Environmental Engineering Reference
In-Depth Information
492
utable to the ORC plant, the geothermal fluid circuit, miscellaneous and operation
costs.
0.24
0.24
0.22
0.22
0.20
0.20
Credit for district heating
A nteil Wärmegutschrif t
Power generation costs
0.18
0.18
Fuel costs
Fuel costs
Costs for personnel
0.16
0.16
0.14
0.14
Costs for maintenance
0.12
0.12
District heating system
Thermal water cycle
ORC plant
Wells
Planning
0.10
0.10
0.08
0.08
0.06
0.06
0.04
0.04
0.02
0.02
0.00
0.00
A
A
A
A
B
B
B
B
A
A
A
A
B
B
B
B
Average conditions
Average conditions
Norddeutschland
Norddeutschland
Favourable conditions
Favourable conditions
Oberrheingraben
Oberrheingraben
Fig. 10.22
Electricity generation costs of reference Plants A and B (the total costs indi-
cated by the left bars refer to the costs related exclusively to the power generation (i.e. total
power production costs of the entire plant without a possible income by heat sale through
the district heating system to the household customers), whereas the right bars consider
such a possible heat credit (and thus indicate the net power production costs))
Power production costs are considerably influenced by the temperature of the
extracted geothermal fluid. Fig. 10.23 shows this effect using the example of ex-
clusive geothermal power generation under the average site conditions. Under
such circumstances, by means of the combined ORC/flash process and an ap-
proximate geothermal fluid temperature of 200 °C minimum power production
costs amount to approximately 0.18 €/kWh. Compared to this, due to their lower
efficiencies single or double flash processes only allow to yield lower power
quantities at the same drilling costs. The specific electricity generation costs are
thus considerably higher.
The illustration shows that the specific power generation costs increase with
further increasing temperatures. This is mainly due to the influence of the well
depth on the drilling costs because the temperature can only be increased with an
increased well depth. The impact of increasing temperature on the efficiency of
the respective cycle (and thus on the achievable power output) is more than com-
pensated by the superproportional increase of drilling costs with increasing
depths.
Electricity generation costs are considerably reduced if the geothermal power
plant is located on a temperature anomaly (i.e. the increase of the temperature
with increasing depth exceeds the average geothermal temperature gradient). If a
well does not need to be drilled as deep to achieve a given temperature, produc-
tion costs may decrease considerably, since drilling costs have a major impact on
the specific energy production costs. In the present case, minimum production
Search WWH ::
Custom Search