I visited a UNDP managed project that is installing fixed-dome biogas digesters made out of brick and cement. The project is being carried out by an Indian NGO who were contacted for their expertise. SKG Sangha has worked in several continents and installed over 100,000 units. Mr. Keran is leading a team from this NGO and is super cool dude with a background of Philosophy and Education, and now 30 years of biogas.
He said to us very simply “Technology is for all, knowledge is for everyone.” As the units are being constructed, the UNDP has tasked Mr. Keran and his team to train masons before they leave and complete the transfer of technology and know how.
Here in Egypt, fifty will be installed in a village near Fayoum, about 90 minutes away from Cairo, Egypt and another fifty in Assyut, down south.
Size & Input
These biogas digesters which store about 4 cubic meters, function off of livestock dung, particularly cow manure. The initial stock required to get the unit started is about 4 tons of manure. The daily input would be a ratio of 1:1 with water, requiring about 100 kgs of manure to 100 kgs of water. Alternatively, the size of the unit can be reduced, however, this is a function of the average ambient temperature (Egypt= 20°C or 68°F). The larger size is designed to hold through the winter months as the process slows drastically and thus requires larger input to provide enough gas during the colder months. A friend told me they are exploring the use of a solar water heater as an added component to a smaller system, which would be more ideal to users. A smaller system of say 2 cubic meter, would require a daily input of 50 kgs manure (or the daily manure of 4 cows with each cow roughly producing 12 kgs of manure)
We visited a functioning unit and found the user really happy. He had managed to obtain the daily requirements without a problem. He used the specially designed stove to fire up what he needed in his kitchen. The unit was connected from the top with a pipe equipped with a valve to the kitchen.
Super Fertilizer & Subsidies
The important part to remember for Egyptian users: The farmer relies on the manure for fertilizer, but after its used in the biogas digester, the “slurry” output has 3 times the effect of regular manure because of its ability to retain moisture, among other reasons. So the farmer is never just throwing away such a vital component of his system. Actually, this unit’s main advantage for the Egyptian farmer is this slurry, while the gas is an added benefit. Mainly because they are still buying a 18 L. Gas cylinder, subsidized by the government for 6 EGP. However, it is widely speculated that these subsidies are not sustainable to the Egyptian government, and might very soon be altered, affecting the prices to farmers like those in Fayoum.
Took some pics. Check them out.
A 3D graphic model (almost the same design)