South Africa was in the middle of its worst drought since records began, and the numbers behind that drought were blunt. The country had just logged its lowest rainfall since 1904, with one year bringing in only about two-thirds of the normal average, and farmers were watching crops fail for lack of water they could not summon out of the sky.
In a suburb of Johannesburg, a Grade 11 student named Kiara Nirghin decided the problem wasn’t the sky at all. It was what farmers were doing with the water that did fall, most of which drained straight past the roots that needed it, and she thought there might be a cheap way to make the soil hold on to it longer.
The chemical hiding in the fruit bowl
Nirghin started where most science fair projects start: reading about what already existed. Commercial farms already used something called a super absorbent polymer, or SAP, a synthetic gel that can be mixed into soil to soak up water like a sponge and then release it slowly as the ground dries out.
The trouble was cost and chemistry. Industrial SAPs are built from acrylic acid and sodium hydroxide, they don’t break down in the ground, and by Nirghin’s own research they ran to roughly $2,000 or more per metric tonne, putting them out of reach for the small farmers hit hardest by the drought.
What caught her attention was the reason SAPs work at all: a long chain molecule called a polysaccharide, which is very good at grabbing and holding onto water molecules.
She went looking for a naturally occurring version of that same chain and found it sitting in her own kitchen. Orange peel, it turned out, is roughly 64 percent polysaccharide and also carries pectin, the same gelling agent that thickens jam.
She added avocado skin to the mixture for its oil content, and instead of an industrial curing process, she simply left the mixture out in the sun, letting sunlight drive the reaction that cross-linked the peel into a gel.
Forty-five days on a windowsill
The project took about 45 days of experimentation to get right, and Nirghin ran her orange peel and avocado mixture against the materials it was competing with: a commercial acrylic SAP, plus plain pectin and starch on their own.
In her comparative water absorption tests, the orange peel material held onto 76.1 percent of water, edging past the acrylic SAP’s 74.7 percent, while the pectin and starch controls trailed behind both. It wasn’t a near miss dressed up as a win.
By her own numbers, the waste-derived material actually outperformed the industrial one it was supposed to be a cheap substitute for.
The economics were just as lopsided as the chemistry. Nirghin estimated her material could be produced for somewhere between $30 and $60 per tonne, against the $2,000-plus a tonne for synthetic SAPs, putting her version at roughly a fiftieth of the price.
And unlike acrylic polymers, hers was made from something farms and juice factories already throw away, and it was fully biodegradable, meaning it could feed the soil as it broke down rather than sitting in it as plastic residue.
From a science fair table to Google’s stage
Nirghin submitted the project, titled “No More Thirsty Crops,” to the Google Science Fair, an annual global competition open to students aged 13 to 18. It first won the Community Impact Award for the Middle East and Africa, one of several regional prizes handed out before the global final.
Andrea Cohan, the fair’s program leader at the time, put the appeal of the project simply: Nirghin had found a material that wouldn’t strain a farmer’s budget in something as ordinary as orange peel, and figured out how to turn it into water storage with help from avocado skin.
Then, on September 27, 2016, at Google’s Mountain View headquarters, judges named her the fair’s grand prize winner over finalists from around the world, a win that came with a $50,000 scholarship.
For a 16-year-old whose lab was effectively her own kitchen and a sunny windowsill, it was a fairly large validation of an idea that had started with a very ordinary observation about fruit peel.
What happened after the prize
Nirghin used the scholarship money to study computer science at Stanford University, starting in 2018 and later completing a master’s degree focused on AI and human-computer interaction. Her path afterward moved away from polymers and toward artificial intelligence: she became a researcher at Stanford’s AI lab, was named to TIME’s Most Influential Teens list the year she won, joined Facebook’s tech sustainability board as an undergraduate, and became a Thiel Fellow.
She also published a book, Youth Revolution: #BeTheChange, featuring contributions from other young activists including Malala Yousafzai. In 2022 she co-founded an AI startup, Chima, with her sister.
The detail that still stands out about the original project, though, is the curing step. Every other ingredient in Nirghin’s polymer was something she scavenged from waste: peel that would have been thrown out, skin that would have gone in the compost.
But the step that turned that waste into a working water-storage gel was sunlight, the one resource South Africa had in punishing surplus during the drought.
The same relentless sun that was drying out the country’s fields was, on a Johannesburg windowsill, doing the work of curing the material meant to fight back against it.