Tropic House Frutigen

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 exotic fruit, sturgeon meat, and caviar in a tropical greenhouse in the Swiss alps. In 2007, the project received the Prix Evenir, the Swiss petroleum industry's CHF 50,000 award for sustainable development.The idea for the greenhouse began in 2002 when it became apparent that the water continuously flowing out of the Lötschberg Base Tunnel 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. 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. Visitors were welcomed that same year.

Source: Wikipedia