|Better Farming Series 32. Biogas 2: Building a Better Biogas Unit (FAO Better Farming Series, 1986)|
|How to build a better small biogas unit|
· an oil drum of about 200 litres, to hold the waste
· a piece of pipe about 15 centimetres long and about 2 centimetres in diameter to fit the oil drum, for the gas outlet
· a pipe T- piece, to connect the gas outlet to the inner tube
· a piece of pipe about 10 centimetres long to fit the T- Piece
· a valve to fit the 1 10- centimetre pipe
The drawing on page 14 in this booklet shows you how these pipe fittings are attached to the oil drum.
· at least 12 metres of rubber or plastic tube, about 2 centimetres in diameter, for the gas lines
· one or more inner tubes, to collect the gas
· if you are using more than one inner tube, you will also need one or more small T- pieces to connect the inner tubes.
15. The oil drum should have one hole for putting in the waste and another hole for the gas outlet. Many drums have threaded holes with threaded plugs to close them.
16. Try to find an oil drum with threaded holes in the top. That way it will be easier to build this unit and to make it airtight.