Africa’s household and agricultural waste is a valuable source of power that could be deployed to take clean energy to communities, complexes and individual homes at lower cost and faster return on investment than solar.
This is according to Vincent Okudoh, an associate professor in biotechnology at the Cape Peninsula University of Technology. He says biogas, which has been successfully tested and used for decades, is a safe, environmentally friendly and affordable source of power increasingly in use around the world.
Biogas is obtained through a biochemical process known as “anaerobic digestion”. This process involves the breakdown of organic wastes by methanogenic bacteria to produce mostly CH4 and CO2 plus other trace gases such as H2S, NH3 etc.
Since H2S is a smelly gas, research has been done to scrub it off from the mixture as well as CO2 thereby leaving what is termed an upgraded biomethane. It has now been researched by Okudoh and a colleague.
“Any concerns about possible risk or smell have been disproven or addressed, and biogas is now proving to be a win-win-win proposition for investors, waste producers and consumers,” he says.
Okudoh explains that biogas plants are now attractive easy-to-use facilities that could be installed in urban environments, at individual homes and shared by communities and residential complexes as a source of power.
He says, “I’m proposing and working on automated, self-contained home biogas systems, where home owners can dump all their food waste and benefit from their own power. Making it more consumer friendly and attractive will put it within reach of anyone, and we hope to see more African venture capitalists moving to produce these.”
Since 2014, Okudoh has been proposing the adoption of cassava biomass for sub-Saharan African biogas kick-off and has presented this in various global conferences.
“We are also looking at biological pre-treatment strategies for the recalcitrant lignocellulosic biomass,” he says.
“The original idea of anaerobic digestion started with cows, where it was determined that manure from one cow would be enough to light a house and cook meals. But the same principle applies to all organic waste such as grasses, residues and wasted food.
“Just 5kg of food waste and other organic matter that would previously have ended up in landfill can produce enough gas to cook a meal, boil a kettle and keep lights on. Contextually, an average cow yields about 10 kilograms of dung per day, which corresponds to 1 000 litre biogas, equivalent to 2.14 kWh (electricity) while 1 000 litres of biomethane equals 10 kWh. In South Africa, the average household uses about 9.4 kWh of electricity per day.
“We have researched the use of nanotechnology that acts as a catalyst to speed up the process and triple biogas production.”
New business opportunities in biogas
Okudoh believes Africa is lagging the world in embracing this source of virtually free power: “Smart people will start investing in it now. India and China are going big on these small-scale bioenergy plants, which are delivering a return on investment in less than five years.
“The digested effluent (digestate) after the whole process is completed is proving almost more valuable than the power itself, with protein for pet foods and the digestate touted as better quality than commercial fertiliser – so these present new business opportunities for biogas entrepreneurs,” he says.
Okudoh believes this completes the loop.
“If you invest the money in bioenergy generation, you’ll get it back. Soon, even waste itself will become a source of revenue. If consumers don’t have enough waste available to generate the power they need, they will start buying waste and the price of waste will rise.
“For farmers, the sale of waste, or moving into biogas production themselves, offer opportunities to lower their production costs, reduce waste, and generate additional revenue.”
This is decentralised energy power production that is a win for every stakeholder, he adds. “If each village or community puts waste together to generate power, they will also be cleaning the area, avoiding diseases and vermin, and saving the planet. I believe this is the future for communities across Africa.”
Okudoh contributed to the technical report on The State of Waste to Energy Research in South Africa in 2014, which was published by SA DoE Renewable Energy Centre for Research and Development (RECORD), and in 2015 he published a book titled “Biogas Production in Africa: Benefit Potentials of Cassava Biomass.”
On the importance of credible research information, he says: “It is critical to my survival as an academic. It allows me to compare and evaluate published data to gain a full understanding of my research area and the biotech industry. It also helps me to prepare for all potential risks that might occur in my planned future research. Good research information improves my decision making, enhances my efficiency and provides me with a competitive edge over my peers.”
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