The school's outdoor latrines overflowed into the local water supply.
Understandably, this made some people quite upset. But Mwasaru saw this as an opportunity to turn something revolting into a revolution.
If he could redirect the overflowing human waste, it could give them cleaner water and help the school save money on fire and electricity.
See, at that same time, his school was spending a lot of money on firewood, which, like many Kenyan buildings, it used to fuel its kitchens, heat, and lights. It can be labor intensive to gather all that wood — and it's even more expensive to buy it. Plus, all the soot and ash it creates is not good for the staff to consume on such a regular and large-scale basis.
So Mwasaru thought — why not use a biogas digester instead?
In his sophomore year biology class, he had learned how these digesters can harvest natural bacterial byproducts, such as human waste and turn it into natural gas energy through a process called anaerobic digestion.
"I initially researched renewable energy and biogas [digesters] just to satisfy my intellectual curiosity," Mwasaru explains over email. "After a while, it became so much more than biology — there was chemistry too. It got to solving problems my local community faced, such as lack of access to affordable renewable energy."
His initial proposal was met with some level of resistance from the community. "I want to burn our poop to fuel the kitchen" isn't exactly the kind of thing anyone wants to hear from a high school student.
"That's what pushed me to make sure it came to pass, and made sure it benefited them. Sometimes it's the bad energy you get that pushes you to do stuff," Mwasaru says.
Their earliest tests began by collecting raw "fuel" in the form of cow dung, food waste, fresh cut grass, and eventually, water.
These components were then mixed together into a paste...
... that they poured into a plastic vessel — the digester itself.
The natural bacteria contained in all these ingredients was more than enough to spark the anaerobic process as it broke down the organic waste materials.
Over time, the dense physical waste drops down to the bottom of the container, separating from the bacteria's combustible gas byproduct, which can then be collected and used for energy.
Granted, there were a few hiccups along the way. "I have to credit the failures we have had," Mwasaru says. "Our very first bio-digester prototype had too much gas and exploded, so we had to re-learn and re-invent the model until it was stable."
See this video here of how his small-scale prototype worked here:
It demonstrated the basic way that the anaerobic process could be contained within a single plastic vessel with pipes to move the gas along, while directing all the other organic waste into the ground. It wasn't enough to power the entire school on its own, but it was a start.
Then, at the startup camp, the teens had the opportunity to work alongside student engineers from MIT to hone and refine their project.
In fact, the product that this high schooler devised was so impressive that it earned them funding from Global Minimum — a charitable organization that encourages young innovators and leaders in Africa — to build a second, improved prototype.
"Leroy seeks to understand everything he doesn't know by asking probing questions, taking notes and experimenting to learn," said David Moinina Sengeh, an MIT Researcher who also serves as Global Minimum's board president, in an interview with CNN. "His curiosity to explore and learn from doing within a motivation to bring broader social change is something that we hope to see in all our youth and frankly everyone."
He also returned home to the small village where his father still lives and helped to install a biogas digester there too, using the dung from his father's six cows. It generates enough gas for him to share with the other 30 houses in the village. Plus, it made things easier for the women in the village — another cause that Mwasaru is passionate about — who were sometimes spending up to 24 hours a week collecting firewood.
"When I deployed the Biogas pilot in my rural home, I mainly envisioned it as a way of leveraging sustainable renewable energy to make the world a better place through my community," Mwasaru says. "Now I believe through our activities that other sectors [such as women empowerment] could benefit immensely from the approach."
Since graduating from Maseno School, Mwasaru has taken a gap year to focus on the company's mission to address the lack of affordable renewable energy and proper sanitation that affects some 9 million Kenyan households.
He hopes to steer the company into an impactful organization that offers a wide range of products and services, including biogas digesters. He does have plans to go to college — but for now, Greenpact is his priority.
"I didn't see myself focusing on renewable energy but after doing some work in the field I figured out that I am actually more into renewable energy than I had imagined," Mwasaru says.
Now he's determined to show the world how to turn energy into opportunity and vice versa. The only way to do that is to stop seeing things as waste and start seeing them as resources instead.