Tropenhaus Frutigen: tunnel tapped heated spring, grew bananas and sturgeon
"There's an absolutely fabulous project over in Switzerland called Tropenhaus Frutigen...a tunnel was bored directly through a giant Alpine mountain to connect two cantons to promote inter canton trade and tourism. They ran into a big problem: right in the middle of the mountain they tapped into a geothermally heated spring, and out of each end of the tunnel was flowing roughly a hundred liters per second of about 65 degrees Celsius [149 degrees Fahrenheit] water...on the one side they built a plant to remove hear from the water and to pass it into the ecosystem just at the right temperature. But on the other side was an innovative group of engineers that said, 'We are in Switzerland and we have all this hot water. What are we going to do with it? Well, duh, we're going to grow bananas!' So they built all these greenhouses and they're growing bananas. They're also growing Ceylon spices, nutmeg and papayas; and it's incredible to walk in out of that cold, brisk, clean mountain air into this sultry, seductive deep, dank scent of a subtropical greenhouse."
Bruce E. Boyers, "The Personal Side of Sustainability," Organic Connections (2013): 8