Hudson Worthington Harr, 29

Hudson Harr is a quintessential entrepreneur known in the Gulf Coast area for his work with renewable energy. Now he’s reinvesting his profits from solar into land.

At 29, Harr has already successfully built two businesses: ReRev, which turns “gyms into power plants,” and SunQuest, a solar power company. In 2006, after borrowing $10,000 from his neighbor for parts and turning his mom’s living room into a lab, Harr discovered a way to harness electricity from fitness equipment. The technology made people working out more aware of how much energy it takes to produce a kilowatt hour, Harr says. His technology is installed in 70 university gyms around the country.