Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)

A couple embrace during the start of the San Fermin festival in Pamplona, Spain July 6, 2016. Revelers from around the world kick off the festival with a messy party in the Pamplona town square, one day before the first of eight days of the running of the bulls. (Photo by Vincent West/Reuters)

Amy Rimmer, Research Engineer at Jaguar Land Rover, demonstrates the car manufacturer's Advanced Highway Assist in a Range Rover, which drives the vehicle, overtakes and can detect vehicles in the blind spot, during the first demonstrations of the UK Autodrive Project at HORIBA MIRA Proving Ground in Nuneaton, Warwickshire on Friday October 21, 2016. (Photo by Fabio De Paola/PA Wire)

A staff member sets up a ROBOTLEO robot at the Global Mobile Internet Conference (GMIC) 2017 in Beijing, China April 28, 2017. (Photo by Jason Lee/Reuters)

In advance of Fleet Week performances, the U.S. Navy Blue Angels and Team Oracle aerobatics pilot Sean D. Tucker fly over the San Francisco Bay during a photo flight on Thursday, October 5, 2017. (Photo by Noah Berger/AP Photo)

Friends (L-R) Katherine Olson, Olivia Carroll and Maron Ross take a memory during the 148th running of the Preakness Stakes at Pimlico Race Course on May 20, 2023. (Photo by Jonathan Newton/The Washington Post)

A rescue team flies on a Colombian Air Force helicopter during an earthquake emergency drill with Air Force troops from Colombia, Brazil, Ecuador, Bolivia and the United States at the Palenquero Air Force base in Puerto Salgar, Cundinamarca department, Colombia, on September 2, 2021. Air Force crews from 15 countries take part in the “Angel de los Andes” exercises, where they simulated several rescue operations in different scenarios. (Photo by Joaquin Sarmiento/AFP Photo)

Jourdan Dunn poses for photographers upon arrival at the MTV European Music Awards 2016 in Rotterdam, Netherlands, Sunday, November 6, 2016. (Photo by NIVIERE/SIPA Press/Rex Features/Shutterstock)