The OMV Project Prottes Tief 11 (PT11) is about a retooled, exploited borehole (depth: 2.243m) that is used for geothermal energy extraction. The applied process, in which the heat transfer medium circulates in a closed system, can be summarized as follows: The heat transfer medium which is brought in at the top of the borehole (in most cases water is used) is pumped down and heated up more and more by the surrounding rocks. At the bottom of the borehole the medium changes direction and is transported back to the top. At the surface the geothermal energy (saved within the medium) is delivered to a borehole heat exchanger. It gives the geothermal energy to an installed heating system and, at the same time, cools the heat transfer medium down to its initial inlet temperature. After rushing through the borehole heat exchanger the heat transfer medium is sent back to the bottom of the borehole again and the circle reproduces itself. The following chapters describe the geothermal process and the plant in Prottes. Furthermore another borehole is analyzed with regard to use its geothermal energy for the heating of a nursery.