Energy

 Eneregy is the ability to do work. Energy comes in different forms - heat (thermal), light (radiant), mechanical, electrical, chemical, and nuclear energy. There are two types of energy - stored (potential) energy and working (kinetic) energy. For example, the food you eat contains chemical energy, and your body stores this energy until you release it when you work or play.

All forms of energy are stored in different ways, in the energy sources that we use every day. These sources are divided into two groups - renewable (an energy source that we can use over and over again) and nonrenewable (an energy source that we are using up and cannot recreate in a short period of time). Renewable energy sources include solar energy, which comes from the sun and can be turned into electricity and heat. Wind, geothermal energy from inside the earth, biomass from plants, and hydropower from water are also renewable energy sources.

However, we get most of our energy from nonrenewable energy sources, which include the fossil fuels - oil, natural gas, and coal. They're called fossil fuels because they were formed over millions and millions of years by the action of heat from the Earth's core and pressure from rock and soil on the remains (or "fossils") of dead plants and animals. Another nonrenewable energy source is the element uranium, whose atoms we split (through a process called nuclear fission) to create heat and ultimately electricity.

Coal - A Fossil Fuel

Coal has four main uses:

• For Electric Power- Power plants burn coal to make steam. The steam turns turbines which generate electricity. Electric utility companies use over 80% of the coal mined in the United States.
• For Industry - A variety of industries use coal's heat and by-products. Separated ingredients of coal (such as methanol and ethylene) are used in making plastics, tar, synthetic fibers, fertilizers, and medicines. The concrete and paper industries also burn large amounts of coal. Industrial consumers use over six percent of the coal mined in the United States.
• For Making Steel - Coal is baked in hot furnaces to make coke, which is used to smelt iron ore into iron needed for making steel. It is the very high temperatures created from the use of coke that gives steel the strength and versatility for products such as bridges, buildings, and automobiles.
• For Export - The United States is the world's leading coal exporter. Approximately 80 million tons are exported every year to about 40 different countries worldwide. Most trade is with Western Europe, Canada and Japan.

Petroleum (Oil) - A Fossil Fuel

Oil was formed from the remains of animals and plants that lived millions of years ago in a marine (water) environment before the dinosaurs. Over the years, the remains were covered by layers of mud. Heat and pressure from these layers helped the remains turn into what we today call crude oil . The word "petroleum" means "rock oil" or "oil from the earth."

Crude oil is a smelly, yellow-to-black liquid and is usually found in underground areas called reservoirs. Scientists and engineers explore a chosen area by studying rock samples from the earth. Measurements are taken, and, if the site seems promising, drilling begins. Above the hole, a structure called a 'derrick' is built to house the tools and pipes going into the well. When finished, the drilled well will bring a steady flow of oil to the surface.

After crude oil is removed from the ground, it is sent to a refinery by pipeline, ship or barge. At a refinery, different parts of the crude oil are separated into useable petroleum products. Crude oil is measured in barrels. A 42-U.S. gallon barrel of crude oil provides slightly more than 44 gallons of petroleum products. This gain from processing the crude oil is similar to what happens to popcorn, it gets bigger after it is popped.

One barrel of crude oil, when refined, produces 19.4 gallons of finished motor gasoline, as well as other petroleum products. Most of the petroleum products are used to produce energy. For instance, many people across the United States use propane to heat their homes and fuel their cars. Other products made from petroleum include: ink, crayons, bubble gum, dishwashing liquids, deodorant, eyeglasses, records, tires, ammonia, and heart valves.

Natural Gas - A Fossil Fuel

Millions of years ago, the remains of plants and animals decayed and built up in thick layers. This decayed matter from plants and animals is called organic material - it was once alive. Over time, the mud and soil changed to rock, covered the organic material and trapped it beneath the rock. Pressure and heat changed some of this organic material into coal, some into oil (petroleum), and some into natural gas - tiny bubbles of odorless gas. The main ingredient in natural gas is methane, a gas (or compound) composed of one carbon atom and four hydrogen atoms.

Because natural gas is colorless, odorless and tasteless, mercaptan (a chemical that has a sulfur like odor) is added before distribution, to give it a distinct unpleasant odor (smells like rotten eggs). This serves as a safety device by allowing it to be detected in the atmosphere, in cases where leaks occur.

Natural gas is also an essential raw material for many common products, such as: paints , fertilizer, plastics, antifreeze, dyes, photographic film, medicines, and explosives. We also get propane, a fuel we use in many of our backyard barbecue grills, when we process natural gas.

Industry depends on it. Natural gas has thousands of uses. It's used to produce steel, glass, paper, clothing, brick, electricity and much more!

Homes use it too. More than 61 million homes use natural gas to fuel stoves, furnaces, water heaters, clothes dryers and other household appliances. It is also used to roast coffee, smoke meats, bake bread and much more.

Nuclear Energy - Energy From Atoms

A nuclear power plant operates basically the same way as a fossil fuel plant, with one difference: the source of heat. The process that produces the heat in a nuclear plant is the fissioning or splitting of uranium atoms. That heat boils water to make the steam that turns the turbine-generator, just as in a fossil fuel plant. The part of the plant where the heat is produced is called the reactor core.

Atoms are made up of three major particles: protons, neutrons and electrons. The most common fissionable atom is an isotope (the specific member of the atom's family) of uranium known as uranium-235 (U-235), which is the fuel used in most types of nuclear reactors today. Although uranium is quite common, about 100 times more common than silver, U-235 is relatively rare. Most U.S. uranium is mined, in the Western United States. Once uranium is mined the U-235 must be extracted and processed before it can be used as a fuel. In its final usable state, the nuclear fuel will be in the form of a pellet roughly one-inch-long, which can generate approximately the same amount of electricity as one ton of coal.

Renewable energy sources can be replenished in a short period of time. The five renewable sources used most often include hydropower (water), solar, wind, geothermal, and biomass.

Hydropower - Energy from Moving Water

Of the renewable energy sources that generate electricity, hydropower is the most often used. It is one of the oldest sources of energy and was used thousands of years ago to turn a paddle wheel for purposes such as grinding grain. The first U.S. hydroelectric power plant opened on the Fox River near Appleton, Wisconsin, on September 30, 1882. Until that time, coal was the only fuel used to produce electricity. Because the source of hydropower is water, hydroelectric power plants must be located on a water source. Therefore, it wasn’t until the technology to transmit electricity over long distances was developed that hydropower became widely used.

Mechanical energy is derived by directing, harnessing, or channeling moving water. The amount of available energy in moving water is determined by its flow or fall. Swiftly flowing water in a big river carries a great deal of energy in its flow. So, too, with water descending rapidly from a very high point. In either instance, the water flows through a pipe, or penstock, then pushes against and turns blades in a turbine to spin a generator to produce electricity. In a run-of-the-river system, the force of the current applies the needed pressure, while in a storage system, water is accumulated in reservoirs created by dams, then released when the demand for electricity is high.

Meanwhile, the reservoirs or lakes are used for boating and fishing, and often the rivers beyond the dams provide opportunities for whitewater rafting and kayaking. Hoover

Geothermal Energy - Energy from the Earth's Core

Volcanic energy cannot be harnessed (controlled and collected), but in a few places heat from the earth, called geothermal energy, can be collected. Usually, engineers try to collect this heat in places where the Earth's crust is thin by drilling into the crust and allowing the heat to escape, either as steam, or as very hot water. Pipes carry the hot water to a plant, where some of the steam is allowed to "flash," or separate from the water. That steam then turns a turbine - generator to make electricity.

Geothermal energy was first used to produce electricity in Italy in 1903. At the end of 1998, there were 208 generating units producing electricity from geothermal energy in the USA. Most of these are located in California and Nevada; Utah has two geothermal plants and Hawaii, formed by volcanic eruptions, has one. Generation from geothermal sources is therefore "site specific," meaning it's only possible in a few places under unique geologic conditions. One such site in California, called The Geysers, can produce almost as much electricity as all the other geothermal sites combined.

Geothermal energy can be used as an efficient heat source in small end-use applications such as greenhouses, but the consumers have to be located close to the source of heat. The capital of Iceland, Reykjavik, is heated mostly by geothermal energy.

Geothermal energy has a major environmental benefit because it offsets air pollution that would have been produced if fossil fuels were the energy source. Geothermal energy has a very minor impact on the soil - the few acres used look like a small light-industry building complex. Since the slightly cooler water is reinjected into the ground, there is only a minor impact, except if there is a natural geyser field close by.

Solar Energy - Energy From the Sun

The sun has produced energy for billions of years. Solar energy is the solar radiation that reaches the earth.

Solar power is derived from the energy of the sun. Solar energy can be converted directly or indirectly into other forms of energy, such as heat and electricity. The major drawbacks (problems, or issues to overcome) of solar energy are: (1) the intermittent and variable manner in which it arrives at the earth's surface and, (2) the large area required to collect it at a useful rate.

Solar energy is used for heating water for domestic use, space heating of buildings, drying agricultural products, and generating electrical energy.

In the 1830s, the British astronomer John Herschel used a solar collector box to cook food during an expedition to Africa. Now, people are trying to use the sun's energy for lots of things.

Electric utilities are are trying photovoltaics, a process by which solar energy is converted directly to electricity. Electricity can be produced directly from solar energy using photovoltaic devices or indirectly from steam generators using solar thermal collectors to heat a working fluid.

Wind Energy - Energy from Moving Air

Wind is caused by the uneven heating of the Earth's surface.

Humans have used the wind as an energy source for thousands of years. For example, sails capture the wind to propel ships, the ancient Egyptians used a large paddle wheel to grind grain, and the Dutch used windmills in the 14th century to pump water out of low-lying land.

Today, people around the world are interested in using the wind to generate electricity. The blades of the turbine "catch" the wind, changing its direction from horizontal to vertical, so that the blades spin like a pinwheel. A turbine is then engaged and electricity is generated. The longest windmill blades in use today are 50 feet long. Wind towers, some as tall as ten stories, lift the blades above the ground where stronger wind currents are found.

For a large wind turbine, one that may make electricity for your house, the wind has to blow pretty hard - about 18 miles per hour. But electricity from wind can be generated with wind speeds as low as eight miles per hour. Wind turbines produce no pollution, but they can be pretty noisy.

BIOMASS - Energy from Wood, Garbage, and Agricultural Waste

Biomass is organic material which has stored sunlight in the form of chemical energy. Biomass fuels include wood, wood waste, straw, manure, sugar cane, and many other byproducts from a variety of agricultural processes.

When burned, the chemical energy is released as heat. If you have a fireplace, the wood you burn in it is a biomass fuel. What we now call biomass was the chief source of heating homes and other buildings for thousands of years. In fact, biomass continues to be a major source of energy in much of the developing world.

Sugar cane, a good example of a biomass crop, is grown in many Southern states and in the Caribbean. The chief commercial product, sugar, is extracted from the cane by removing the juice; the remainder of the plant, called "bagasse", still contains the chemical energy of the sun. As with any biomass, bagasse produces heat when burned.