The entrance and exit of the biodigester may be reinforced with bricks and concrete to improve durability. Biodigester reservoir, in this case resting on top of the shade for the biodigester itself. This will produce enough gas to cook 3 meals a day for a family of 6 people. I t may be necessary to replace the polyethylene tube every two years since it is destroyed by the heat and the sun. A tube that is shaded will last longer, and this doesn't affect the efficiency of the biodigester itself, since it is heat rather than light which makes it work.
Carbon dioxide is produced when the methane gas is burned for cooking and heating.
This is the same carbon dioxide which was captured and fixed by the plants that are eaten by the animals that produce the manure, so there is no net increase in carbon dioxide in the atmosphere. This means that biogas is a green fuel. There is a further gain. If you didn't put the animal manure through the biodigester first, but just spread it on the land straight from the animal, the methane would still be produced, and methane is a much more potent greenhouse gas than carbon dioxide, so by capturing it with a biodigester and burning it, you are doing the environment a favor. A manual on recycling livestock wastes was recently prepared on three CD-ROM disks.