Environmental Engineering Reference
In-Depth Information
According to Fig. 9.22, the heat generation costs decrease significantly with an
increased demand in heat. Additionally, in all analysed cases air-coupled systems
always show comparatively higher heat generation costs than systems with a
ground collector.
In order to give a better estimation and evaluation of the influence of the dif-
ferent parameters on the generation costs, Fig. 9.23 shows a variation of the main
cost-sensitive parameters of an 8 kW heat pump system with ground collector and
direct evaporation (GD). According to this, investments and the required heat
amounts (which correspond to the full load utilisation hours) have the main influ-
ence on the heat generation costs. It is assumed that heat capacity and thus the
costs of the heat source system do not change under the influence of heat dis-
charge variations. The duration of the amortisation period also has a significant
influence on the heat generation costs - like the SPF achieved by the system.
Electricity and operation costs and the assumed interest rate have less influence on
the heat generation costs.
45
Total Investment
11 k
€ = 10
0 %
Operating costs
40
186
€ = 1
00 %
Electricity cost
580
€ = 1
00 %
35
Depreciation rate
16.1
a = 1
00 %
30
Interest rate
4.5
% = 1
00 %
Heat demand
25
55.7
GJ
/
a =
100 %
SPF
4
=
100
%
70
80
90
100
110
120
130
Parametervariation in %
Fig. 9.23
Parameter variation of the main influencing variables on the specific heat genera-
tion costs using the example of an 8 kW heat pump system equipped with a horizontal
ground-coupled heat exchanger and direct evaporation (GD) (reference system SFH-II;
amortisation period of 16.1 years corresponds to the weighted average of all system com-
ponents; see Table 9.8 and 9.9)
9.3.2
Environmental analysis
For the systems utilising ambient air and shallow geothermal energy analysed so
far (Table 9.7) a number of selective environmental parameters are discussed be-
low occurring during construction, normal operation, in the case of an accident
and at the end of operation.
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