| Abstract |
Geothermal energy can deliver heat and electrical power. While there is a strong competition with other renewables (wind, water, sun) with respect to power generation, the usage of geothermal energy for heating is unique. A transformation of kinetic energy into heat usually implies large losses while solar heat is often not sufficiently available in the winter time of colder regions. Furthermore, all resources currently used for heating in the colder regions of the Earth (coal, gas, oil) are emitting substantial amounts of CO2. The challenge for geothermal energy is to deliver sufficient heat at temperatures high enough for direct heating of buildings where most people live: in the urban areas. While near-distance heating systems are a successful concept for developing areas; the supply of heat via long-distance heating systems in housing stocks is a more difficult challenge. An important advantage of geothermal energy is the possibility to install geothermal capacities even in existing building stocks, since above-ground installations are minimal and have nearly no impact on architecture or living quality. Nevertheless the geothermal heat has to be delivered to the consumer and for this district heating systems are necessary. The heat source can be replaced by geothermal energy where such systems already exist. However, we propose also the construction of completely new long-distance heating systems in urban areas for the heat delivery of numerous deep geothermal drillings. Today, long-distance heating systems have to compete on the market with other less expensive, but also by far less sustainable technologies. By seeing long-distance heating as a contribution where several generations will benefit, such a competition is obviously not meaningful (compare for instance with the building of sewerage systems or subways). Instead, political decision makers should see the sustainable benefits of geothermal energy in combination with district heating and support the development with fair subsidies; after all, besides the environmental arguments even a financially pay-back is likely, but outside of typical economical time spans. The experiences with existing installations currently available European district-heating capacities will be summarized; additionally concepts for demonstration projects are shown. The challenges of such a sustainable transformation towards a CO2-reduced heating for urban areas will be discussed. |