Agriculture, household waste could aid electrification push

27th January 2023 By: Marleny Arnoldi - Deputy Editor Online

An academic from the Cape Peninsula University of Technology has identified household and agricultural waste in South Africa as a valuable source of clean energy that can be deployed in communities, complexes and individual homes at a lower cost and with a faster return on investment than solar power.

Vincent Okudoh, associate professor of biotechnology at the university’s Department of Biotechnology and Consumer Sciences, says more people globally are recognising biogas as a safe, affordable and environment-friendly source of power.

For example, small-scale bioenergy plants in China and India are delivering a return on investment in less than five years.

Additionally, he says the digested efflicent after the whole process is completed is proving almost more valuable than the power generated from the material, with protein for pet food and the digestate touted as better quality than commercial fertiliser. This presents new business opportunities for biogas entrepreneurs.

Okudoh explains that the biochemical process known as anaerobic digestion that is used to break down organic waste to produce methane, among other gases, continues to become easier to install and use in urban environments and at individual homes as sources of power.

The professor first suggested in 2014 the adoption of cassava biomass for the sub- Saharan African biogas industry to grow effectively, and has since been researching the use of nanotechnology that acts as a catalyst to speed up the process of anaerobic digestion and triple biogas production.

Okudoh states that waste itself can become a source of revenue, highlighting that if consumers do not have enough waste available to generate the power they need, they will start buying waste and, therefore, the price of waste will increase.

For farmers, the sale of waste, or moving into biogas production themselves, offers opportunities to lower their production costs and generate additional revenue.

He mentions that manure from one cow provides enough power to light a house and cook meals, while just 5 kg of food waste can produce enough gas to cook a meal, boil a kettle of water and keep the lights on.

An average cow yields about 10 kg of manure a day, which corresponds to 1 000 litres of biogas or 2.14 kWh of electricity. In turn, 1 000 litres of biomethane equals 10 kWh of electricity.

In South Africa, the average household uses about 9.4 kWh of electricity a day.

“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,” he states.