The Neustadt-Glewe Geothermal Power Plant - Practical Experience in the Reinjection of Cooled Thermal Waters into Sandstone Aquifers

Abstract

Germany has a considerable hydrogeothermal potential which is available for the environmentally sustainable and resource-saving production of heat. The example of the Neustadt-Glewe geothermal heating plant (GHP) is one more proof of the principle feasibility of energy production using deep and highly saline formation waters as heat source. Since the end of January 1995, operation of the GHP has been going on smoothly confirming the correctness of the selected technical and technological solutions. In 2003, the plant was extended by an additional cooling stage in the form of an upstream power generation unit. This paper presents the experience acquired in the exploration of the site, the planning, operation, and extension of the Neustadt-Glewe geothermal plant. 1. GEOTHERMAL RESOURCES IN GERMANY In Germany, the utilization of deep geothermal resources is based on natural geothermal reservoirs with adequate geothermal deposits on the one side, and on rocks allowing hydrogeothermal energy production only after creation of artificially fractured systems on the other side. Regarding the natural reservoirs, porous rocks and secondarily fractured or cavernous rocks are of particular interest as potentially productive horizons. Such productive horizons, bearing 40 to 120 °C hot formation waters in depths ranging from 1,000 to 3,000 m, exist in large regions of Germany (Rockel, Hoth, and Seibt, 1997).