Top: Turnstiles equipped with prototype mini turbines at Paris metro station. Photo by Tdorante10, CC BY-SA 4.0 DEED, via Wikimedia Commons (cropped and manipulated by BioCycle)

A pilot project in the summer of 2023 at the Miromesnil Metro Station in Paris converted six turnstiles into prototype mini turbines — essentially underground wind turbines. The turbines, supplied by Iberdrola SA, a Spanish energy company, capture continuous kinetic energy from very small movements. For two days, 27,000 passengers going through the turnstiles yielded 2,000 watts/day of energy. If the mini turbines were installed across the city’s Metro network, they could produce 136 megawatts a year from the 4.5 million commuters, saving 30,000 tons of carbon dioxide, according to Iberdrola SA. Notes a Bloomberg News article on the pilot, “an upgrade across the metro system won’t happen anytime soon since it’s deemed too expensive, but the trial is an indication of emerging climate ideas.” The article notes that Iberdrola partnered with students at French engineering school Junia to design and install the mini turbines for the pilot project. The students are now working on developing more viable future iterations of the technology that can be used in metro stations in cities around the globe.