Power And Energy Requirements

In Chapter 2 we described the difference between work, energy, and power. This chapter will deal with two of these quantities: how much power is needed, and how long is this power required. This is the same as asking how much energy is needed.

As we stated in Chapter 1, the entire process of selecting a suitable wind system involves determining what power is available from the wind at your site, knowing what you need in the way of energy and power, and then matching these to arrive at a wind system that will do the job. We will break this discussion of power and energy requirements into two separate parts. The first will discuss electric load estimation, and the second will discuss mechanical load estimation, particularly for water pumping.

Before the discussion of power requirements, let us keep in mind that while it is well to calculate how much power you need, some consideration must be given to losses, or inefficiency. That is, if you figure how much electric power you need to run a light bulb, it will take a little extra, over and above the amount needed by the light bulb alone. The wires running from the generator to the light will waste some power because of electrical resistance. Friction is another example of inefficiency. This waste ends up as a power loss in the form of heat. Estimation of losses is an important part of your calculation of your power and energy needs.

A pictorial view of energy and losses is shown in Figure 4-1. The smaller the pie slice representing loss, the more energy available to the user.

Renewable Energy 101

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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