Environmental Engineering Reference
In-Depth Information
Fig. 10.12 illustrates variations of the essential variables determining the heat
production costs, using the example of a new deep well designed for supply pur-
pose SFH-II (Chapter 1.3). The figure shows that the full load hours and the am-
ortisation period have a great impact on the heat production costs. But also opera-
tion and fuel costs as well as total investment costs greatly influence the heat pro-
duction costs.
56
Overall investment
(6.95 Mio. € = 100 %)
54
Depreciation period
(22 years = 100 %)
52
50
Interest rate
(4.5 % = 100 %)
48
Fuel price
(12 €/
GJ = 1
00 %)
46
Electricity price
(0.15 €/kWh = 100 %)
44
42
Operation costs
(160 k€ = 100%)
70
80
90
100
110
120
130
Parameter variation in %
Fig. 10.12
Variations of parameters of the heat supply by a geothermal deep well (new
well according to demand scenario SFH-II, house substations not varied; see Table 10.3)
Environmental analysis.
Additionally, the analysed reference plants designed for
geothermal energy utilisation by means of deep wells are assessed according to
selected environmental aspects which are discussed in detail throughout the fol-
lowing paragraphs. These environmental effects are subdivided into effects caused
during plant construction, operation, malfunctions, and at the end of the operation
(i.e. demolition).
Construction.
During the construction of deep well systems environmental effects
are mainly caused during the drilling of the well due to e.g. uncontrolled drilling
through two or several aquifers of different pressure levels, penetration of harmful
substances into the underground caused by drilling operations, drill pipes and
accessories or chemical-biological modifications due to drilling fluids. However,
these effects can almost be entirely avoided if the corresponding legal guidelines
are taken into consideration. During the construction phase noise emissions may
occur which are restricted to this period only. This is also true for the usage of the
area around the drilling location.
Operation.
The site-specific environmental effects caused by geothermal deep
well systems are comparable to those of every other kind of heat supply plant.
However, since heat is partly provided by geothermal resources that are almost
free of any emission released during operation, and which substitute fossil fuel
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