Biogas Digester-in-a-bag Brings Portability
Biogas is fuel made from biodegradable organic material such as kitchen, animal or human waste. it can be converted into gas either by being heated or using anaerobic bacteria to break down the material and turn it into combustible methane gas.
Most biogas systems are complex and large, involving an enormous domed biodigester. But a clever solution from Kenya, the Flexi Biogas system, is different. It is designed to be highly portable and scalable depending on a person’s needs. The Flexi Biogas system is a pillow-shaped PVC tarpaulin, measuring 6 metres by 3 metres. It comes in two parts: a plastic digester bag on the inside and a greenhouse-like plastic tunnel on the outside. The tunnel traps heat and keeps temperatures between 25 and 36 degrees Celsius.
Subjected to the heat of the sun, the environment inside the bag encourages microbes to digest the organic material, or substrate as it is known, releasing biogas bubbles and inflating the bag with methane. This gas is then sent through a PVC tube that can be connected to a gas-burning appliance such as a cooking stove.
Currently, most people use the biogas for lighting and cooking but the system also produces enough gas to run agricultural machinery.
The Flexi Biogas digester sits on the ground and thus is easy to observe and understand.
The Flexi Biogas system is designed, built and sold by Kenya’s Biogas International, which has sold 200 of the systems since 2011. In 2012, the company partnered with – the United Nations’ International Fund for Agricultural Development ( IFAD) to install nine systems on dairy farms in Kenya. These Flexi Biogas systems use kitchen and human waste to produce electricity for lighting and to provide Internet service. – (December 2012)
1 2 3 The Flexi Biogas digester filled with gas. Assembling the Flexi Biogas system. Filling the Flexi Biogas digester with excrement. • biogas.co.ke • ifad.org
Flexi Biogas digester before it has filled up with gas.