Solar energy is any type of energy generated by the sun, Solar energy is created by nuclear fusion that takes place in the sun, Fusion occurs when protons of hydrogen atoms violently collide in the sun ‘s core and fuse to create a helium atom. This process, known as a PP (proton-proton) chain reaction, emits an enormous amount of energy.
- In its core, the sun fuses about 620 million metric tons of hydrogen every second.
- The PP chain reaction occurs in other stars that are about the size of our sun, and provides them with continuous energy and heat.
- The temperature for these stars is around 4 million degrees on the Kelvin scale (about 4 million degrees Celsius, 7 million degrees Fahrenheit).
In stars that are about 1.3 times bigger than the sun, the CNO cycle drives the creation of energy. The CNO cycle also converts hydrogen to helium, but relies on carbon, nitrogen, and oxygen (C, N, and O) to do so. Currently, less than 2% of the sun ‘s energy is created by the CNO cycle.
- Nuclear fusion by the PP chain reaction or CNO cycle releases tremendous amounts of energy in the form of waves and particles.
- Solar energy is constantly flowing away from the sun and throughout the solar system,
- Solar energy warms the Earth, causes wind and weather, and sustains plant and animal life.
The energy, heat, and light from the sun flow away in the form of electromagnetic radiation (EMR). The electromagnetic spectrum exists as waves of different frequencies and wavelengths. The frequency of a wave represents how many times the wave repeats itself in a certain unit of time.
Waves with very short wavelengths repeat themselves several times in a given unit of time, so they are high- frequency, In contrast, low- frequency waves have much longer wavelengths. The vast majority of electromagnetic waves are invisible to us. The most high- frequency waves emitted by the sun are gamma rays, X-rays, and ultraviolet radiation (UV rays).
The most harmful UV rays are almost completely absorbed by Earth’s atmosphere, Less potent UV rays travel through the atmosphere, and can cause sunburn, The sun also emits infrared radiation, whose waves are much lower- frequency, Most heat from the sun arrives as infrared energy.
Sandwiched between infrared and UV is the visible spectrum, which contains all the colors we see on Earth. The color red has the longest wavelengths (closest to infrared), and violet (closest to UV) the shortest. Natural Solar Energy Greenhouse Effect The infrared, visible, and UV waves that reach the Earth take part in a process of warming the planet and making life possible—the so-called ” greenhouse effect,” About 30% of the solar energy that reaches Earth is reflected back into space.
The rest is absorbed into Earth’s atmosphere, The radiation warms the Earth’s surface, and the surface radiates some of the energy back out in the form of infrared waves. As they rise through the atmosphere, they are intercepted by greenhouse gases, such as water vapor and carbon dioxide.
Greenhouse gases trap the heat that reflects back up into the atmosphere. In this way, they act like the glass walls of a greenhouse. This greenhouse effect keeps the Earth warm enough to sustain life. Photosynthesis Almost all life on Earth relies on solar energy for food, either directly or indirectly.
Producers rely directly on solar energy, They absorb sunlight and convert it into nutrients through a process called photosynthesis, Producers, also called autotrophs, include plants, algae, bacteria, and fungi. Autotrophs are the foundation of the food web,
Consumers rely on producers for nutrients, Herbivores, carnivores, omnivores, and detritivores rely on solar energy indirectly. Herbivores eat plants and other producers. Carnivores and omnivores eat both producers and herbivores. Detritivores decompose plant and animal matter by consuming it. Fossil Fuels Photosynthesis is also responsible for all of the fossil fuels on Earth.
Scientists estimate that about 3 billion years ago, the first autotrophs evolved in aquatic settings. Sunlight allowed plant life to thrive and evolve. After the autotrophs died, they decomposed and shifted deeper into the Earth, sometimes thousands of meters.
This process continued for millions of years. Under intense pressure and high temperatures, these remains became what we know as fossil fuels, Microorganisms became petroleum, natural gas, and coal. People have developed processes for extracting these fossil fuels and using them for energy. However, fossil fuels are a nonrenewable resource,
They take millions of years to form. Harnessing Solar Energy Solar energy is a renewable resource, and many technologies can harvest it directly for use in homes, businesses, schools, and hospitals. Some solar energy technologies include photovoltaic cells and panels, concentrated solar energy, and solar architecture,
There are different ways of capturing solar radiation and converting it into usable energy. The methods use either active solar energy or passive solar energy, Active solar technologies use electrical or mechanical devices to actively convert solar energy into another form of energy, most often heat or electricity.
Passive solar technologies do not use any external devices. Instead, they take advantage of the local climate to heat structures during the winter, and reflect heat during the summer. Photovoltaics Photovoltaics is a form of active solar technology that was discovered in 1839 by 19-year-old French physicist Alexandre-Edmond Becquerel.
Becquerel discovered that when he placed silver-chloride in an acidic solution and exposed it to sunlight, the platinum electrodes attached to it generated an electric current, This process of generating electricity directly from solar radiation is called the photovoltaic effect, or photovoltaics,
Today, photovoltaics is probably the most familiar way to harness solar energy, Photovoltaic arrays usually involve solar panels, a collection of dozens or even hundreds of solar cells. Each solar cell contains a semiconductor, usually made of silicon.
- When the semiconductor absorbs sunlight, it knocks electrons loose.
- An electrical field directs these loose electrons into an electric current, flowing in one direction.
- Metal contacts at the top and bottom of a solar cell direct that current to an external object.
- The external object can be as small as a solar-powered calculator or as large as a power station.
Photovoltaics was first widely used on spacecraft. Many satellites, including the International Space Station, feature wide, reflective “wings” of solar panels, The ISS has two solar array wings (SAWs), each using about 33,000 solar cells. These photovoltaic cells supply all electricity to the ISS, allowing astronauts to operate the station, safely live in space for months at a time, and conduct scientific and engineering experiments.
- Photovoltaic power stations have been built all over the world.
- The largest stations are in the United States, India, and China.
- These power stations emit hundreds of megawatts of electricity, used to supply homes, businesses, schools, and hospitals.
- Photovoltaic technology can also be installed on a smaller scale.
Solar panels and cells can be fixed to the roofs or exterior walls of buildings, supplying electricity for the structure. They can be placed along roads to light highways. Solar cells are small enough to power even smaller devices, such as calculators, parking meters, trash compactors, and water pumps.
Concentrated Solar Energy Another type of active solar technology is concentrated solar energy or concentrated solar power (CSP). CSP technology uses lenses and mirrors to focus (concentrate) sunlight from a large area into a much smaller area. This intense area of radiation heats a fluid, which in turn generates electricity or fuels another process.
Solar furnaces are an example of concentrated solar power. There are many different types of solar furnaces, including solar power towers, parabolic troughs, and Fresnel reflectors. They use the same general method to capture and convert energy. Solar power towers use heliostats, flat mirrors that turn to follow the sun ‘s arc through the sky.
The mirrors are arranged around a central “collector tower,” and reflect sunlight into a concentrated ray of light that shines on a focal point on the tower. In previous designs of solar power towers, the concentrated sunlight heated a container of water, which produced steam that powered a turbine,
More recently, some solar power towers use liquid sodium, which has a higher heat capacity and retains heat for a longer period of time. This means that the fluid not only reaches temperatures of 773 to 1,273 K (500 to 1,000° C or 932 to 1,832° F), but it can continue to boil water and generate power even when the sun is not shining.
Parabolic troughs and Fresnel reflectors also use CSP, but their mirrors are shaped differently. Parabolic mirrors are curved, with a shape similar to a saddle. Fresnel reflectors use flat, thin strips of mirror to capture sunlight and direct it onto a tube of liquid. Fresnel reflectors have more surface area than parabolic troughs and can concentrate the sun ‘s energy to about 30 times its normal intensity.
Concentrated solar power plants were first developed in the 1980s. The largest facility in the world is a series of plants in California’s Mojave Desert. This Solar Energy Generating System (SEGS) generates more than 650 gigawatt-hours of electricity every year.
- Other large and effective plants have been developed in Spain and India.
- Concentrated solar power can also be used on a smaller scale.
- It can generate heat for solar cookers, for instance.
- People in villages all over the world use solar cookers to boil water for sanitation and to cook food.
- Solar cookers provide many advantages over wood-burning stoves: They are not a fire hazard, do not produce smoke, do not require fuel, and reduce habitat loss in forests where trees would be harvested for fuel.
Solar cookers also allow villagers to pursue time for education, business, health, or family during time that was previously used for gathering firewood. Solar cookers are used in areas as diverse as Chad, Israel, India, and Peru. Solar Architecture Throughout the course of a day, solar energy is part of the process of thermal convection, or the movement of heat from a warmer space to a cooler one.
When the sun rises, it begins to warm objects and material on Earth. Throughout the day, these materials absorb heat from solar radiation. At night, when the sun sets and the atmosphere has cooled, the materials release their heat back into the atmosphere, Passive solar energy techniques take advantage of this natural heating and cooling process.
Homes and other buildings use passive solar energy to distribute heat efficiently and inexpensively. Calculating a building’s ” thermal mass ” is an example of this. A building’s thermal mass is the bulk of material heated throughout the day. Examples of a building’s thermal mass are wood, metal, concrete, clay, stone, or mud.
At night, the thermal mass releases its heat back into the room. Effective ventilation systems—hallways, windows, and air ducts—distribute the warmed air and maintain a moderate, consistent indoor temperature. Passive solar technology is often involved in the design of a building. For example, in the planning stage of construction, the engineer or architect may align the building with the sun ‘s daily path to receive desirable amounts of sunlight,
This method takes into account the latitude, altitude, and typical cloud cover of a specific area. In addition, buildings can be constructed or retrofitted to have thermal insulation, thermal mass, or extra shading. Other examples of passive solar architecture are cool roofs, radiant barriers, and green roofs,
Cool roofs are painted white, and reflect the sun ‘s radiation instead of absorbing it. The white surface reduces the amount of heat that reaches the interior of the building, which in turn reduces the amount of energy that is needed to cool the building. Radiant barriers work similarly to cool roofs.
They provide insulation with highly reflective materials, such as aluminum foil. The foil reflects, instead of absorbs, heat, and can reduce cooling costs up to 10%. In addition to roofs and attics, radiant barriers may also be installed beneath floors.
Green roofs are roofs that are completely covered with vegetation, They require soil and irrigation to support the plants, and a waterproof layer beneath. Green roofs not only reduce the amount of heat that is absorbed or lost, but also provide vegetation, Through photosynthesis, the plants on green roofs absorb carbon dioxide and emit oxygen.
They filter pollutants out of rainwater and air, and offset some of the effects of energy use in that space. Green roofs have been a tradition in Scandinavia for centuries, and have recently become popular in Australia, Western Europe, Canada, and the United States.
- For example, the Ford Motor Company covered 42,000 square meters (450,000 square feet) of its assembly plant roofs in Dearborn, Michigan, with vegetation,
- In addition to reducing greenhouse gas emissions, the roofs reduce stormwater runoff by absorbing several centimeters of rainfall.
- Green roofs and cool roofs can also counteract the ” urban heat island ” effect.
In busy cities, the temperature can be consistently higher than the surrounding areas. Many factors contribute to this: Cities are constructed of materials such as asphalt and concrete that absorb heat; tall buildings block wind and its cooling effects; and high amounts of waste heat is generated by industry, traffic, and high populations.
Using the available space on the roof to plant trees, or reflecting heat with white roofs, can partially alleviate local temperature increases in urban areas. Solar Energy and People Since sunlight only shines for about half of the day in most parts of the world, solar energy technologies have to include methods of storing the energy during dark hours.
Thermal mass systems use paraffin wax or various forms of salt to store the energy in the form of heat. Photovoltaic systems can send excess electricity to the local power grid, or store the energy in rechargeable batteries. There are many pros and cons to using solar energy,
Advantages A major advantage to using solar energy is that it is a renewable resource, We will have a steady, limitless supply of sunlight for another 5 billion years. In one hour, the Earth’s atmosphere receives enough sunlight to power the electricity needs of every human being on Earth for a year.
Solar energy is clean. After the solar technology equipment is constructed and put in place, solar energy does not need fuel to work. It also does not emit greenhouse gases or toxic materials. Using solar energy can drastically reduce the impact we have on the environment.
There are locations where solar energy is practical, Homes and buildings in areas with high amounts of sunlight and low cloud cover have the opportunity to harness the sun ‘s abundant energy. Solar cookers provide an excellent alternative to cooking with wood-fired stoves—on which 2 billion people still rely.
Solar cookers provide a cleaner and safer way to sanitize water and cook food. Solar energy complements other renewable sources of energy, such as wind or hydroelectric energy, Homes or businesses that install successful solar panels can actually produce excess electricity.
- These homeowners or businessowners can sell energy back to the electric provider, reducing or even eliminating power bills.
- Disadvantages The main deterrent to using solar energy is the required equipment.
- Solar technology equipment is expensive.
- Purchasing and installing the equipment can cost tens of thousands of dollars for individual homes.
Although the government often offers reduced taxes to people and businesses using solar energy, and the technology can eliminate electricity bills, the initial cost is too steep for many to consider. Solar energy equipment is also heavy. In order to retrofit or install solar panels on the roof of a building, the roof must be strong, large, and oriented toward the sun ‘s path.
- Both active and passive solar technology depend on factors that are out of our control, such as climate and cloud cover,
- Local areas must be studied to determine whether or not solar power would be effective in that area.
- Sunlight must be abundant and consistent for solar energy to be an efficient choice.
In most places on Earth, sunlight ‘s variability makes it difficult to implement as the only source of energy. Fast Fact Agua Caliente The Agua Caliente Solar Project, in Yuma, Arizona, is the world’s largest array of photovoltaic panels. Agua Caliente has more than 5 million photovoltaic modules, and generates more than 600 gigawatt-hours of electricity.
Fast Fact Green Chicago Millennium Park in Chicago, Illinois, has one of the most expansive green roofs in the worldalmost 100,000 square meters (more than a million square feet). Vegetation at ground level covers 24.5 acres of an underground parking garage, and includes gardens, picnic areas, and an outdoor concert facility.
Fast Fact Solar Decathlon The Solar Decathlon is a biannual international event presented by the U.S. Department of Energy. Teams compete to design, build, and operate the most attractive, effective, and energy-efficient solar-powered house. A team from the University of Maryland won the 2011 contest, and the next Solar Decathlon will be held in 2013,
What is the natural source of solar energy?
Solar Energy – Solar energy is energy provided by the Sun in the form of solar radiation. Every day the Sun radiates, or sends out, an enormous amount of energy. This Radiant energy has powered life on earth for millions of years and is one of the most important source of energy for life forms.
Why is solar energy a source?
Limitless solar energy – The sun provides more than enough energy to meet the whole world’s energy needs, and unlike fossil fuels, it won’t run out anytime soon. As a renewable energy source, the only limitation of solar power is our ability to turn it into electricity in an efficient and cost-effective way.
What is the main source of energy?
ENERGY AND TIME GOAL: To be aware of the different forms of energy and the time frame necessary for the development of these energy forms. OBJECTIVE: 1. The student will become familiar with different forms of energy.2. The student will understand the sources of energy.3.
The student will acquire an understanding of the history of various sources of energy. LESSON / INFORMATION: Are energy sources renewable or nonrenewable? You can decide for yourself. If a source of energy is replaced as we use it, so that we can never use it up, it is called renewable. If there is a definite, limited supply of a source of energy, and it cannot be replaced, it is called nonrenewable.
This is an important idea, because it helps us to decide how we should use each of our many sources of energy. Energy is all around us and comes from many sources. One of the most important sources of energy is the sun. The energy of the sun is the original source of most of the energy found on earth. We get solar heat energy from the sun, and sunlight can also be used to produce electricity from solar ( photovoltaic ) cells. The sun heats the earth’s surface and the Earth heats the air above it, causing wind, Water evaporated by the sun forms clouds and rain to give us flowing streams and rivers. Both wind and flowing water ( hydropower ) are sources of energy. So you see, the sun is the source of many kinds of energy found in nature. These kinds of energy are around us all the time. They are produced quickly, and replace themselves constantly as we use them. For this reason we say they are renewable. The sun’s energy can also be stored. When energy is stored in a material, we call that material fuel. Food and wood are biomass fuels. When you have old biomass that has become concentrated, you have what we call “fossil fuel”. THE FORMATION OF FOSSIL FUELS Fossil fuels are found deposited in rock formations.
They were formed there between 350 million and 50 million years ago. The processes by which they were formed are not totally understood. Decayed remains of ancient plants and/or animals were buried by sediments. Through the action of heat and pressure over millions of centuries, they were chemically changed.
Coal, oil, and natural gas are the results. Coal was formed from the remains of ferns, trees, and grasses that grew in great swamps 345 million years ago. These remains formed layers as they sank under the water of the swamps. The plant material partially decayed as these layers formed beds of peat, a soft brown substance that is up to 30% carbon.
Peat is the earliest stage of coal formation. Shallow seas later covered the swamps and slowly deposited layers of sand and mud over the peat. These sediments exerted pressure on the peat over thousands of years. Slowly, chemical changes took place transforming it into lignite or brown coal, which is about 40% carbon.
Millions of years later, increasing pressure and heat changed lignite into bituminous or soft coal (about 66% carbon) and finally into anthracite or hard coal (over 90% carbon). Oil and natural gas are also found in beds of sedimentary rock. The sediments were deposited by shallow seas millions of years ago.
- The remains of plants and animals living in the seas settled to the bottom and were buried under layers of sediment.
- These layers were subjected to heat and pressure over millions of years.
- The sediments were transformed into beds of rock, and the plant and animal remains underwent slow chemical change and formed oil and natural gas.
As you can see, the fossil fuels take millions of years to form. They cannot be replaced quickly. In fact, in terms of our lifetime they cannot be replaced at all. For that reason we call them nonrenewable. OTHER ENERGY FORMS There are still other kinds of energy: ocean thermal energy, geothermal energy, and nuclear energy, for example. A QUICK ENERGY HISTORY Pre 1700’s The story of American life is an energy story. The first Americans, Native Americans, used their own muscle power to do work and to travel. They burned wood for cooking and heating. They used the sun’s energy to dry food and animal skins.
- The 1700’s When settlers came from Europe, they used these same kinds of energy, but they also used some new ones.
- They used wind power to drive the ships that brought them here.
- They used animal power to help with their work and travel.
- They also built mills that used water power to grind grain, saw wood and pump water.
Wood was still their main fuel. The 1800’s America’s population grew. People wanted more food, faster travel, better clothing and shelter. The new steam engine could be used to run machines, ships, and trains, but it needed fuel. Factories and railroads grew, using more and more fuel.
- In some places, wood became scarce so coal began to replace wood.
- For lighting, coal gas and natural gas began to take the place of candles and whale oil.
- People learned to break down oil into products like kerosene for lighting and cooking.
- Then the automobile was invented.
- Soon a lot of oil would be needed to make gasoline for cars.
The 1900’s A greater dependence on electricity became apparent. Electric lights, appliances and machines made life easier for Americans. Coal, oil, natural gas and hydro (water) power were all used for making electricity. Then nuclear energy was discovered, and it was also used to make electricity.
Americans used a lot of oil. We used it to make electricity, to make fuels for transportation and heating, and to make many products like plastic and nylon. The price of oil went up, and so did the prices of electricity and gasoline. The supplies are finite and continue to dwindle at an accelerated rate.
People began to conserve energy. They began to use the kinds of energy that Native Americans and early settlers had used, energy from the sun, the wind, and wood. They also searched for new sources of energy, and new ways to use energy for the future. The 2,000’s Predict the future in energy development in the 2,000’s. Chart reprinted with permission from the New York Energy Education Handbook, New York State Dept. of Education. QUESTIONS: 1. What were the most important kinds of energy in the early days of America? What were they used for? 2. The American Revolution was in the 1770’s.
- What was the most used fuel then? 3.
- The American Civil War was in the 1860’s.
- What was the most used fuel then? 4.
- Why did coal become so important by 1900? 5.
- Why do you think it took so long for coal to replace wood as the most important fuel? 6.
- What was the most used fuel in 1975.
- What use did it have? 7.
Why do you think oil use went down and wood use went up during the 1970’s? 8. What sources of energy does the U.S. depend on most today? ACTIVITY 2: Match the pictures below with the correct titles. _1. Solar Thermal Energy _2. Biomass _3. Hydropower _4. Wind _5.
Geothermal _6. Photovoltaic A B C D E F INFORMATION CHECK Directions: After studying the information provided, fill in the blanks below. The _ is the original source of almost all the energy on earth. Energy appears in many different forms, but if you trace it back far enough, you find that it all started at the same place: the _.
Some sources of energy exist in almost unlimited supply. As soon as we use some energy, it is replaced by more. For this reason, we say that these sources of energy are _. Perhaps the “fastest” energy is _ electricity, which is produced when sunlight strikes solar cells.
These are the round, bluish wafers that are mounted on space satellites to give them electric power from sunlight when they are in space. It only takes the sun a few minutes to give us direct solar _. You can feel it in a car that sits in the sun. Houses and buildings can be designed to collect sunlight the same way.
You can also build solar collectors to trap the sun’s heat. The sun heats the earth and the earth warms the air above it. Heated air rises (just like a hot air balloon). When cooler air rushes in to displace the heated air, we have _. This energy can be used to sail ships or drive machines to pump water or produce electricity.
- The sun heats the surface water of lakes and oceans.
- Some of the water evaporates when it is heated.
- Then it forms clouds, falls as rain, and collects in lakes and rivers.
- As this water flows back to the sea it provides _ which can drive a turbine to generate electricity.
- The plants of the earth are solar collectors.
By the process of photosynthesis, they use sunlight to produce stored chemical energy that is used for food or fuel. Plant energy is called _. Some sources of energy take so long to produce that if we use them up they can’t be replaced. _, _, and _ are like that.
Dead plants and animals must decay for hundreds to millions of years to produce these fossil fuels. That is why we say they are _. RECOMMENDED READING: New York Energy Education Project, Research Foundation of the State University of New York. Albany, NY.1985 TEACHER’S NOTES DEFINITIONS: Are they renewable or nonrenewable? You can decide for yourself.
If a source of energy is replaced as we use it, so that we can never use it up, it is called renewable. If there is a definite, limited supply of a source of energy, and it cannot be replaced, it is called nonrenewable. This is an important idea, because it helps us to decide how we should use each of our many sources of energy.
- Quad – A gigantic energy unit (often used to state how much energy entire countries buy each year).
- It represents a quadrillion Btu’s, the amount of heat energy in 172 million barrels of oil; a unit of energy equal to one quadrillion Btu’s (1,000,000,000,000,000).
- ANSWERS TO QUESTIONS: 1.
- Coal and wood were the most important energy sources in the early days of America.2.
The most used fuel during the 1770’s was wood.3. During the 1860’s wood was still the most used fuel.4. Coal became important just prior to 1900 because of its many uses such as the fuel for steam engines which powered the many railroad engines popular during the period, and fuel for the steam turbines used in the production of electricity.
Coal also began to replace wood as a source of heat for commercial and residential buildings.5. Wood remained the most popular fuel for a long period of time because of its abundance and the fact that it was extremely inexpensive.6. Oil was the most important fuel in 1975. Fuel oil derived from oil became extremely important at this time due to the mobility of the world’s people and the so called “Shrinking of the globe” by faster and faster means of transportation.7.
Oil went down due to energy conservation measures and the high price of fuel oil brought on by the Arab oil embargo.8. The United States is still highly dependent on oil as its main source of energy. This is a serious problem due to its shrinking supply.
- Alternative sources such as atomic energy, natural gas and renewable sources need to be developed in the near future to avoid catastrophic consequences.
- ANSWERS TO ACTIVITY 2 1. = D 2. = B 3. = A 4. = E 5. = F 6.
- = C ANSWERS TO INFORMATION CHECK: The _SUN_ is the original source of almost all the energy on earth.
Energy appears in many different forms, but if you trace it back far enough, you find that it all started at the same place: the _SUN_. Some sources of energy exist in almost unlimited supply. As soon as we use some energy, it is replaced by more. For this reason, we say that these sources of energy are _RENEWABLE_.
- Perhaps the “fastest” energy is _SOLAR_ electricity, which is produced when sunlight strikes solar cells.
- These are the round, bluish wafers that are mounted on space satellites to give them electric power from sunlight when they are in space.
- It only takes the sun a few minutes to give us direct solar _ENERGY_.
You can feel it in a car that sits in the sun. Houses and buildings can be designed to collect sunlight the same way. You can also build solar collectors to trap the sun’s heat. The sun heats the earth and the earth warms the air above it. Heated air rises (just like a hot air balloon).
- When cooler air rushes in to displace the heated air, we have _WIND_.
- This energy can be used to sail ships or drive machines to pump water or produce electricity.
- The sun heats the surface water of lakes and oceans.
- Some of the water evaporates when it is heated.
- Then it forms clouds, falls as rain, and collects in lakes and rivers.
As this water flows back to the sea it provides _HYDROPOWER_ which can drive a turbine to generate electricity. The plants of the earth are solar collectors. By the process of photosynthesis, they use sunlight to produce stored chemical energy that is used for food or fuel.
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: ENERGY AND TIME
What is solar explain?
Solar energy is defined as the transformation of energy that is present in the sun and is one of the renewable energies. Once the sunlight passes through the earth’s atmosphere, most of it is in the form of visible light and infrared radiation.
What are the 3 source of energy?
There are three main categories of energy sources: fossil fuel, alternative, and renewable. Renewable is sometimes, but not always, included under alternative. – Fossil fuels formed over millions of years ago as dead plants and animals were subjected to extreme heat and pressure in the earth’s crust.
Petroleum is an umbrella term that includes products such as crude oil, which is refined into more familiar fuels such as gasoline, jet fuel, kerosene, and diesel. Petroleum and oil are often used interchangeably. It is extracted through drilling or hydraulic fracturing (also known as fracking ). Coal is a rock found close to the earth’s surface and is one of the world’s most abundant fossil fuels. It is extracted through surface mining (using machines to clear away the uppermost layers of rock and soil) and underground mining (using machines and miners to remove coal deep underground). Natural gas, a mixture of gases trapped underneath the earth’s surface, is extracted in similar ways as oil. Advances in drilling and fracking have unlocked vast reserves of natural gas.
Fossil fuels are often called dirty energy sources because using them comes at a high—and often irreversible—cost to the environment. Carbon emissions, or the amount of carbon dioxide these fuels release into the atmosphere, add up over generations and cannot be taken back.
Moreover, there is only a finite amount of these resources on earth. Forms of energy not derived from fossil fuels include both renewable and alternative energy, terms that are sometimes used interchangeably but do not mean the same thing. Alternative energy broadly refers to any energy that is not extracted from a fossil fuel, but not necessarily only from a renewable source.
For example, nuclear power generation most commonly uses uranium, an abundant but not technically renewable fuel. Renewable energy, on the other hand, includes sources such as sun and wind that occur naturally and continuously. There are five main renewable and alternative fuels.
Wind power is created when wind spins a turbine, or a windmill, which can be located on land or offshore. Solar power harnesses the sun’s energy in two ways: by converting the sun’s light directly into electricity when the sun is out (think solar panels), or solar thermal energy, which uses the sun’s heat to create electricity, a method that works even when the sun is down. Hydropower is created when rapidly flowing water turns turbines inside a dam, generating electricity. Nuclear energy is produced at power plants by the process of nuclear fission, The energy created during nuclear reactions is harnessed to produce electricity. Biofuels, also referred to as biomass, are produced using organic materials (wood, agricultural crops and waste, food waste, and animal manure) that contain stored energy from the sun. Humans have used biomass since they discovered how to burn wood to make fire. Liquid biofuels, such as ethanol, also release chemical energy in the form of heat.
Renewable and alternative energy sources are often categorized as clean energy because they produce significantly less carbon emissions compared to fossil fuels. But they are not without environmental footprint. Hydropower generation, for example, releases lower carbon emissions than fossil fuel plants do.
- However, damming water to build reservoirs for hydropower floods valleys, disrupting local ecosystems and livelihoods.
- In another case, biofuels are renewable but are cultivated on huge swaths of land and sometimes generate more carbon emissions than fossil fuels do.
- Other considerations such as safety also matter.
The likelihood of a meltdown at a nuclear facility is exceedingly small, but if one were to occur, the results would be catastrophic. In fact, concerns about the dangers associated with operating nuclear power plants have limited the expansion of nuclear energy.
Is solar energy is renewable?
Solar energy is that produced by the Sun’s light – photovoltaic energy – and its warmth – solar thermal – for the generation of electricity or the production of heat. Inexhaustible and renewable, since it comes from the Sun, solar energy is harnessed using panels and mirrors.
Why is solar energy called renewable?
Renewable energy is energy derived from natural sources that are replenished at a higher rate than they are consumed. Sunlight and wind, for example, are such sources that are constantly being replenished. Renewable energy sources are plentiful and all around us.
Fossil fuels – coal, oil and gas – on the other hand, are non-renewable resources that take hundreds of millions of years to form. Fossil fuels, when burned to produce energy, cause harmful greenhouse gas emissions, such as carbon dioxide. Generating renewable energy creates far lower emissions than burning fossil fuels.
Transitioning from fossil fuels, which currently account for the lion’s share of emissions, to renewable energy is key to addressing the climate crisis. Renewables are now cheaper in most countries, and generate three times more jobs than fossil fuels.