Zimbabwe Teen Illuminates Rural Homes With Electricity From Household Waste

People in rural Zimbabwe "are living most of their lives in darkness."

Macdonald Chirara

There isn’t much to do at night in the rural parts of Zimbabwe, where high school senior Macdonald Chirara visits his grandmother during the holidays. While a city kid might watch Netflix or read a novel by lamplight, that simply isn’t an option in those remote communities. Chirara, whose invention of a sustainably powered biogas digester has taken the global science fair community by storm, says that when it gets dark there, it usually stays dark.

“During my stay at the rural areas we usually slept early because there was no lighting or any form of entertainment,” the Zimbabwe Republic Police High School student tells Inverse. “I sometimes experienced the challenges wrought by looking for firewood in bushes.“

In the urban parts of Zimbabwe, electrification has reached 80 percent. But in the rural areas, that number dwindles to 20 percent. Chirara has watched his grandmother and her neighbors collect and burn firewood for cooking and illuminating the night, a system that was been passed down “from generation to generation” until it became the norm. He invents in the hope that future Zimbabweans will have more options.

Macdonald Chirara
Chirara with his parents and school headmaster.

“What touched me most was how most people in the rural areas of Zimbabwe are living most of their lives in darkness,” he says. With a clear goal in mind and a sense of scientific curiosity sparked at least in part by Carl Sagan, he set to work building and testing a biogas digester that breaks down organic waste into useable electricity using bacteria collected from local plants.

The digester is ingenious in its resourcefulness. It’s well established that methane gas can be burned to generate power, but what’s less often explored is the idea that methane doesn’t have to be extracted from deep underground chambers. Chirara understood that organic waste like potato peels and cow dung could be broken down into methane gas, if only the right catalyst was available. Fortunately, Chirara was also well aware that the catalyst was all around him.

macdonald chirara invention
A prototype of Chirara's biodigester.

Carpets of water hyacinths, leafy aquatic plants with deceptively pretty flowers, blanket the surface of ponds and lakes in Zimbabwe, suffocating them of oxygen. “It is one of the most noxious weeds and many attempts have been made to eliminate or control it,” says Chirara. Part of the reason the invasive plant is such an efficient colonizer is because it’s an opportunist, using the native bacteria in the water to support its growth. “Among the microbial populations are methanogen bacteria, microorganisms that produce methane as a metabolic by-product in anoxic conditions,” explains Chirara, who seized the opportunity to put the plants to far more useful work.

With the support of a science teacher named Mr. Ngomanyuni, who Chirara credits for his understanding of the scientific method, the biogas digester came into being. Growing water hyacinths in a slurry of organic waste and water, he diverted the newly formed methane gas into a thermoelectric generator, which measured a maximum of 1.5 volts — about the same as a standard AAA battery. If scaled up, it could provide enough power to light a home or sustain a flame for cooking without the hassle and environmental consequences of collecting and burning firewood.

common water hyacinth
Chirara put the water hyacinths to good use. 

In early 2018, Chirara won the Community Innovation Award from the US-based Society for Science & the Public with his invention, which led him to the Intel International Science and Engineering Fair in May. There, competing against student scientists from all over the world, he placed fourth in Physical Sciences, taking home a $500 prize.

Back in Zimbabwe, he’s already hard at work on a new project: a solar water pumping system to replace the tedious hand-cranked pumps that so many people are reliant on. Like the best enterprising millennials, he’s also hoping to establish a startup called Everlasting Technology, a sustainable energy provider with a focus on bioenergy. Once again, his work centers around making do with what little is available — instead of water hyacinths, this time he’s using sunlight — to make life easier for the people around him.

“Most basic needs are met with difficulty in rural areas of Zimbabwe and the phenomenon remains the same looking at Africa at large,” he says. “These include reliable sustainable energy, clean water and 21st century educational resources.”

An avid reader of the works of Paulo Coelho, Robin Sharma, and, of course, Sagan, Chirara hopes to continue to use science to provide “logic, sense, and order in what might otherwise seem chaotic.”

“It may not solve all of our problems,” he says. “but it usually shows us the path to the solutions.”