| Title | Geological and Economic Conditions for the Utilization of Low-Enthalpy Hydrothermal Resources |
|---|---|
| Authors | Ernst Huenges, Kemal Erbas, Andrea Seibt, Peer Hoth, Kuno Schallenberg, Martin Kayser and Martin Kaltschmitt |
| Year | 2000 |
| Conference | World Geothermal Congress |
| Keywords | geothermal energy, low-enthalpy, direct use, district heating, resources, economy, environmental aspects |
| Abstract | The utilization of geothermal energy is regarded as a promising possibility to cover a substantial part of mankindís increasing energy demand. Today the role of hydrothermal resources used in Germany for low temperature heat supply is subordinated with respect to the energy demand. A more widespread application is limited by a variety of factors of different nature and scale such as regional geological conditions (supply) and consumer structures (demand). Technical solutions for the exploitation of the different resources are available, but especially geological factors are only known with some degree of uncertainty. Therefore, reliable predictions for heat generation costs are difficult to obtain. They depend on very detailed specific information on local conditions, as the technological layout is strongly affected by the above mentioned parameters and their interdependence. Within an interdisciplinary working group of geoscientists, engineers, and economists the following topics and their coupling was investigated: ï geologic-petrophysical characterisation of the resources, ï conditioning of the geothermal water cycle, ï long-term behaviour of the utilised aquifers, ï economic analysis of drilling alternatives and various design plants ï optimisation of district heating systems, and ï environmental and economic analysis. The investigations contribute to a better general understanding about mechanisms and processes during the exploitation of hydrothermal resources. Recommendations for the layout of geothermal heating plants and their operational regimes are derived. The investigations showed that geology, technology and demand are suitable for a more widespread utilisation. The technically available hydrothermal energy is approximately4 orders of magnitude higher in Germany than the present exploitation. The tools developed show, that environmental effects associated with the utilisation of fossil energy are avoided to a great extent by using geothermal energy. Therefor providing this energy alternative would reduce CO2-emissions significantly and very cost effective. For large installations heat production costs are even competitive with the fossil fuel combustion of their alternatives. As an outlook can be said that supplying a given local demand needs research to reservoir stimulation with the aim to reduce the drilling risk. |