot of manure, such as hog
and dairy farms, can use biogas generators to produce methane.
Advantages
Biogas energy offers many advantages. Biogas-powered electricity plants can be built
quickly, simply, and for much less money per kilowatt than coal, oil, or nuclear power
plants. Unlike these other current energy sources, Biogas is a renewable resource. Methane
is going to be produced by decomposition whether it is used or not. Methane is also an
important greenhouse gas and is a major contributor to the global warming problem. Biogas
provides an excellent source of energy that is helpful to the environment. Finally, the residue
from the burning of Biogas, called activated sludge, can be dried and used as fertilizer.
Procedure
1. Collect the slurry material and bring it to the lab. This is used to fuel the generator. It can
be manure, household garbage, grass clippings or other green plant material, or dried manure
from a garden supply store.
2. Build the generators and label them. Use figure 1 as a guide. The bent glass tube is called
a manometer. Insert this into one of the stopper holes. It is used to indicate how much gas
is being generated. It also allows for release of pressure if too much gas is produced. The
burner tip goes in the other hole.
3. Mix the fuel with water until it has the consistency of cream. This liquefied fuel is called
a slurry. Put the slurry into the container. Fill it about three-quarters full. This will prevent
foam from clogging the generator. The foam develops as gas is produced. Use funnels if
possible.
4. Plug the generator with the stopper and store it in a warm place. Optimum temperatures
are about 32-38 oC. Be sure the stopper fits the opening tightly. The only opening should
be through the manometer.
5. Record the types and amounts of components in the slurry. Record the date the generator
was created.
6. Check for gas production every day. Keep track of the date and any observations. When
the water in the manometer has risen, gas has been produced. Test that gas for flammability
by holding a match near the burner tip. BE VERY CAREFUL. The gas should not burn at
first. Keep testing every day or two until methane is produced.
7. When methane production stops, discuss possible uses for the remaining sludge. Answer
the following questions to help understand the lab.