Last year Dr Smith and Alanson Sample, a researcher at the University of Washington in Seattle, powered a small humidity and temperature sensor using nothing more than the energy gleaned from a television station 4.1km (2.5 miles) away.

ECONOMIST: Monitor

Where they see magic, the locals see 90-degree heat, humidity and mosquitoes the size of small birds.

FORBES: The Home Featured in 'Field of Dreams'