A runner taking part in the 38th Annual Empire State Building Run-Up is pictured arriving on the 86th floor in the Manhattan borough of New York February 4, 2015. (Photo by Carlo Allegri/Reuters)

The Empire State Building towers over the Manhattan skyline as tourists gather on the observation deck of Rockefeller Center on February 13, 2012 in New York City. The owner of the Empire State Building, Malkin Holdings, plans to raise up to $1 billion in an initial public offering on the 102 story Manhattan landmark. (Photo by John Moore/Getty Images)

Members of Brazil's Movimento dos Sem-Teto (Roofless Movement) stand in the hallway of one of the 11 empty buildings that the movement took over recently, in the centre of Sao Paulo, November 6, 2012. According to City Hall, there are some 400,000 people in need of stable housing, including the 4,000 families of the Roofless Movement who are squatting in abandoned or vacant buildings that range from apartment blocks to hotels, in Sao Paulo, the largest city in South America. (Photo by Nacho Doce/Reuters)

A general view of atmosphere at the annual VOLT Festival in Sopron, 208 kms west of Budapest, Hungary on June 30, 2017. (Photo by Sandor Csudai/Rockstar Photographers)

A general view of atmosphere at the annual VOLT Festival in Sopron, 208 kms west of Budapest, Hungary on August 16, 2016. (Photo by Mudra László/Rockstar Photographers)

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 general view of atmosphere at the annual VOLT Festival in Sopron, 208 kms west of Budapest, Hungary on August 16, 2016. (Photo by Rockstar Photographers)

A general view of atmosphere at the annual VOLT Festival in Sopron, 208 kms west of Budapest, Hungary on June 26, 2017. (Photo by Mudra László/Rockstar Photographers)