Environmental Engineering Reference
In-Depth Information
Table 14.6.1
Summary of reference cases performances and economics (Franco et al., 2010; Gazzani
et al., 2012a, 2012b; Manzolini et al., 2012).
NGCC with
ASC with
NGCC
CO
2
capture
ASC
CO
2
capture
Net electric efficiency [%]
58.34
49.9
45.25
33.55
CO
2
emissions [kg
CO2
/MWh
el
]
352
41
772
104
Specific investment costs [
a
/kW
net
]
630
970
166
2556
COE [
a
/MWh]
54.1
69.1
54.8
85.5
Investment costs [
a
/MWh]
9.6
15.6
23.1
35.7
Fixed costs [
a
/MWh]
3.9
5.2
4.9
10.7
Consumables costs [
a
/MWh]
0.6
1.4
2.8
7.6
Fuel costs [
a
/MWh]
40.1
46.9
23.9
32.2
Cost of CO
2
avoided [
a
/t
CO2
]
-
48.5
-
46
trading on the market, the average value in 2012 was between 6 and 9
/t
CO2
: today,
a
CO
2
capture technologies are not economically sustainable.
The COE for fossil fuel-based plants can be split into four different cost centres:
(i) investment costs (i.e. equipment and installation costs); (ii) fixed costs (i.e. labour
and maintenance costs); (iii) consumables (i.e. water make-up and chemicals); and
(iv) fuel costs. Coal-based plants are characterized by high investment costs and low
fuel costs, which is the opposite for NGCC.
In solar plants, almost the total cost of electricity arises from investment costs
since the fuel is “free'' and labour and maintenance have a limited impact.
At current technology development rates, CSP plants have higher investment costs
than fossil fuel-based plants. Moreover, the yearly operating hours of CSP are in the
range of 2000-4000 hrs rather than 7500 hrs for fossil fuel-based plants. This is because
the energy source is not always available (there is no solar radiation during the night)
and it varies during the day even in clear sky conditions (solar radiation is much
lower in the morning than at noon). Because of the limited amount of CSP installed
worldwide, there is little information about the actual plant costs; even less informa-
tion is available for solar tower and linear Fresnel technologies which are still under
development. Another parameter affecting the cost of electricity is plant location: elec-
tricity production is almost proportional to the yearly available solar energy, which can
vary from 2100 kWh/m
2
in Seville (Spain) to 2600 kWh/m
2
in the Mohave Desert in
California (USA). Finally, plant design and storage optimal size depend on the solar
energy available throughout the year. Examples of relative COE variation as a function
of the site - Las Vegas (USA), direct normal irradiation (DNI) equal to 2600 kWh/m
2
;
Seville (Spain) and Darwin (Australia), DNI equal to 2100 kWh/m
2
- storage size and
solar multiple are shown in Figure 14.6.1 (Astolfi et al., 2011).
Observing the LCOE curves displayed in Figure 14.6.1, the best results are
obtained by the Las Vegas site, which has high storage capacity: the adoption of large
storage is necessary to limit defocusing during summer days. LCOE in Las Vegas is
equal to 139
/MWh, which is about 20% lower than the Seville plant where LCOE
is equal to 168
a
/MWh); this value is very close to the difference in terms of available
a
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