Energy- the ability to do work
Did you know that everything in the world can be organized into two categories or groups? These two groups are matter and energy. If something is not matter, it’s energy. Energy is all around us. We can see it as light, feel it as heat, hear it as sound, and produce it as we do work. Let’s investigate the forms of energy, the sources of energy, and how energy can be transformed and used.
Energy is the ability to do work or cause change. Work takes place when energy is transferred to an object causing it to move or change. For example, when a golfer swings a golf club, he transfers energy to the club causing it to move. The club then transfers energy to the ball causing it to roll across the green. Energy can also cause other kinds of changes in matter. For example, energy can cause liquid water to change into a gas called water vapor.
There are two basic types of energy: kinetic and potential. Kinetic energy is the energy of motion. It is energy that is “in use.” When the golfer swings his club, it has kinetic energy. As the golf ball rolls across the green, it also has kinetic energy. All moving objects have kinetic energy. Things in our natural environment, like moving water and wind, also have kinetic energy.
Potential energy is stored energy. It is energy that is not “in use” but available to do work. Even when an object is sitting still, it has energy stored inside that can be turned into kinetic energy (motion). Some potential energy is based on position. This is due to the fact that any object that can fall because of Earth’s gravitational pull has stored energy. For example, if you have two books, and you place one book on the top shelf and one book on a lower shelf, the position of the book on the top shelf causes it to have greater potential energy. Potential energy can also be found in fossil fuels like coal, petroleum, and natural gas. The chemical energy in fossil fuels is potential energy until it is released.
In addition to being stored or used, energy can also be transformed or converted from one form to another. If you have ever bounced a ball, you have witnessed a transformation of energy. As the ball is held above the ground, it has potential or stored energy. When it is released, the potential energy transforms into the kinetic energy of motion.
Some important sources of energy include fossil fuels, wood, wind, water (hydropower), the sun (solar energy), and the Earth’s interior. Fossil fuels like coal and petroleum originate from the remains of ancient plants and animals and are rich in the elements carbon and hydrogen. These remains contain stored (potential) solar energy that the plants made through the process of photosynthesis and which was then used and stored by the animals that ate the plants. The stored or potential energy in fossil fuels can be released and transformed into kinetic energy through burning. This heat or thermal energy can then be transformed into electrical energy by your local power company. As this electrical energy enters your home, it can be transformed into mechanical energy by your household appliances. Can you think of other energy transformations that occur in your home each day?
Fossil fuels are used to heat water and air, power cars and airplanes, cook our food, generate electricity, and make plastics and fertilizers. :o) Two advantages of using fossil fuels are that they produce huge amounts of electricity and are easy to transport. They can be used by power plants anywhere in the world that are connected to a transportation source. On the other hand, there are some disadvantages to using fossil fuels. :o( The burning of fossil fuels causes widespread water and air pollution, the amount of greenhouse gases in the atmosphere is increased, the mining process is dangerous, and large areas of land are destroyed through the process of strip mining. In addition, these sources of energy take very long periods of time to form and once depleted, or gone, are essentially nonrenewable.
Wood is another important source of energy. As a tree grows, solar energy is stored in its cells. When wood is burned this potential energy is released as heat. Wood is one of the world’s most important forms of nonfossil energy.
Almost half of the wood harvested each year on Earth is used for fuel. This is especially true in less industrialized nations where people rely, or depend heavily on wood for heating their homes and cooking. :o) One advantage of using wood and other forms of biomass like tree branches, yard clippings, left-over crops, and wood chips, bark, and sawdust from lumber mills is that they can be replenished over relatively short periods of time. Even though they are considered to be renewable energy sources, they still need to be wisely managed. :o( One major disadvantage to burning wood or any other biomass material is the negative affect on air quality. Burning wood for energy is seen as a contributor to the buildup of green house gases in the Earth’s atmosphere. Anytime anything is burned, it makes CO2, carbon dioxide~ CO2 is a major reason for the build up of greenhouse gases.
Wind is another important source of energy. It is used all over the world and is one of the oldest forms of energy used by man. Wind is formed (created) by the heating of the Earth’s surface. As the surface of the Earth heats up, the air above the Earth heats up, becomes lighter, and begins to rise. As it rises, cooler, heavier air moves in to take its place. This movement of air creates wind.
There are a number of advantages to using wind as an energy source. :o) (1)Wind energy is easily captured by windmills or turbines and transformed into mechanical energy. It can then be used to pump water for irrigation, grind grain, or generate electricity. Wind energy is also (2) renewable and available on a perpetual, or ongoing, basis. Because it is (3) inexpensive and (4) pollution free, wind is one of the fastest growing energy sources on Earth. One :o( disadvantage is that few locations have steady winds available for use at all times,
Water is another important source of energy with many advantages. Moving water, or hydropower, has been used for centuries to turn wheels and power mills along the world’s rivers and streams. Today falling water is used to turn turbines to generate electricity. This hydroelectric energy is then sent through power lines to homes, schools and businesses. Like wind, the :o) (1) kinetic energy of water is renewable and available on a perpetual basis. It is also a (2) clean source of power that does not pollute the environment. One :o( disadvantage is that drought prone areas or areas with few water resources cannot benefit from this energy resource.
The sun is another important source of energy. In addition to the solar energy that is stored in fossil fuels, the sun constantly produces energy in the form of heat and light. Although this energy has been used for thousands of years to dry clothes and food, modern technologies have been developed to capture and use solar energy for different purposes. Giant mirrors are being used across the globe to heat tanks of water to produce steam to generate electricity. Water heated in this way can also be pumped directly to faucets in homes and businesses. Solar cells, which act like batteries, turn sunlight directly into electricity. Solar cells can be used to power calculators and telephones, heat buildings, and even run satellites that orbit the Earth. Like wind and water energy, :o) solar energy is (1) renewable and available on a perpetual basis. Although solar energy is (2) free and (3) produces no pollution, it has several disadvantages. :o( (1) It doesn’t work at night, and it can be (2) unreliable in areas that are not sunny year round. In addition, solar power stations and solar cells can be (3) very expensive to build and run.
Geothermal (geo=earth, thermal=heat) energy from inside the Earth is another important source of energy. This type of energy occurs when underground water is located near pockets of hot magma. The water is heated to boiling and escapes the Earth’s surface in the form of steam.
In some areas of the world this steam is used to generate electricity or is pumped directly into homes and businesses to provide hot water and heat. Around the world geothermal energy plants pump water into areas of underground magma to produce power. One such plant is located near San Francisco, California. Geothermal energy has several advantages. :o) It
(1) does not pollute the environment, and power plants using this type of energy are (2) relatively inexpensive to operate. In addition, geothermal energy is (3) renewable and available on a perpetual basis. As with other forms of energy, geothermal power has a disadvantage. :o( (1) Geothermal plants cannot be located everywhere. They require areas where magma comes close to the Earth’s surface and surface rocks allow drilling.
Another source of energy can be found in the tidal movements of our oceans. New technologies are being developed to transform the kinetic energy of ocean waves and tides into electricity. This type of energy is promising because it is :o) (1)clean, (2) renewable, and (3) more dependable than wind and solar energy sources. Resembling underwater wind turbines, many of these new tidal energy systems harness, or control, the continuous movement of ocean waves and tidal currents. Can you think of any disadvantages this type of energy resource might have? :o( (1) need to live near an ocean
Throughout this study of energy we have witnessed how energy is often transformed or converted from one form to another (never created or destroyed). A good example occurs in the formation and burning of fossils fuels such as coal. The ancient plants and animals that make up fossil fuels used solar energy to produce food and grow when they were alive. This solar energy was stored in their cells in the form of chemical energy. When fossil fuels are burned, this chemical energy is transformed or converted into heat energy. This heat energy can then be used to produce mechanical energy to run machines or produce electricity. Electric energy can then be turned into light energy. Hey, isn’t that where this whole cycle started? In short, most forms of energy can be transformed into other forms of energy. Can you describe some other energy transformations that occur around you every day?
Since its birth as a nation over 200 years ago, the use of energy in the United States has changed dramatically. In 1776, muscle power and fuel wood were the most commonly used energy sources. In addition, water powered mills ground grain for bread and wind power enabled ships to transport goods and passengers from place to place. Over the next 100 years, coal began to emerge as a common energy source. Coal-fired furnaces came on the scene and coal-powered locomotives criss-crossed the country. During the early 1900s, the use of petroleum expanded with the discovery of oil fields in the western United States. After WWII, natural gas began to be used to heat homes, and gasoline powered cars and trucks began to replace coal-fired locomotives. As the demand for electricity expanded, however, the demand for coal increased once again to run electric power plants across the country.
In today’s world, modern industrial societies are more and more dependent upon energy and the major sources of energy, fossil fuels. This dependence on fossil fuels has created new problems worldwide. In the United States, our need for energy has surpassed our production of energy. Because of this we are more and more dependent on the energy reserves of foreign nations. How would an unanticipated or unexpected energy shortage impact your country, your state, your community, and you?