Unit+9

=Alternative Energy=

**What Is Energy?**
Energy makes change possible. We use it to do things for us. It moves cars along the road and boats over the water. It bakes a cake in the oven and keeps ice frozen in the freezer. It plays our favorite songs on the radio and lights our homes. Energy is needed for our bodies to grow and it allows our minds to think. Scientists define energy as the ability to do work. Modern civilization is possible because we have learned how to change energy from one form to another and use it to do work for us and to live more comfortably.

Forms of Energy
Energy is found in different forms including light, heat, chemical, and motion. There are many forms of energy, but they can all be put into two categories: potential and kinetic. Potential energy is stored energy and the energy of position — gravitational energy. There are several forms of potential energy. ||~ ===Kinetic Energy=== Kinetic energy is motion — of waves, molecules, objects, substances, and objects. ||
 * ~ ===Potential Energy===
 * **Chemical Energy** is energy stored in the bonds of atoms and molecules. Biomass, petroleum, natural gas, and coal are examples of stored chemical energy. Chemical energy is converted to thermal energy when we burn wood in a fireplace or burn gasoline in a car's engine.
 * Mechanical Energy** is energy stored in objects by tension. Compressed springs and stretched rubber bands are examples of stored mechanical energy.
 * Nuclear Energy** is energy stored in the nucleus of an atom — the energy that holds the nucleus together. Very large amounts of energy can be released when the nuclei are combined or split apart. Nuclear power plants split the nuclei of uranium atoms in a process called **fission**. The sun combines the nuclei of hydrogen atoms in a process called **fusion**.
 * Gravitational Energy** is energy stored in an object's height. The higher and heavier the object, the more gravitational energy is stored. When you ride a bicycle down a steep hill and pick up speed, the gravitational energy is being converted to motion energy. Hydropower is another example of gravitational energy, where the dam "piles" up water from a river into a reservoir.
 * Electrical Energy** is what is stored in a battery, and can be used to power a cell phone or start a car. Electrical energy is delivered by tiny charged particles called electrons, typically moving through a wire. Lightning is an example of electrical energy in nature, so powerful that it is not confined to a wire. || **Radiant Energy** is electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays and radio waves. Light is one type of radiant energy. Sunshine is radiant energy, which provides the fuel and warmth that make life on Earth possible.
 * Thermal Energy**, or heat, is the vibration and movement of the atoms and molecules within substances. As an object is heated up, its atoms and molecules move and collide faster. Geothermal energy is the thermal energy in the Earth.
 * Motion Energy** is energy stored in the movement of objects. The faster they move, the more energy is stored. It takes energy to get an object moving and energy is released when an object slows down. Wind is an example of motion energy. A dramatic example of motion is a car crash, when the car comes to a total stop and releases all its motion energy at once in an uncontrolled instant.
 * Sound** is the movement of energy through substances in longitudinal (compression/rarefaction) waves. Sound is produced when a force causes an object or substance to vibrate — the energy is transferred through the substance in a wave. Typically, the energy in sound is far less than other forms of energy. ||

=Ecological Footprints=

=Energy Conservation= All of us use energy every day — for transportation, cooking, heating and cooling rooms, manufacturing, lighting, and entertainment. The choices we make about how we use energy — turning machines off when we’re not using them or choosing to buy energy efficient appliances — impact our environment and our lives.
 * Energy conservation** is any behavior that results in the use of less energy. Turning the lights off when you leave the room and recycling aluminum cans are both ways of conserving energy.
 * Energy efficiency** is the use of technology that requires less energy to perform the same function. A compact fluorescent light bulb that uses less energy than an incandescent bulb to produce the same amount of light is an example of energy efficiency. However, the decision to replace an incandescent light bulb with a compact fluorescent is an act of energy conservation.

=Renewable vs Nonrenewable Energy Resources= Energy sources are of two types: nonrenewable and renewable. Energy sources are considered nonrenewable if they cannot be replenished (made again) in a short period of time. On the other hand, renewable energy sources such as solar and wind can be replenished naturally in a short period of time. The four nonrenewable energy sources used most often are:
 * [|Oil and petroleum products] — including [|gasoline], [|diesel fuel], and [|propane]
 * [|Natural gas]
 * [|Coal]
 * [|Uranium (nuclear energy)]

Nonrenewable energy sources come out of the ground as liquids, gases, and solids. Crude oil (petroleum) is the only commercial nonrenewable fuel that is naturally in liquid form. Natural gas and propane are normally gases, and coal is a solid.

Renewable energy sources can be replenished in a short period of time. The five renewable sources used most often are: More than 150 years ago, wood, which is one form of biomass, supplied up to 90% of our energy needs. As the use of coal, petroleum, and natural gas expanded, the United States became less reliant on wood as an energy source. Today, we are looking again at renewable sources to find new ways to use them to help meet our energy needs. In 2008, consumption of renewable sources in the United States totaled 7.3 quadrillion Btu — 1 quadrillion is the number 1 followed by 15 zeros — or about 7% of all energy used nationally.
 * [|Biomass] — including wood and wood waste, municipal solid waste, landfill gas, and biogas, [|ethanol], and [|biodiesel]
 * Water ([|hydropower])
 * [|Geothermal]
 * [|Wind]
 * [|Solar]

=Fossil Fuels=

Oil | Natural Gas | Coal
Fossil fuels like coal, natural gas and oil are non-renewable energy sources formed beneath the surface of the earth from ancient animals and plants. The current concerns about fossil fuel use are focused on issues such as environmental impact, overuse of resources, safety and the possibly dwindling fossil fuel supply.

Crude oil is a fossil fuel that is found deep under the Earth's surface, trapped between the rock layers. It is formed from the remains of plants and animals in the seas, after being subjected to high temperature and pressure conditions. Formation of crude oil require millions of years. As organisms die, they settle at the sea bottom, which are then covered by layers of mud and sediment depositions. The anaerobic microorganisms act slowly on the dead plants and animals in the absence of oxygen, forming carbon-rich organic layers. This organic layer along with sediments is called the source rock (fine-grained shale). Due to the overlying sedimentary layers, the organic layer is subjected to high temperature and pressure. Because of this, distillation of organic material occurs, leading to the formation of crude oil and natural gas. The crude oil formed is accumulated in porous reservoir rocks that can either be limestone or sandstone.
 * Oil**

Natural gas is mostly a mixture of methane, ethane, and propane, with methane making up 73% to 95% of the total. Often found when drilling for oil, natural gas was once considered mainly a bother. When there were no uses or markets to sell natural gas, it was simply flared (burned off) at the wellhead. Major flaring sites were sometimes the brightest areas visible in nighttime satellite images. Today, however, the gas is mostly injected back into the ground for later use and to encourage greater oil production.
 * Natural Gas**


 * 1859 || * Edwin Drake drilled the first commercial well and hit oil and natural gas at 69 feet below the earth's surface. A 2-inch diameter pipeline was built, running 5½ miles from the well to the village of Titusville, Pennsylvania. This milestone may be considered the beginning of the natural gas industry in America. ||
 * 1885 || * Robert Bunsen invented what is now known as the //Bunsen burner.// The Bunsen burner produced a flame that could be safely used for cooking and heating by mixing the right proportion of natural gas and air. The invention of thermostatic devices allowed the flame's temperature to be adjusted and monitored. ||
 * 1890s || * Electricity began to replace natural gas for lighting purposes. ||
 * 1890s || * Electricity began to replace natural gas for lighting purposes. ||
 * 1890s || * Electricity began to replace natural gas for lighting purposes. ||


 * Coal**
 * 1750s || * Coal was reported in Pennsylvania, Ohio, Kentucky, and what is now the state of West Virginia. ||
 * 1758 || * The first commercial coal shipment in the United States was recorded. ||
 * 1762 || * Pennsylvania’s anthracite deposits were found.
 * Coal was used to manufacture shot, shell, and other military materials. ||
 * 1769 || * James Watt patented the modern-day steam engine. Coal was used to produce steam for early steam engines. ||
 * 1800s || * Coal became the principal fuel used by steam-powered trains (locomotives). As the railroads branched into the coal fields, they became a vital link between mines and markets.
 * More and more households and steamboats used coal for fuel.
 * Coal was used to produce oil and gas for lighting. ||
 * 1814 || * Coal was burned to heat salt brines, a source of salt in southwestern Pennsylvania. ||
 * 1816 || * Baltimore, Maryland, became the first city to light streets with gas made from coal. ||
 * 1830s || * Coal was used to make glass in Fayette County, Pennsylvania.
 * Tom Thumb, the first commercially practical American-built steam powered train (locomotive), was manufactured. The Tom Thumb burned coal, and soon, every American locomotive that burned wood was converted to use coal. ||
 * 1848 || * The first coal miners’ union was formed in Schuylkill County, Pennsylvania ||
 * 1814 || * Coal was burned to heat salt brines, a source of salt in southwestern Pennsylvania. ||
 * 1816 || * Baltimore, Maryland, became the first city to light streets with gas made from coal. ||
 * 1830s || * Coal was used to make glass in Fayette County, Pennsylvania.
 * Tom Thumb, the first commercially practical American-built steam powered train (locomotive), was manufactured. The Tom Thumb burned coal, and soon, every American locomotive that burned wood was converted to use coal. ||
 * 1848 || * The first coal miners’ union was formed in Schuylkill County, Pennsylvania ||
 * Tom Thumb, the first commercially practical American-built steam powered train (locomotive), was manufactured. The Tom Thumb burned coal, and soon, every American locomotive that burned wood was converted to use coal. ||
 * 1848 || * The first coal miners’ union was formed in Schuylkill County, Pennsylvania ||
 * 1848 || * The first coal miners’ union was formed in Schuylkill County, Pennsylvania ||

Pro: Low Cost

 * 1) At this time, fossil [[image:http://images.intellitxt.com/ast/adTypes/2_bing.gif width="10" height="10" link="@http://www.ehow.com/facts_5009623_pros-cons-fossil-fuel-energy.html#"]] are relatively cheap and still considered plentiful because there are as yet undiscovered reserves in the earth.

Con: Rising Cost

 * 1) It is widely believed that the cost associated with extracting fossil fuels will continue to rise, especially when the reserves begin to dwindle.

Pro: Controlling Pollution

 * 1) Methods are currently in place to control pollution [[image:http://images.intellitxt.com/ast/adTypes/2_bing.gif width="10" height="10" link="@http://www.ehow.com/facts_5009623_pros-cons-fossil-fuel-energy.html#"]] from fossil fuel extraction and use.

Con: Pollution Control Is Costly

 * 1) The pollution control methods are very expensive to maintain, which has an impact on the price of fuel.

Pro: Safety Advancements

 * 1) Recent technological advancements in fossil fuel extraction have made the process safer than in past years.

Con: Danger Increases

 * 1) Despite the safety measures, extraction is expected to become even more dangerous as mining gets deeper and farther out in the ocean.

=Wind Energy=

Wind is simply air in motion. It is caused by the uneven heating of the Earth's surface by the sun. Because the Earth's surface is made of very different types of land and water, it absorbs the sun's heat at different rates. During the day, the air above the land heats up more quickly than the air over water. The warm air over the land expands and rises, and the heavier, cooler air rushes in to take its place, creating wind. At night, the winds are reversed because the air cools more rapidly over land than over water. In the same way, the atmospheric winds that circle the earth are created because the land near the Earth's equator is heated more by the sun than the land near the North and South Poles. This wind flow, or motion energy, when "harvested" by modern **wind turbines**, can be used to generate **electricity**. The terms "**wind energy**" or "**wind power**" describe the process by which the wind is used to generate **mechanical power or electricity**. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity to power homes, businesses, schools, and the like.

Here are some of the ways in which wind energy proves beneficial to us. Let us now look at the flip side of the coin. Wind energy does have some shortcomings. Find out what are those. =**Energy**= Solar energy is radiant energy that is produced by the sun. Every day the sun radiates, or sends out, an enormous amount of energy. The sun radiates more energy in one second than people have used since the beginning of time! Where does the energy come from that constantly radiates from the sun? It comes from within the sun itself. Like other stars, the sun is a big ball of gases––mostly hydrogen and helium atoms.The hydrogen atoms in the sun’s core combine to form helium and generate energy in a process called **nuclear fusion**. During nuclear fusion, the sun’s extremely high pressure and temperature cause hydrogen atoms to come apart and their nuclei (the central cores of the atoms) to fuse or combine. Four hydrogen nuclei fuse to become one helium atom. But the helium atom contains less mass than the four hydrogen atoms that fused. Some matter is lost during nuclear fusion. The lost matter is emitted into space as radiant energy.
 * Pros of Wind Energy**
 * The biggest benefit one can reap out of wind energy is that it generates electricity, but does not release any harmful pollutants or gases as by products. This therefore makes it a safer and cleaner source of energy.
 * Wind energy is also one of the cheapest forms of energy available today and therefore it can be used by everyone, including poor farmers from rural areas.
 * Farmers can not only use the electricity for themselves, but can also earn income out of it, by providing electricity to several homes.
 * Wind energy does not involve the use of any fossil fuels or non-renewable sources of energy like natural gas, coal or oil. This proves that it is an efficient renewable energy.
 * Wind is a never ending resource, therefore power cuts and power failures are almost non-existent in areas that rely upon wind power to generate electricity.
 * With the use of larger electric grids, higher amount of electricity can be generated, which thus makes electricity accessible to a larger number of households in the vicinity.
 * Cons of Wind Energy**
 * Wind turbines can get damaged or completely destroyed when hit by a heavy storm or a severe lightning.
 * Wind energy helps to solve the electricity problems up to a large extent, but it does not eliminate it completely. It therefore signifies that, we still need to come up with other better options.
 * Wind does not necessarily flow in the same speed all the time. Therefore, the production of electricity would not always remain consistent, there might be ups and downs in its production, depending upon the speed of the wind. This inconsistency in electricity production affects its supply in the nearby high demand areas like cities and towns
 * There have been instances in the past, when the rotating blades of the turbines have proved fatal for birds that happened to hit it.
 * Wind turbines, on an average make a sound of about 50-60 decibel. Slower the wind's speed, larger is the sound produced.
 * In recent times, some people have claimed that wind turbines lower the aesthetic beauty of the land! However, I think that, it is a matter of individual perception and not everyone looks at things in the same way.

Heating with solar energy is not as easy as you might think. Capturing sunlight and putting it to work is difficult because the solar energy that reaches the earth is spread out over such a large area.The sun does not deliver that much energy to any one place at any one time. How much solar energy a place receives depends on several conditions. These include the time of day, the season of the year, the latitude of the area, and the clearness or cloudiness of the sky.A solar collector is one way to collect heat from the sun. A closed car on a sunny day is like a solar collector. As sunlight passes through the car’s glass windows, it is absorbed by the seat covers, walls, and floor of the car. The light that is absorbed changes into heat. The car’s glass windows let light in, but don’t let all the heat out. This is also why greenhouses work so well and stay warm year-round. A greenhouse or solar collector: • allows sunlight in through the glass (or plastic); • absorbs the sunlight and changes it into heat; and • traps most of the heat inside.

The challenge confronting any solar heating system—whether passive, active, or hybrid—is heat storage. Solar heating systems must have some way to store the heat that is collected on sunny days to keep people warm at night or on cloudy days. In passive solar homes, heat is stored by using dense interior materials that retain heat well—masonry, adobe, concrete, stone, or water. These materials absorb surplus heat and radiate it back into the room after dark. Some passive homes have walls up to one foot thick. In active solar homes, heat can be stored in one of two ways—a large tank filled with liquid can be used to store the heat, or rock bins beneath a house can store the heat by heating the air in the bins. Houses with active or passive solar heating systems may also have furnaces, wood-burning stoves, or other heat producing devices to provide heat during extremely cold temperatures or long periods of cold or cloudy weather. These are called backup systems.


 * Photovoltaic** comes from the words photo meaning light and volt, a measurement of electricity. Sometimes photovoltaic cells are called PV cells or solar cells for short. You are probably already familiar with solar cells. Solar-powered calculators, toys, and telephone call boxes all use solar cells to convert light into electricity.Current PV cell technology is not very efficient. Today’s PV cells convert only about 10 to 20 percent of the radiant energy into electrical energy. Fossil fuel plants, on the other hand, convert from 30 to 40 percent of their fuel’s chemical energy into electrical energy.

Using solar energy produces no air or water pollution, and it is a free and widely available energy source. Manufacturing the photovoltaic cells to harness that energy, however, consumes silicon and produces some waste products. In addition, large solar thermal farms can harm desert ecosystems if not properly managed.

=Nuclear Energy= Nuclear energy is energy in the nucleus (core) of an atom. Nuclear energy originates from the splitting of uranium atoms in a process called **fission**. At the power plant, the fission process is used to generate heat for producing steam, which is used by a turbine to generate electricity. he fuel most widely used by nuclear plants for nuclear fission is uranium. Uranium is nonrenewable, though it is a common metal found in rocks all over the world. Nuclear plants use a certain kind of uranium, referred to as U-235. This kind of uranium is used as fuel because its atoms are easily split apart. Though uranium is quite common, about 100 times more common than silver, U-235 is relatively rare. During nuclear fission, a small particle called a neutron hits the uranium atom and splits it, releasing a great amount of energy as heat and radiation. More neutrons are also released. These neutrons go on to bombard other uranium atoms, and the process repeats itself over and over again. This is called a **chain reaction**.

Nuclear power accounted for about 20% of the total net electricity generated in the United States in 2008, about as much as the electricity used in California, Texas, and New York, the three States with the most people.

Just as there are different approaches to designing and building airplanes and automobiles, engineers have developed different types of nuclear power plants. Two types are used in the United States: boiling-water reactors and pressurized-water reactors.

**Boiling-Water Reactors**
In a boiling-water reactor, the water heated by the reactor core turns directly into steam in the reactor vessel and is then used to power the turbine-generator.

**Pressurized-Water Reactors**
In a pressurized-water reactor, the water heated by the reactor core is kept under pressure so that it does not turn to steam at all — it remains liquid. This hot radioactive water flows through a piece of equipment called a steam generator. A steam generator is a giant cylinder with thousands of tubes in it that the hot radioactive water can flow through and heat up. Outside these hot tubes in the steam generator is nonradioactive water (or clean water), which eventually boils and turns to steam. Unlike fossil fuel-fired power plants, nuclear reactors do not produce air pollution or carbon dioxide while operating. However, the processes for mining and refining uranium ore and making reactor fuel require large amounts of energy. Nuclear power plants have large amounts of metal and concrete, which also require large amounts of energy to manufacture. If fossil fuels are used to make the electricity and manufacture the power plant materials, then the emissions from burning those fuels could be associated with the electricity that nuclear power plants generate.

The main environmental concerns for nuclear power are radioactive wastes such as uranium mill tailings, spent (used) reactor fuel, and other radioactive wastes. These materials can remain radioactive and dangerous to human health for thousands of years. They are subject to special regulations that govern their handling, transportation, storage, and disposal to protect human health and the environment. The U.S. Nuclear Regulatory Commission regulates the operation of nuclear power plants. Spent reactor fuel (used fuel) assemblies are highly radioactive and must initially be stored in specially designed pools resembling large swimming pools, where water cools the fuel and acts as a radiation shield, or in specially designed dry storage containers. An increasing number of reactor operators now store their older spent fuel in dry storage facilities using special outdoor concrete or steel containers with air cooling. There is currently no permanent disposal facility in the United States for high-level nuclear waste. High-level waste is being stored at nuclear plants.

=Biomass= We have used biomass energy, or "bioenergy"—the energy from plants and plant-derived materials�since people began burning wood to cook food and keep warm. Wood is still the largest biomass energy resource today, but other sources of biomass can also be used. These include food crops, grassy and woody plants, residues from agriculture or forestry, oil-rich algae, and the organic component of municipal and industrial wastes. Even the fumes from landfills (which are methane, a natural gas) can be used as a biomass energy source.

=Geothermal Energy= The word geothermal comes from the Greek words //geo// (earth) and //therme// (heat). So, geothermal energy is heat from within the Earth. We can recover this heat as steam or hot water and use it to heat buildings or generate electricity. Geothermal energy is a renewable energy source because the heat is continuously produced inside the Earth. Geothermal energy is generated in the Earth's core. Temperatures hotter than the sun's surface are continuously produced inside the Earth by the slow decay of radioactive particles, a process that happens in all rocks. The Earth has a number of different layers: The Earth's crust is broken into pieces called plates. Magma comes close to the Earth's surface near the edges of these plates. This is where volcanoes occur. The lava that erupts from volcanoes is partly magma. Deep underground, the rocks and water absorb the heat from this magma. The temperature of the rocks and water gets hotter and hotter as you go deeper underground. People around the world use geothermal energy to heat their homes and to produce electricity by digging deep wells and pumping the heated underground water or steam to the surface. We can also make use of the stable temperatures near the surface of the Earth to heat and cool buildings. Naturally occurring large areas of hydrothermal resources are called **geothermal reservoirs**. Most geothermal reservoirs are deep underground with no visible clues showing above ground. But geothermal energy sometimes finds its way to the surface in the form of:
 * The core itself has two layers: a solid iron core and an outer core made of very hot melted rock, called magma.
 * The mantle surrounds the core and is about 1,800 miles thick. It is made up of magma and rock.
 * The crust is the outermost layer of the Earth, the land that forms the continents and ocean floors. It can be 3 to 5 miles thick under the oceans and 15 to 35 miles thick on the continents.
 * **Volcanoes** and **fumaroles** (holes where volcanic gases are released)
 * **Hot springs**
 * **Geysers**

Some applications of geothermal energy use the Earth's temperatures near the surface, while others require drilling miles into the Earth. The three main uses of geothermal energy are:
 * **Direct use and district heating systems** use hot water from springs or reservoirs near the surface.
 * **Electricity generation power plants** require water or steam at very high temperature (300° to 700°F). Geothermal power plants are generally built where geothermal reservoirs are located within a mile or two of the surface.
 * **Geothermal heat pumps** use stable ground or water temperatures near the Earth's surface to control building temperatures above ground.

Direct Use of Geothermal Energy
There have been **direct uses** of hot water as an energy source since ancient times. Ancient Romans, Chinese, and Native American cultures used hot mineral springs for bathing, cooking, and heating. Today, many hot springs are still used for bathing, and many people believe the hot, mineral-rich waters have natural healing powers. After bathing, the most common direct use of geothermal energy is for heating buildings through **district heating systems**. Hot water near the Earth's surface can be piped directly into buildings and industries for heat. A district heating system provides heat for 95% of the buildings in Reykjavik, Iceland. Industrial applications of geothermal energy include food dehydration, gold mining, and milk pasteurizing. Dehydration, or the drying of vegetable and fruit products, is the most common industrial use of geothermal energy.

The United States Is the Leader in Geothermal Power Generation
The United States leads the world in electricity generation with geothermal power. In 2008, U.S. geothermal power plants produced 14.86 billion kilowatt-hours, or 0.4% of total U.S. electricity generation. Seven States have geothermal power plants:
 * California has 34 geothermal power plants, which produce almost 90% of U.S. geothermal electricity.
 * Nevada has 16 geothermal power plants.
 * Hawaii, Idaho, Montana, and Utah each have one geothermal plant.

=Hydropower Energy=