African Scientist Hacks Mangosteen Rinds to Create Supercapacitors for Devices

Globally, an estimated 931 million tonnes of food are lost or wasted each year—roughly one-third of all food produced, according to South Africa’s Government Gazette (2023). If other African countries matched South Africa’s 30 percent peel ratio and 10 percent conversion efficiency, the continent—home to tens of millions of tonnes of annual fruit harvests—could generate hundreds of thousands of tonnes of peel-derived activated carbon every year. At that scale, Africa could launch a domestically owned supercapacitor industry, transforming orchards and market waste into a cornerstone of its clean-energy transition.

In South Africa, food waste remains both a challenge and an opportunity. A report by Food Loss and Waste: Facts and Futures (WWF South Africa), roughly 10 million tonnes of food are discarded annually, with fruits and vegetables accounting for 44 percent of that total. Converting just 30 percent of that produce into peel—and then yielding 10 percent activated carbon—could alone supply over 132 000 tonnes of energy-grade material for supercapacitor electrodes.

Realizing the scale of food waste inspired Dr. Vianney Kitenge—a young Congolese postdoctoral fellow at the National Research Foundation’s iThemba Laboratory for Accelerator Based Sciences in Cape Town, South Africa—to develop an innovative scientific solution for fruit waste.

In an interview with African Currents, he discussed his motivations behind developing his first prototype, and his plans for scaling up production in the coming years.

"When I started my PhD in 2021, and I had to look for a topic, but I knew that it was going to be on supercapacitor. So, after doing a browse of the different literature, I saw that there was a lot of other biomass used, such as peanut shell and potato peels. But then, when I was young, I used to have this fruit called mangosteen as my favorite. I did a research on it, and I could find that there isn't much research based on that fruit. That's actually what triggered my curiosity [...]. The fruit peel itself, it's actually a biomass. It's a source of carbon. It has about 40 to 50 percent of carbon in it without even being decomposed. And that's what makes it advantageous for the production of activated carbon [...]. Energy is important for our communities, I'll say the government and actually private sector should be together and promote this type of research so that we could now put it on a bigger scale," Dr. Kitenge noted.

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