Environmental Engineering Reference
In-Depth Information
shift-operation) and/or the geothermal fluid can be used (partly) as a raw material
(like for the production of mineral water or spa purposes).
Geothermal heating stations are operated in base load. To achieve an optimum
performance of thermal capacity the goal is always to achieve a high amount of
full load hours. Furthermore, to be energetically most efficient, geothermal heat
should be directly transferred from the geothermal fluid to the heating water used
within the district heating system. Due to temperatures of the geothermal fluid
between 40 and 80 °C, in general, the return temperatures from the district heating
system should be below 40 °C. Only in case of lower temperatures, heat pumps
should be applied for additional cooling of geothermal fluid.
Fig. 10.8 shows some examples of geothermal heating stations that provide
base and peak load in a cost-efficient way. According to this, the plants may con-
sist of one or several heat exchangers for direct heat transfer. Optionally, heat
pumps may be integrated within the overall system depending on the geothermal
fluid temperatures. In this case, absorption heat pumps, electric heat pumps, and
compression heat pumps equipped with gas motors (see Chapter 9.2) may be used.
The technology to be applied is determined by the given site-specific circum-
stances, the prices for fossil fuel energy, as well as the site-specific relation of
prices between electricity and fuel.
District heating
syste m
District heating
syste m
District heating
syste m
Peak load boiler
Peak load boiler
Peak load boiler
Heat pump
CHP station
Hea t pump
Heat
exchanger
Filter
Filter
He at
exch.
Heat
exchanger
Heat
exchanger
Filter
Filter
Filter
Filter
Production
well
Production
well
Production
well
Injection
well
Injection
well
Injection
well
Direct heat exchange
Direct heat exchange and
additional cooling by
another heat exchanger
Direct heat exchange and
return flow cooling by heat
pump
Fig. 10.8 Examples of operating principles of geothermal heating stations (see /10-2/)
Currently, boiler-driven absorption heat pumps are preferred as the boiler may
be dimensioned cost-effectively also as a peak load boiler. The boiler can thus
realise heat provision in case of a malfunction of the geothermal fluid circuit.
Many geothermal heating stations are equipped with a combined heat and
power (CHP) station. Such systems cover the electricity demand for geothermal
 
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