biomass energy 541
Biogas is invisible and does not smell. When it is burned, it produces a clean
blue flame. Using biogas for cooking instead of solid fuels like wood reduces
illnesses from indoor cooking smoke (see Chapter 17), and reduces the pressure
to cut down trees for fuel. The material left behind after producing biogas can
be used as a high quality fertilizer. Burning biogas does not lead to climate
change and global warming.
Make a small biogas plant
The design of the biogas plant depends on the quantity and kind of wastes
you have, the climate, and the construction materials available. You can
collect biopgas in a tank or a 5 to 10 meter long sausage-shaped plastic bag.
Different kinds of animal and plant waste create different amounts of gas, so
it is difficult to say how many animals are needed to produce biogas.
Manure from cows, pigs, chickens, and even human waste can be used
to produce biogas. Cows produce the most, by far, and are the best source
of biogas fuel. To have enough fuel to cook every day (5 hours per day on a
2-burner stove), 4 or 5 cows are needed.
Before building a biogas plant, you must be sure you have enough waste
material available to generate the amount of energy for your needs.
A basic design for a biogas plant
➏ Gas burned
to make light
and heat
➊ Organic
matter and
water go in
➋ The material
ferments,
releasing
biogas
➌ Gas rises
to the top
Waste
➎ material is
removed
for use as
fertilizer
➍ Pipe carries gas
to the house
(To learn more about biogas and to contact organizations that build biogas
systems, see Resources.)
A Community Guide to Environmental Health 2012