The power of waste

Seeking alternatives: Russell Phillips, associate professor of mechanical engineering at Nelson Mandela Metropolitan University

Seeking alternatives: Russell Phillips, associate professor of mechanical engineering at Nelson Mandela Metropolitan University

Renewable energy covers a lot of ground. It’s fuel for transportation, it’s heating and cooking applications, and it’s power. For most people, the latter is the hot topic of conversation as the embattled Eskom baseload has seen cities and businesses blacked out and fed up.  There is a need for investment into renewable alternatives as fossil fuels dwindle and the impact of global warming starts to make itself felt. Fortunately, there are people paying attention and solutions are not only being investigated, but implemented.

“There have been a number of wind farms implemented in the Cape and wind is one of the rising stars of the region,” says Russell Phillips, Associate Professor in Mechanical Engineering, Nelson Mandela Metropolitan University. “I believe that over the next five to 10 years, wind is likely to become one of the biggest players, closely followed by solar power, as both can put significant power into the grid.”

The wind farm installation in Jeffreys Bay is one of the largest in South Africa and supplies around 460 000 MWh per year. It is enough, according to the company, to power more than 100 000 average South African homes.

“There is good wind in areas of Africa which can contribute to our growing electricity needs,” says Professor van Zyl, department of microbiology, University of 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 hydro Africa just isn’t in a good place. The lack of water as 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 US.

“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 industrial 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 re-use the waste while also generating energy is a win,” says Chemical Engineering and Bioenergy Professor Johan Gorgens 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 environmental 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 can complement one another really well. If we do this, we could potentially create a bio-economy which would take us into a post-fossil 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. It is also a unique resource as it can be used for power, heating and fuel,” concludes Gorgens. “If you want to save the planet then the only way forward 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.”

A breath of fresh air

There are numerous renewable resources available for us to choose from, but they all come with their own challenges and price tags. They also have their own particular use cases, challenges and benefits. For the electricity grid, wind is already being captured by farms in windy areas like the Eastern Cape, but not all areas have the wind required and storage to the grid can be complex and costly. Solar is one of the most popular solutions for energy in Africa, but the storage solutions available at present are also expensive, and not as efficient as they need to be for long-term baseload provision. Biofuels are a superb form of renewable energy, but they are more suited to agriculture or more labour-intensive activities.

“Solar and wind are efficient, but highly erratic,” says Professor van Zyl, department of microbiology, University of Stellenbosch. “Biofuels are not great for heat or electricity, but can replace fossil fuels. They also can be used to supplement agriculture and assist in job creation. The issue is that we don’t have an industry running this as yet, and it is complex, and requires extensive integration.”

South Africa can also harness the power of ocean currents, something which the Cape coastline has in abundance; landfill; industrial waste; biogas and digestion; geothermal applications and biomass. Many of these alternatives are already being investigated, some have been installed and it looks like South Africa is at least paying attention to what can solve our energy needs without the potential environmental destruction of fracking and nuclear.