Energy conversion

previous Wind Turbines

It is important to understand that losses are encountered during the transformation of energy during the different conversions into the final form for a given application, for example consider a wind turbine, the following conversions take place:

Kinetic energy of the oncoming air strikes the rotor blades, turning them, and hence the axial kinetic energy is turned into mechanical energy of the rotating blades.

Some of this mechanical energy is lost in the control mechanism, consisting of the gear box and brake to regulate the speed and match it with that of the generator. Some energy losses are encountered due to friction.

The shaft turning with the remaining energy will rotate in turn the generator; hence converting it’s the output into electrical energy (mechanical to electrical).

Some losses are dissipated through the mechanical connections between the turbine and the electrical generator.

Electricity is used by customers for lighting / heating or to operate electric devices such as radio, television, etc. electrical devices are designed to operate on an optimum condition; efficiency of the operation will vary depending on its use, age and maintenance.

The energy flow for a typical wind turbine is shown in Figure 1.1; can be analysed in a simple way by considering the energy flow diagram, which may look like this:

100 units of energy are stored in the incoming air as kinetic energy.

40 units are converted into rotational /mechanical energy by the blades.

35 units are transferred by the shaft; some units are absorbed by the brake and gear.

33 units are converted from mechanical into electrical energy in the electrical generator.

30 units is the net output, as 3 units are lost in voltage conversion, storage and distribution.

The final figure depends on many factors, including the type of turbine, efficiency of the control system, efficiency of the generator, and the quality of the transformer and the distribution system.

Figure 1.1 Energy conversions in a typical Wind Turbine.

From \ To	Mechanical	Electrical	Thermal	Chemical	Nuclear
Mechanical	Gear Nutcracker push mower	Electric generator	friction	x
Electrical	Electric motor	Light bulb	Electric fire	Electrolysis	Particle accelerator
Thermal	Steam turbine	Thermocouple	Heat exchanger	x	Fusion reactor
Chemical	jet engine Rocket	Battery fuel cell	Car engine Boiler	Intermediate reaction	x
Nuclear	x	x	Nuclear reactor	x	x

Table 1.1 Energy conversion matrix

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