Environmental Engineering Reference
In-Depth Information
Table 6.3
Annual Energy Gain for Wind Power Plants of Different Sizes and
Different Wind Speeds
v
hub
System size
Annual energy gain in MWh
el
/a
Rotor
Power (kW)
v
hub
= 5 m/s
6 m/s
7 m/s
8 m/s
9 m/s
30 m
200
320
500
670
820
950
40 m
500
610
970
1360
1730
2050
55 m
1000
1150
1840
2570
3280
3920
65 m
1500
1520
2600
3750
4860
5860
80 m
2500
2380
4030
5830
7600
9220
120 m
5000
5300
9000
13,000
17,000
20,000
These costs, excluding return on capital, are close to the costs of conventional
power plants. Renewable energy sources legislative acts in Germany and Spain
guarantee a payment for wind-generated electricity of above
0.06/kWh. This
has made wind power competitive at many sites without any further subsidies
and initiated the present wind power boom.
However, at average sites with a wind speed below 5 m/s at 10 m height,
wind turbines can normally be operated economically only with grants since
the annual energy gain decreases significantly as shown in Table 6.3. The table
also shows that the energy gain relative to the power rating also increases with
the turbine size. The higher hub height of large systems is the main reason
behind this. Theoretically, small turbines can also be installed with higher hub
heights but this usually makes the economics worse. Larger system sizes also
offer the potential for future cost reduction.
€
Costs for a solar thermal system for domestic water heating
The costs for solar domestic water heating systems break down as just under a
third for the solar collector, just over a third for the hot water storage tank
and accessories and a third for the installation. In industrialized countries the
prices of flat-plate collectors are between
200/m
2
and
350/m
2
and prices of
€
€
700/m
2
. A 300 litre stainless
evacuated tube collectors are in the range of
€
steel water tank costs between
1100. Hence, the price of a
reasonable system with 4 m
2
of flat-plate collector and a 300 litre hot water
tank without installation is about
€
700 and
€
2700. The average cost for a collector
system with forced circulation used for a single household is between
€
€
3000
and
5000 including installation. If the
solar energy system is installed in a new building or if the conventional heating
system must be renewed anyway, the cost for the system can be lower. Public
subsidies can also decrease the costs. However, due to much lower labour costs
and simpler materials used for the water tank and pipes, solar collector systems
are considerably cheaper in countries such as China, Greece and Turkey. In
China, a standard collector system with a 2 m
2
vacuum tube collector and a
180 litre water tank is sold for about
€
3500 without installation and about
€
430 (ESTIF, 2003).
A common domestic solar water heating system is the basis for the
following calculations. The annual heat demand in this example is 4000
€
