The power of waste

Bloating, wind and gas — not the digestive problems of corporate South Africa, but the renewable energy solutions of the future

pany, to power more than 100 000 average South African homes.

“There is good wind in areas of South Africa which can contribute to our growing electricity needs,” says Professor van Zyl, department o f mi c r o b i o l o g y , Uni v e r s i t y o f Stellenbosch. “Another area which can provide renewable energy is geothermal, but we’re not quite there yet, and hydro has a few applications, but they’re small.”

When it comes to hydropower South Africa just isn’t in a good place. The l a c k o f wa t e r a s a resource in itself means that this form of energy generation is limited.

Geothermal energy — using the heat created by hot water or rocks to power generators — is a viable option as a source of energy for some types of industrial processes and has a strong presence in the United States.

“Geothermal has potential, but it is not being developed, and we don’t have the relevant skills at the moment,” says Theuns Dirkse van Schalkwyk, lecturer and researcher, department of indus- trial engineering, Stellenbosch University. “A great solution which is being pursued and which has extraordinary potential is landfill, and it is one which I believe should be pushed far more aggressively.”

The advantage of capturing gasses emitted by landfill — and using the waste products themselves — is that more than one problem is solved at the same time. According to the World Bank, South Africa produces about 54 425 tonnes of trash every day. We are rated the 15th highest trash producer in the world, with the average household disposing of around 2kg a day. As pictures go, this one definitely isn’t pretty.

“The amount of waste in landfills is really scary, so to reduce and reuse the waste while also generating energy is a win,” says Chemical Engineering and Bioenergy Professor Johan Görgens from the University of Stellenbosch.

Van Schalkwyk adds: “Landfill releases gases automatically, mostly methane and carbon dioxide, along with a few other unpleasant gases. The technology for landfill hasn’t been developed properly; we could use this waste far more productively. Instead of landfill, we could have a processing plant which provides both energy and recycled goods.”

The concept is also advocated by Van Zyl, who believes that biorefineries could be the next generation solution to today’s envi- ronmental and energy problems. Refineries could process waste and plant material to create products, fuel and services in a similar vein to what Sasol does with coal.

“You shouldn’t choose just one energy solution either,” he says. “What we should aim for is a symphony of renewable energies which c a n c o mp l e me n t o n e a n o t h e r really well. If we do this, we could potentially create a bio-economy which would take us into a postfossil fuel economy where what we use can be replaced, and our planet can be managed far more sustainably.”

Over the next 10-20 years, most experts believe that wind will lead the way in terms of providing sustainable energy to the grid, but there is hope that investment into other solutions will continue to grow and change the renewable landscape — literally.

“In the Western Cape there is a big biogas project going up which uses anaerobic digestion to convert [waste] into gas and then sell it on as a power source. Biogas is also a unique resource as it can be used for power, heating and transport fuel,” concludes Görgens.

“If you want to save the planet then the only way f orward is renewable energy and over the next five to 10 years, the best option is to explore what can be done with waste, both municipal and industrial. Its potential is right there.”