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close this bookBetter Farming Series 32 - Biogas 2: Building a Better Biogas Unit (FAO, 1986, 47 p.)
View the document(introduction...)
View the documentPreface
View the documentIntroduction
Open this folder and view contentsHow to build a better small biogas unit
Open this folder and view contentsPutting in the waste
View the documentTime
Open this folder and view contentsTemperature
View the documentScum
View the documentWhen the gas is made
View the documentTaking care of your biogas unit
View the documentMaking more biogas
Open this folder and view contentsWhat more can you do?


1. You have already built one or more biogas units like the one described in the Better Farming Series Booklet No. 31; Biogas: what it how it is made; how to use it.

Biogas unit

2. When you first began you found that you had to learn a lot of new things in order to make your unit work.

3. However, little by little you have learned more and more through your own experience.

4. When your first gas was made you used it for cooking. You found that cooking with gas was cleaner, easier and faster than cooking with kerosene, charcoal or fuelwood.


5. Now that you know more about biogas and how it is made, let us look at another way to make biogas even better.

6. In this booklet you will learn how to build and use a better small biogas unit like the one shown below.

biogas unit

7. It too has an oil drum for a waste holder and, like your first small unit, all the waste is put in at one time when you begin.

8. However, the new unit is closed. A closed unit is cleaner. You cannot smell the waste after you have put it in as you could with your old unit.

9. In addition, with your old unit some of the gas was lost from around the open sides of the oil- drum waste holder.

Gas lost

10. Since the new unit is closed you will not lose any gas. You can collect it all so you will have more gas to use.

No gas lost

11. Notice in the closed unit (see the drawing above) that the oil drum is filled nearly to the top with waste. There is little space to hold gas.

12. So, you will need something to collect the gas. In the new unit, the gas holder is a used inner tube as you can see in the drawing on page 2 in this booklet.

13. This new biogas unit looks much like your old unit and it works in much the same way. You already know a lot of the things that you need to know to put this new unit together.

14. However, before you begin it would be a good idea to read Booklet No. 31 again.

Biogas unit