It could just take $12 to bring electricity to homes in developing countries, thanks to a 15-year-old girl from Florida. Hannah Herbst presented the “Beacon” at the 2015 Discovery Education 3M Young Scientist Challenge, with the energy probe winning her “America’s Top Young Scientist” and $25,000. 

Herbst was inspired to create a cheap generator after corresponding with her nine-year-old pen pal in Ethiopia, who didn’t have easy access to electricity. “I can’t even imagine a day without electricity,” she said to Business Insider.  

The Beacon is made from recycled materials, including a 3D-printed propeller connected to a hydroelectric generator by a pulley inside a plastic PVC pipe. It converts water into usable electricity, an idea that came to her while boating with her family and noticing the strong current moving the boat around. An early test allowed her to power two LED lights in this manner. If the design was larger, Herbst predicted, it could power three car batteries in under an hour — exactly the amount of energy needed to power saltwater desalination pumps to produce fresh water. 

Herbst was one of nine finalists at the Discovery Education 3M Young Scientist Challenge in 2015, allowing her to be paired with a 3M scientist, Jeffrey Emslander, for a summer mentoring program. Over three months, she was able to take her invention from design to a working prototype. 

After winning the award, Herbst said she wanted to donate part of the prize money to her pen pal in Ethiopia then use the rest of the money to keep working on the device. “When I’m done developing it, I’m going to open source it. Everybody in the world can have access to the materials list and the data I got — everything you need to make this device,” she told Fast Company in 2015. Water has continued to be a valuable power source for inventions, including a water battery out of China that lasts longer than a typical lithium-on battery and Toyota’s continued hydrogen-powered vehicle efforts.

Since 2015, Hannah has won many other honors and rewards. She continued competing in science fairs, including winning the Intel International Science and Engineering Fair in 2016, 2017, and 2019. That same year, she also placed first at the Ashtavadhani Vidwan Ambati Subbaraya Chetty Foundation in the Translational Medical Sciences category. Today, she is the founder and CEO of Golden Hour Medical, a company that develops emergency devices that designed for ease of use by non-medical professionals.