The Tropenhaus in Frutigen, Switzerland, is a commercial project using geothermal energy from hot water flowing out of the Lötschberg base tunnel for the production of sturgeon meat, and caviar and formerly exotic fruit in a tropical greenhouse in the Swiss alps.[1] In 2007, the project received the Prix Evenir, the Swiss petroleum industry's CHF 50,000 award for sustainable development.[2]
The idea for the greenhouse began in 2002 when it became apparent that the water continuously flowing out of the Lötschberg Base Tunnel[3] could not be directly diverted to the local river, the Kander, as its temperature of 20 °C would disrupt the biological rhythm of the endangered trout there.[1] Rather than cooling the water artificially, wasting its thermal energy, tunnel engineers founded a start-up company to use the warm water to heat a greenhouse. The construction of the site began in May 2008 at 8 million CHF, and was completed by the end of 2009.