## Comparison Of Power Costs Using Two Different Wind Turbines

All too often a WECS installation is purchased according to first cost rather than performance. Since "the cheapest windmiio. will do!" is never really an appropriate criterion, you snould understand what "the cheapest windmill" really is.

Analyze, as an example, a simple wind electric system that is used only for heating water (Fig. 5-40). Compare the two hypothetical wind turbines that were described in Chapter 5 (Wir.J-mill Power and Energy Calculations). Both are rated at 1000 watts of power, and their power curves are shown in Figure 5-19. The wind duration curve is shown in Figure 5-20. Unit A is about 5 feet in diameter and has a rated wind speed of 32 mph. It produces 95 kilowatt-hours in the month illustrated in Figure 5-21. Unit B is about 12 feet in diameter, has a 20 mph rated wind speed, and yielcs 230 kWh in the same month. For simplicity, assume you already have the necessary wire and electric water heater. Therefore, just consider the wind turbine and tower costs, plus installation. The following table shows these hypothetical cases.

Notice the difference in costs. Wind Turbine B requires a stronger tower and a somewhat higher installation cost.

If you selected solely by first cost, Wind Turbine A would be the obvious choice. However, Wind Turbine A will yield 1140 kWh/ year at your site, while the more expensive Wind Turbine B will yield 2760 kWh/year. Two more factors will be considered: maintenance cost and depreciation. Assume both machines depreciate fully to no resale value in 20 years. Also, assume that Wind Turbine A, the smaller of the two, costs \$100 per year for maintenance, while Wind Turbine B costs \$150. per year. Without considering any interest costs (covered later in this chapter), calculate the total co^t of ownership over the whole 20-year life span:

Hypothetical Initial Costs of Two Wind Turbines

## Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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