Ibadan, the second largest city in Nigeria, is the center of a large agricultural region in Oyo State. Since the nineteenth century, fierce intertribal rivalries and other political unrest have pushed large influxes of refugee and military populations into the city. This chaotic growth has discouraged the kind of municipal infrastructure that is taken for granted in the developed world. Soon, however, Ibadan’s power needs, at least, will get a boost from a relatively simple but extremely effective source of energy that is increasingly finding favor across Africa:
Biogas technology, which converts biological waste into energy, is considered by many experts to be an excellent tool for improving life, livelihoods, and health in the developing world. Worldwide, about 16 million households use small-scale biogas digesters, according to Renewables 2005: Global Status Report, a study by the Worldwatch Institute. The Ibadan plant will be one of the larger biogas installations in Africa, providing gas to 5,400 families a month at around a quarter the cost of liquefied natural gas.
The Ibadan digester will take advantage of the city’s Bodija Municipal Abattoir, where nearly two-thirds of the animals in Oyo State are slaughtered, according to a study in the January 2002 African Journal of Environmental Assessment and Management. The wastes from the slaughtering process are rinsed into open drains that connect to surface water; they also percolate into groundwater. About 60% of Ibadanians get water from hand-dug wells vulnerable to contamination from surface sources, and about 15% have private wells tapping a deep aquifer, according to Tijani Moshood, a geologist at the University of Ibadan.
Abattoir waste carries high levels of microorganisms that cause disease in humans and animals, such as Salmonella and Escherichia coli bacteria, Rift Valley fever virus, and parasites that cause toxoplasmosis and trichinellosis. Pesticides, antibiotics, metals, industrial chemicals, and the agents responsible for bovine spongi-form encephalopathy (BSE) may also enter the human food chain at an abattoir if they are present in the animals. Furthermore, decomposing organic material releases methane and carbon dioxide (CO2). CO2 is a primary culprit in climate change, but methane is even worse—23 times more potent than CO2, according to the Intergovernmental Panel on Climate Change report Climate Change 2001: The Scientific Basis.
Fortunately for the people of Ibadan, the new plant should mitigate many of these hazards. The project, dubbed Cows-to-Kilowatts, is a joint venture among the Nigerian branch of the Global Network for Environment and Economic Development Research, a nongovernmental organization (NGO); the Biogas Technology Research Centre of King Mongkut’s University of Technology in Thonburi, Thailand; the Centre for Youth, Family and the Law, a Nigerian NGO; and the Sustainable Ibadan Project, which is part of UN-HABITAT. Cows-to-Kilowatts was a 2005 winner of the Supporting Entrepreneurs for Environment & Development (SEED) Awards, which honor outstanding new entrepreneurial ideas for sustainable development worldwide.
Joseph Adelegan, a civil engineer and project director for Cows-to-Kilowatts, estimates the project will cost around US$300,000. Startup funds have been procured, and construction of the new plant is expected to begin by July 2006. The Ibadan system will employ a sophisticated design known as an anaerobic fixed-film digester, in which the active microorganisms are attached to an inert medium. The fixed-film technique shortens the time it takes for complete digestion, which enables the digester to be more compact.