The Biogas Role in a Cassava Starch Factory in Nigeria: A Case Study
Roberto Preto, Marco Gottardo

Abstract
Biogas, as renewable energy form, can properly substitute conventional sources of energy (fossil fuels, oil, etc.) which are causing ecological–environmental problems as fast increasing of CO2 emissions. The biogas consists essentially of methane (CH4, 50÷75% by volume), carbon dioxide (CO2, 25÷45%) and water vapor (H2O, 2÷7%), as well as other gases in smaller concentrations, including hydrogen sulfide (H2S). The heating value of the biogas is a function of its content in CH4. On average the Net Heating Value can be considered equal to 20,000÷24,000 kJ/Nm3. Biogas plays a fundamental role for energy production in the food processing industries, a case study of a biogas implementation in a cassava starch factory in Bayelsa State, Nigeria is reported. Cassava peels and roots, wastewater from washing and cleaning cassava tubers are used in thermophilic / mesophilic anaerobic reactors to produce biogas suitably used in internal combustion engines. Hot water and electricity are produced, which are able to support the energy needs of the factory and the village located around it.

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