GMAS Informational Writing Practice

Source 1 Renewable Energy

An energy source that does not get used up is called renewable energy. The wind, the sun and heat from the Earth are sources of renewable energy.

Solar Energy

Solar energy comes from the sun. Active solar energy uses special technology to capture the sun's rays. The two types are photovoltaic cells and mirrors. They focus sunlight in a specific spot to generate electricity. PV cells last for a long time and are efficient. Passive solar energy does not use equipment. Energy comes from the way sunlight naturally changes throughout the day. One example is building a house such that it faces the sun more often and thus gets more heat from it.

There are reasons why solar power cannot be used as the only power source in a community. It can be expensive to install PV cells or build a building using passive solar technology. Also, sunshine is hard to predict. The sun can get blocked by clouds. Different places get different amounts of sunlight based on the location, time of year and time of day.

Wind Energy

Throughout history, people have been harnessing the wind's energy. Ancient Egyptians made boats powered by the wind more than 5,000 years ago. In 200 B.C., people used windmills to grind grain in the Middle East and pump water in China.

Today, we capture the wind's energy with wind turbines. These are large towers with two or three blades at the top. The wind turns the blades, and the blades turn a generator located inside the tower. This creates electricity.

Groups of wind turbines are known as wind farms. Wind farms can be found near farmland, in narrow mountain passes and even in the ocean. Wind turbines anchored in the ocean are called offshore wind farms.

Steady winds can provide cheap, reliable electricity. Turbines do not emit pollutants into the air. But wind speed changes constantly, depending on the time of day, weather and geographic location. They are also dangerous for bats and birds, as they can crash into them.

Hydroelectric Energy

Hydroelectric energy is made by flowing water. Most hydroelectric power plants are located on large dams, which control the flow of a river.

Dams block the river and create an artificial lake, or reservoir. A controlled amount of water is forced through tunnels in the dam. As water flows through the tunnels, it turns huge turbines and generates electricity.

Hydroelectric energy is inexpensive and reliable. Water is constantly flowing, so the dam does not depend on the weather and time of day.

However, hydroelectric power plants are damaging to the environment. When a river is dammed, it creates a large lake behind the dam. This lake drowns the original river habitat and sometimes drowns entire towns. Silt, or dirt from a riverbed, can build up behind the dam. It can damage the dam, shortening its life span.