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Maitreyee Sanjiv Marathe with the e-Little Free Library
May 23, 2022

Solar Little Free Libraries provide power to people who need it most

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For many people who are homeless or members of underserved populations, cell phones are a lifeline; a phone may be their only way to keep in touch with distant friends and relatives, schedule medical appointments and job interviews, and deal with emergencies. Yet there are very few free public charging outlets available, especially outside of traditional business hours—meaning these vulnerable populations could go for long stretches with dead batteries.

That’s why a unique Little Free Library erected in Lisa Link Peace Park, a small gathering space on State Street in Madison, Wisconsin, proved popular. The kiosk, developed by University of Wisconsin-Madison engineering students, was attached to a light post in the popular shopping area and topped with solar panels. It contained a lithium-ion storage battery and multi-tipped charging cables, as well as a nice selection of books, allowing people to top off their phones 24 hours a day.

The concept for the e-Little Free Library, as the project is called, originally came from the Great Lakes Community Conservation Corps in Racine, Wisconsin, an organization that supports sustainability projects and trains and educates disadvantaged people. Its staff noticed that many homeless veterans came in specifically to charge their phones. So the organization applied for and received a grant from the Wisconsin Office of Energy Innovation to develop a scalable charging solution.

In summer 2021, the Conservation Corps contacted Giri Venkataramanan, a professor of electrical and computer engineering at UW-Madison and an expert on energy resilience and microgrids, for technical assistance. Venkataraman and PhD student Maitreyee Sanjiv Marathe took on the challenge, even organizing a hackathon at the UW-Madison makerspace they dubbed the Solympics, to generate ideas for a solar-powered charging station. The winning concept was the e-Little Free Library.

“The reason the Great Lakes Community Conservation Corps and the rest of the judges chose that is because Little Free Libraries are ubiquitous, and they blend in with the environment quite well,” says Marathe. “And you know, they’re kind of cute.”

Marathe decided to make the project the capstone for her Energy Analysis and Policy Doctoral Minor and gathered a team including other students from the program as well as interested undergraduates. The students interviewed city managers, staff at homeless shelters and people in Madison’s homeless population to understand their energy needs. They also analyzed the potential cost of the project and ways they could scale up these kiosks and spread them to other cities.

To create prototypes, Marathe teamed up in the UW-Madison makerspace with industrial systems and engineering PhD student Rebecca Alcock. The pair modified kiosks donated by the nonprofit Little Free Library organization. Alcock designed a weatherproof housing, while Marathe took care of the electronics. “I would not say the electronics were super complicated or innovative technology,” she says. “But it was a very cool engineering problem and required a good amount of effort. Especially the mounting—we had very limited experience mounting a 200-pound object on a pole!”

In mid-March 2022, ECE sophomore and team member Savannah Ahnen helped install the first prototype at the Great Lakes Conservation Corps offices in her hometown of Racine. Then, in the first week of April, after receiving permission from the City of Madison, Marathe and the team installed the State Street prototype, which included door sensors and data trackers so they could keep tabs on its usage. Over the course of several weeks, the data showed the kiosk was being used regularly to charge phones (and the books were popular too).

Marathe’s involvement in the project ended in May 2022, when the prototype was removed from the park, but other students have shown interest in continuing and expanding the e-Little Free Library project, perhaps adding WiFi and security features to the next versions. The Conservation Corps and a Madison homeless shelter are also interested in sponsoring kiosks, and the Madison City Council is considering changes that would pave the way for more public kiosk installations.

“It is rare that you can see tangible, real action happening within a semester or within a year of starting a project,” Marathe says. “But we have a prototype up on State Street, and people are considering changing zoning codes for us so the project can expand. In a way, it’s surreal and unbelievable. And I’m very grateful to the entire team.”