A mine worker is seen outside “The Progreso” gold mine near La Paz, November 13, 2014. According to local media, the president of the Central Bank of Bolivia (BCB) Marcelo Zabalaga said on Thursday that the falling price of oil and minerals in the international market will not affect the national economy. (Photo by David Mercado/Reuters)

A person sits in a chair next to the Garzweiler lignite opencast mine at the Luetzerath village near Erkelenz, Germany, Tuesday, January 10, 2023. Environmental activists were locked in a standoff with police this week around the hamlet of Luetzerath that's due to be bulldozed for the expansion of a nearby lignite mine. (Photo by Michael Probst/AP Photo)

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)