Utilisation of Geothermal Energy - Renewable Energy: Technology, Economics and Environment - page 490

costs for exclusive power generation amount to about 0.17 €/kWh (for ORC with
water cooling and Kalina cycle at 180 °C or for the combined Flash process/ORC
between 200 and 230 °C).

Flas h

0.50

Double Flas h

0.45

Flash - ORC

0.40

ORC (w ater
cooled)
Kalina

0.35

0.30

0.25

0.20

0.15

0.10

Temperature in °C

Fig. 10.23 Electricity generation costs under average geological conditions (Plant A, vary-
ing temperatures, 100 m 3 /h production volume)

Electricity generation costs are further reduced by increasing the volume flow
per two-well system up to a rate of, for example, 200 m 3 /h. Under favourable site
conditions minimum production costs for exclusive power generation amount to
about 0.08 €/kWh (for ORC with water cooling and Kalina process at 180 °C or
for the combined Flash process/ORC between 200 and 230 °C). But also pure
flash processes are appropriate to generate power at a price of 0.09 or 0.10 €/kWh
at a geothermal fluid temperature of approximately 220 °C.
If heat can be sold at the plant gate (Plant B), power production costs are de-
creased to 0.18 €/kWh, under average site conditions, and to approximately
0.14 €/kWh for sites with promising geothermal conditions. Although investment
costs are slightly increased when compared to exclusive power generation, the
additional heat credits allocated to the provided electricity tremendously reduce
the corresponding electricity production costs. This is due to the assumed condi-
tions of heat purchase which do not influence potential power supply. Hence,
additional heat credits are obtained at very low extra costs which in turn tremen-
dously reduce power production costs.
Electricity production costs are mainly influenced by investment costs and tem-
perature (Fig. 10.24). If, for instance, investment costs are reduced by 30 %,
power production costs are decreased from 0.17 to 0.13 €/kWh and thus by
0.04 €/kWh.