# Costs for a wind power plant

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The investment costs of wind power plants have also decreased during the past

few years. On one hand, costs for wind power plants with the same capacity have decreased. On the other hand, the rated power of wind turbines has grown rapidly during the same time. This reduces the incidental expenses per kilowatt. Figure 6.2 shows the sale prices and rated powers of wind turbines in two different years. However, the price conditions vary between different turbine designs.

Besides the pure cost of the wind turbine, investment costs include costs for planning, installation, foundations, mains connection and transport. These costs are only partly included in the values of Figure 6.2. These incidental expenses are on average 34.5 per cent of the wind turbine sale price, but can be much higher for smaller systems. Operating costs consists of land rent, maintenance, repair and insurance costs.

The total investment cost for a wind turbine in the 1.5 MW range is currently between €1000/kW and €1600/kW depending on the site and the required infrastructure expenses. Using €1200/kW for a 1.5-MW turbine, the investment cost A0 is €1,800,000. The annual operating costs are usually between 2 and 3 per cent of the investment costs, so annual operating costs Ai of about €50,000 must be considered.

A 1.5 MW turbine at a site with a wind speed of just under 7 m/s at hub height, corresponding to 4.5 m/s at 10 m, can generate about Ea = 3.5 million kWh per year. Assuming an operating period of 20 years for the wind turbine, the calculations become:

Ctot = A0 + 20 • Ai = €1,800,000 + 20 • €50,000 = €2,800,000

Table 6.3 Annual Energy Gain for Wind Power Plants of Different Sizes and Different Wind Speeds vhub

System size

Annual energy gain in MWhJa

Table 6.3 Annual Energy Gain for Wind Power Plants of Different Sizes and Different Wind Speeds vhub

System size

Annual energy gain in MWhJa

 Rotor Power (kW) vhub = 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.