Chapter 24. Chapter 24: Sun, Wind, and Water Energy
How do wind and solar power technologies capture energy?
Guiding Question 24.2
How do wind and solar power technologies capture energy? What are the advantages and disadvantages of wind and solar power, and how does each compare to fossil fuels in terms of true costs?
Why You Should Care
We have already learned that energy cannot be created or destroyed, but it can be transferred and transformed. Solar energy reaches earth as electromagnetic radiation; part of this radiation we can detect, or see, as light, but other wavelengths include infrared, or radiant heat, and different forms of ionizing radiation like ultraviolet. We can capture the heat from solar energy passively through designing buildings to be warmed by the Sun or actively through solar water heaters. Photovoltaic cells, or solar panels, use the photons in light to create an electric current. The heat from solar energy creates convective currents in the atmosphere, or wind, and we can harness this kinetic energy from the wind by using windmills. Traditionally, windmills were used to provide kinetic energy, but now we are using them widely to create electricity.
Although solar and wind power are much cleaner to use than fossil fuels, they aren’t without drawbacks. Some people object to the look of windmills on the horizon or solar panels on roofs. Neither solar or wind power are constant, so there has to be a way to store energy or a backup energy source for nights, cloudy days, and days with little wind. Probably the biggest deterrent to adopting solar and wind power is cost. The startup costs for installing personal or public solar or wind energy systems are high, prohibitively so for many people. But, if one figures in all of the hidden costs associated with using fossil fuels—acid precipitation, smog, global climate change, and groundwater pollution are just a few—it’s definitely worth using sustainable energy sources.
Test Your Vocabulary
Choose the correct term for each of the following definitions:
| Term | Definition |
|---|---|
| Also called solar cells, PV cells convert solar energy directly into electricity. | |
| The use of mechanical equipment to capture, convert, and sometimes concentrate solar energy into a more usable form. | |
| An active technology that captures solar energy for heating. | |
| The capture of solar energy (heat or light) without any electronic or mechanical assistance. | |
| Energy harnessed from the Sun in the form of heat or light. |
1.
All of the following are reasons wind turbine use has been opposed EXCEPT:
| A. |
| B. |
| C. |
| D. |
4.
For each of the components of a wind turbine listed below, write a short description of what it does in the process of producing electricity. Make sure to think about how energy is transformed in the process.
1) Blade or airfoil:
2) Shaft:
3) Gear box:
4) Generator:
2) The shaft transfers the kinetic energy of the blades to the gear box.
3) The gear box increases the rotation speed of the shaft.
4) The generator uses the increased speed from the gears to convert kinetic energy into electricity.
5.
What is the CORRECT order of the steps used to generate electricity in a wind turbine?
I. Spinning generator produces electrical current
II. Rotating blades turn shaft inside turbine
III. Wind turns turbine blades
IV. Shaft is attached to a higher-speed gear that turns generator
| A. |
| B. |
| C. |
| D. |
The following questions refer to the labeled parts of the diagram above:
10.
The arrow at 1 represents the angle of sunlight striking the house during ________, whereas the arrow at 2 represents the angle during __________.
| A. |
| B. |
| C. |
| D. |
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