What really happens inside a biogas digester, and how can operators detect problems before gas production drops?
In recent years, small household biogas systems have become more popular across Africa, with more people investing in and using them. These systems convert everyday waste, such as food scraps and animal manure, into clean energy for cooking while helping households manage waste more effectively. Despite this, many biogas plants struggle to perform well throughout their intended lifespans. One common problem is when the conditions inside the system become unstable—something known as a “digester upset.” When this happens, the tiny organisms that produce methane gas are affected. Because these microbes are very sensitive, even small changes can reduce gas production or stop it altogether.
To address this challenge, researchers from Ashesi University, Heather R. Beem, Francis Aweenagua, Francis A. Gatsi, Jeremiah Takyi, and Myron N. V. Williams from Clark Atlanta University developed a relatively low-cost smart biogas digester. The system uses Internet of Things (IoT) technologies to continuously monitor conditions inside the digester. By providing real-time insights, operators can detect early signs of upset digestion and take action before performance declines.
Earlier studies to monitor biogas systems focused mainly on how much gas was produced, or used just one sensor to check things like temperature and acidity. This assumed that everything inside the system was the same throughout. In reality, that is rarely the case. The smart biogas digester addresses this gap by capturing data from multiple locations, providing a clearer picture of the biological and chemical processes occurring within.
The system has two main parts: a monitoring device and a web-based application platform. The monitoring device links the digester and uses sensors to collect environmental data. The web application stores this data on a cloud server and provides a customized interface to allow users to view and manage system information.
The digester is built from an Intermediate Bulk Container (IBC) tank and has three outlets to make it easier to use and maintain. The bottom outlet is for removing sludge that builds up over time, the side outlet allows users to discharge liquid slurry daily, and the top outlet collects the biogas produced during digestion. The side outlet also helps keep the slurry at the right level so that the leftover material, known as digestate, doesn’t touch the infrared temperature sensor inside the digestor. The tank’s exterior is painted black to reduce light penetration and prevent algae from growing.
The web application is a means for users to interact with the smart digester system. After creating a secure account, users can connect to their digester using a unique Device ID, giving them protected access to their system data. A visual dashboard shows both real-time and past performance, making it easy to track changes and make informed decisions. Users can also record when and how much waste they add to the digester and download both sensor and feeding records for further analysis.
