Use of solar energy. Use of solar energy on Earth. Prospects for the use of solar energy on Earth Solar energy is only used

There are two main directions for using solar energy: generating electrical energy and obtaining thermal energy (heat supply). The use of solar power generators is still in its early stages, but the use of solar heat supply for heating residential buildings already occupies a significant place in world practice.

Thus, in the USA in 1977 there were about 1000 solar houses, in the 90s. their number exceeded 15 thousand. 90% of houses in Cyprus and 70% in Israel have solar installations for heating water. In the last 15 years alone, Japan has built hundreds of thousands of solar-heated buildings, dramatically reducing emissions of carbon dioxide and other greenhouse gases.

Solar energy in Russia is completely underdeveloped, although half of its territory is in favorable conditions for the use of solar energy - at least 100 kWh/m 2 is supplied per year, and in such areas as Dagestan, Buryatia, Primorye, Astrakhan region, etc. . – up to 200 kW h/m 2 .

Solar energy is very convenient for powering buildings. As experimental studies have shown, only due to the energy of solar rays falling on the enclosing structures of buildings, it is possible to completely solve the energy problems associated with their heating, hot water supply, etc.

There are three types of solar systems that serve to meet the thermal needs of a building: passive, active and mixed.

In passive solar systems, the building itself serves as a receiver and converter of solar energy, and heat distribution is carried out by convention.

The main element of a more expensive active solar system is a collector - a receiver of solar energy, where sunlight is converted into heat. The solar collector is a thermally insulated box: visible light from the sun passes through a transparent coating (glass or film), hits a blackened panel and heats it. With a special design of the collector, a very high temperature is reached inside it, allowing for successful hot water supply.

Assessing the effectiveness of using solar heat supply in our country, N. Pinigin and A. Aleksandrov (1990) showed that the use of solar installations for year-round hot water supply to buildings is economically feasible for almost the entire southern part of the Russian Federation.

In recent years, installations with seasonal heat accumulation have been created, which makes it possible, even in Siberian conditions, to save up to 30% of fuel resources and use them to heat small houses in winter. Further searches for the use of solar energy are necessary not only in the southern, but also in the northern regions of Russia, especially considering that such experience already exists in Norway and Finland.

The sun pours an ocean of energy onto the Earth. A person literally swims in this ocean, energy is everywhere. And man, as if not noticing this, digs into the ground for coal and oil in order to extract energy for plants and factories, for lighting and heating. And after all, he extracts all the same energy from the Sun that was “absorbed” by the plants of bygone times, which later became coal. Plants are able to capture less than one percent of the solar energy falling on their leaves, and even less is released after burning coal. Solar energy is available to everyone. There is almost as much of it as you want. It is environmentally friendly - it does not pollute anything, does not violate anything, it gives life to everything that exists on Earth. Moreover, this energy is free, but for all its advantages it is also the most expensive. This is why solar power plants are not as common as other types of power plants.

On the island of Sicily, not far from Mount Etna, famous for its restless nature, a solar power plant with a capacity of 1 MW generated electricity back in the early 80s. The principle of its operation is tower. The mirrors focus the sun's rays on a receiver located at a height of 50 m. There, steam with a temperature of more than 500º C is generated, which drives a traditional turbine with a current generator connected to it. During partly cloudy weather, the lack of solar energy is compensated by a steam accumulator. It has been indisputably proven that power plants with a capacity of 10-20 MW can operate on this principle, as well as much more if similar modules are grouped and connected to each other.

A slightly different type of power plant is in Almeria in southern Spain. Its difference is that

The solar heat focused on the top of the tower sets in motion the sodium cycle (as in

nuclear reactors with fast neutrons), and it already heats the water to form steam. This option has a number of advantages. The sodium heat accumulator provides only continuous operation of the power plant, but makes it possible to partially accumulate excess energy for operation in cloudy weather and at night. The power of the Spanish station is only 0.5 MW. But based on its principle, much larger ones can be created - up to 300 MW. In installations of this type, the concentration of solar energy is so high that the efficiency of the steam turbine process is no worse than in traditional thermal power plants.

This operating principle is embedded in another version of the solar power plant, developed in Germany. Its power is also small - 20 MW. Movable mirrors of 40 m2 each, controlled by a microprocessor, are located around a 200-meter tower. They focus sunlight onto a heater where compressed air is placed. It heats up to 800ºC and drives two gas turbines. Then the heat of the same exhaust air heats up the water, and the steam turbine comes into action. It looks like there are two stages of electricity generation. As a result, the efficiency of the station is increased to 18%, which is significantly more than that of other solar installations.

And in the former USSR, a station with a capacity of 5 MW was built near Kerch. Around the tower, 1,600 mirrors are placed in concentric mirrors, directing the sun's rays to the steam boiler that crowns the 70-meter tower. Mirrors with an area of ​​25 m 2 each, using automation and electric drives, monitor the Sun and reflect solar energy precisely onto the surface of the boiler, providing it with a flux density 150 times greater than the Sun on the surface of the Earth. In the boiler, at a pressure of 40 atmospheres, steam with a temperature of 250ºC is generated and supplied to the steam turbine. Special pressure storage tanks contain water that accumulates heat for work at night and in cloudy weather. Thanks to these batteries, the station can operate for another 3-4 hours after sunset, and at half power – for about half a day.

Solar energy is also used in small solar-powered cars, space stations and satellites.

Work is underway, assessments are underway. So far, it must be admitted, they are not in favor of solar power plants: today these structures are still among the most complex and most expensive technical methods for producing solar energy. But a situation in the world may arise where the relative high cost of solar energy will not be its biggest drawback. We are talking about “thermal pollution” of the planet due to the gigantic scale of energy consumption. Irreversible consequences, scientists say, will occur if energy consumption exceeds current levels by a hundred times. This cannot be overlooked. The scientists’ conclusion is this: at a certain stage in the development of civilization, large-scale use of environmentally friendly solar energy becomes completely necessary. But this does not mean that solar energy does not have opponents. Here are their reasons: due to the low density of solar radiation, the installation of equipment to capture it will lead to the withdrawal of huge usable areas from land use, not counting the extreme high cost of equipment and materials.

In the meantime, there is still a long way to go before it is possible to generate electricity from the sun's rays that is comparable in cost to that produced by burning traditional fossil fuels. Of course, in such conditions it is unrealistic to expect to transfer the entire energy sector to solar technology, even in the foreseeable future. For now, its destiny is to increase capacity and reduce the cost of its kilowatt-hour. At the same time, we should not forget that from an environmental point of view, solar energy is truly ideal, since it does not upset the balance in nature.

The Sun has done a great job of sending its energy to us, so let's appreciate it! A warm ray of light on the face that was on the surface of the Sun eight minutes and nineteen seconds ago

1 . INdry clothes

The Sun has done a great job of sending its energy to us, so let's appreciate it! A warm ray of light on the face was on the surface of the Sun eight minutes and nineteen seconds ago. At a minimum, we use it to dry clothes. Since the sun is a giant nuclear reactor, tell your friends: you have a nuclear clothes dryer.

2 . INsRAWithTAndTb WithVOYu edat

Take away the sun and what can grow? With just soil and sunlight, we can grow tomatoes, peppers, apples, raspberries, green salad and much more. Build solar greenhouses that store the heat of the sun so you can grow food even during the cold winter.

3 . NAGReTb VOdat

Seventy million Chinese households use the sun to heat their water, so why not? You can use an vacuum tube or flat plate to collect the sun's heat. For an investment of approximately $6,800, these units will provide 100 percent hot water in the summer, and 40 percent in the winter.

4 . ABOUThAndWithTAndTb VOdat

If your local water supply is unsafe, you can use the sun to disinfect water by filling plastic bottles and leaving them in the sun for at least six hours. The sun's ultraviolet rays will kill all bacteria and microorganisms. If you live by the sea, you can use solar energy to desalinate your water.

5 . WITHOsubmit youre uhleToTRAndheWithTVO

Install solar panels on the roof.

6. Set the car in motione

Imagine a car that is powered only by the sun. A Nissan Leaf EV 16,000 kilometers per year, for example, will use 2,000 kW of electricity. A photovoltaic system on your roof will generate 2,200 kWh per year, and once you've paid off the solar panels, the energy is free.

7 . DlI dAndhaina yoursO dOmA

When designing a passive solar home, south-facing windows and north-facing insulation create thermal mass to store solar heat. These steps can reduce heating needs by 50 percent. Maximizing natural sunlight reduces the need for artificial lighting.

8. For heating the house

9. Cook food

There are different types of solar cookers: some use reflective solar windows, others use parabolic disks. In summer, you can also make your own solar dryer for fruits and vegetables in your garden.

10. Energy for the world

Every day, the sun emits a thousand times more heat into the world's deserts than we use. Solar thermal technology, using parabolic or solar towers, can convert this energy into steam and then electricity. We could solve all of the world's energy needs using just five percent of Texas for solar thermal energy. So who needs oil and oil spills?

Olya Chernyshova, 8th grade student

Report on physics in 8th grade.

Download:

Preview:

Report on the topic:

"Use of solar energy on Earth."

Completed by an 8th grade student of the Rostoshinskaya Secondary School.

Chernyshova Olga

“First a surgeon, and then the captain of several ships,” Lemuel Gulliver, on one of his travels, ended up on a flying island - Laputa. Entering one of the abandoned houses in Laga Do, the capital of Laputia, he discovered a strange, emaciated man with a sooty face. His dress, shirt and skin were blackened by soot, his disheveled hair and beard were singed in places. This incorrigible projector spent eight years developing a project to extract sunlight from cucumbers. He intended to collect these rays in hermetically sealed bottles so that in case of a cold or rainy summer he could heat the air with them. He expressed confidence that in another eight years he would be able to supply sunlight wherever it was needed.

Today's sun ray catchers are not at all like the madman depicted in Jonathan Swift's fantasy, although they are doing essentially the same thing as Swift's hero - trying to catch the sun's rays and find energetic use for them.

Already the most ancient people thought that all life on Earth was generated and inextricably linked with the Sun. In the religions of the various peoples inhabiting the Earth, one of the most important gods has always been the Sun God, who gives life-giving warmth to all things.

Indeed, the amount of energy coming to Earth from the star closest to us is enormous. In just three days, the Sun sends the Earth as much energy as is contained in all the fuel reserves we have explored! And although only a third of this energy reaches the Earth - the remaining two-thirds are reflected or scattered by the atmosphere - even this part of it is more than one and a half thousand times greater than all other sources of energy used by man combined! And in general, all sources of energy available on Earth are generated by the Sun.

Ultimately, it is to solar energy that man owes all his technical achievements. Thanks to the sun, the water cycle occurs in nature, streams of water are formed that rotate water wheels. By heating the earth differently in different parts of our planet, the sun causes air movement, the same wind that fills the sails of ships and rotates the blades of wind turbines. All fossil fuels used in modern energy come from the sun's rays. It was their energy that, with the help of photosynthesis, was converted by plants into green mass, which, as a result of long processes, turned into oil, gas, and coal.

Is it possible to use the sun's energy directly? At first glance, this is not such a difficult task. Who hasn’t tried to burn a picture onto a wooden board on a sunny day using an ordinary magnifying glass! A minute or two - and on the surface of the tree in the place where the magnifying glass collected the sun's rays, a black dot and light smoke appear. It was in this way that one of Jules Verne’s most beloved heroes, engineer Cyrus Smith, helped out his friends when their fire went out when they found themselves on a mysterious island. The engineer made a lens from two watch glasses, the space between which was filled with water. A homemade “lentil” focused the sun’s rays on an armful of dry moss and ignited it. People have known this relatively simple way of obtaining high temperature since ancient times. In the ruins of the ancient capital of Nineveh in Mesopotamia, primitive lenses made in the 12th century BC were found. Only “pure” fire, obtained directly from the rays of the sun, was supposed to light the sacred fire in the ancient Roman temple of Vesta. It is interesting that ancient engineers suggested another idea for concentrating the sun’s rays - with the help of mirrors. The great Archimedes left us a treatise “On Incendiary Mirrors”. A poetic legend told by the Byzantine poet Tsetses is associated with his name. During the Punic Wars, Archimedes' hometown of Syracuse was besieged by Roman ships. Fleet commander Marcellus had no doubt about an easy victory - after all, his army was much stronger than the city’s defenders. The arrogant naval commander did not take into account one thing - a great engineer entered the fight against the Romans. He came up with formidable fighting machines, built throwing weapons that showered Roman ships with a hail of stones or pierced the bottom with a weighty beam. Other machines used hooked cranes to lift ships by the bow and smash them against the coastal rocks. And one day the Romans were amazed to see that the place of soldiers on the wall of the besieged city was taken by women with mirrors in their hands. At the command of Archimedes, they directed the sunbeams to one ship, to one point. A short time later, a fire broke out on the ship. The same fate befell several more ships of the attackers, until they ran further away in confusion, beyond the reach of the formidable weapon. For many centuries, this story was considered a beautiful fiction. However, some modern researchers of the history of technology have carried out calculations from which it follows that Archimedes’ incendiary mirrors could, in principle, exist

Solar collectors

Our ancestors used solar energy for more prosaic purposes. In Ancient Greece and Ancient Rome, the main tract of forests was rapaciously cut down for the construction of buildings and ships. Wood was hardly used for heating. Solar energy was actively used to heat residential buildings and greenhouses. Architects tried to build houses so that in winter they would receive as much sunlight as possible. The ancient Greek playwright Aeschylus wrote that civilized peoples differ from barbarians in that their houses “face the sun.” The Roman writer Pliny the Younger pointed out that his house, located north of Rome, “collected and increased the heat of the sun due to the fact that its windows were located so as to catch the rays of the low winter sun.” Excavations of the ancient Greek city of Olynthos showed that the entire city and its the houses were designed according to a single plan and were located so that in winter they could catch as much sun rays as possible, and in summer, on the contrary, avoid them. Living rooms were necessarily located with windows facing the sun, and the houses themselves had two floors: one for summer, the other for winter. In Olynthos, as later in Ancient Rome, it was forbidden to place houses so that they shaded the houses of their neighbors from the sun - an ethics lesson for today's skyscraper creators!

The apparent ease of obtaining heat with concentrated sunlight has more than once given rise to unjustified optimism. A little over a hundred years ago, in 1882, the Russian magazine Tekhnik published a note on the use of solar energy in a steam engine: “An insolator is a steam engine whose boiler is heated with the help of solar rays collected for this purpose by a specially designed reflective mirror. The English scientist John Tyndall used similar conical mirrors of very large diameter when studying the heat of lunar rays. French professor A.-B. Mouchot took advantage of Tyndall's idea, applying it to the sun's rays, and obtained heat sufficient to generate steam. The invention, improved by the engineer Pif, was brought to such perfection that the issue of using solar heat can be considered finally resolved in a positive sense.” The optimism of the engineers who built the “insolator” turned out to be unjustified. Scientists still had to overcome too many obstacles for the energy use of solar heat to become a reality. Only now, more than a hundred years later, a new scientific discipline has begun to take shape, dealing with the problems of energy use of solar energy - solar energy. And only now can we talk about the first real successes in this area. What is the difficulty? First of all, here's the thing. With the total enormous energy coming from the sun, each square meter of the earth's surface accounts for very little - from 100 to 200 watts, depending on geographic coordinates. During sunshine hours, this power reaches 400-900 W/m2, and therefore, in order to obtain noticeable power, it is necessary to first collect this flow from a large surface and then concentrate it. And of course, a big inconvenience is the obvious fact that you can only receive this energy during the day. At night you have to use other sources of energy or somehow accumulate solar energy.

Solar desalination plant

You can capture the sun's energy in different ways. The first way is the most direct and natural: use solar heat to heat some coolant. Then the heated coolant can be used, say, for heating or hot water supply (a particularly high water temperature is not needed here), or to produce other types of energy, primarily electrical. The trap for direct use of solar heat is quite simple. To make it, you will first need a box covered with ordinary window glass or similar transparent material. Window glass does not interfere with the sun's rays, but retains the heat that has heated the inner surface of the box. This is, in essence, the greenhouse effect, the principle on which all greenhouses, greenhouses, greenhouses and winter gardens are built. “Small” solar energy is very promising. There are many places on earth where the sun mercilessly beats down from the sky, drying out the soil and burning out vegetation, turning the area into a desert. In principle, it is possible to make such land fertile and inhabitable. We “only” need to provide it with water and build villages with comfortable houses. All this will require, first of all, a lot of energy. To receive this energy from the same withering, destructive sun, turning the sun into a human ally, is a very important and interesting task.

In our country, such work was headed by the Institute of Solar Energy of the Academy of Sciences of the Turkmen SSR, the head of the scientific and production association “Sun”. It is absolutely clear why this institution with a name that seems to have come out of the pages of a science fiction novel is located precisely in Central Asia - after all, in Ashgabat on a summer afternoon, a flow of solar energy falls on every square kilometer, the power equivalent to a large power plant! First of all, scientists directed their efforts to obtain water using solar energy. There is water in the desert, and it is relatively easy to find it - it is located shallow. But this water cannot be used - there are too many various salts dissolved in it, it is usually even more bitter than sea water. To use desert subsoil water for irrigation and drinking, it must be desalinated. If this has been achieved, we can assume that the man-made oasis is ready: here you can live in normal conditions, graze sheep, grow gardens, all year round - there is enough sun even in winter. According to scientists, seven thousand such oases can be built in Turkmenistan alone. All the necessary energy for them will be provided by the sun. The principle of operation of a solar desalination plant is very simple. This is a vessel with water saturated with salts, closed with a transparent lid. The water is heated by the sun's rays, gradually evaporates, and the steam condenses on the cooler lid. Purified water (the salts have not evaporated!) flows from the lid into another vessel.

Constructions of this type have been known for quite some time. The richest deposits of saltpeter in the arid regions of Chile were almost not developed in the last century due to the lack of drinking water. Then, in the town of Las Sali-nas, a desalination plant with an area of ​​5 thousand square meters was built according to this principle, which on a hot day produced 20 thousand liters of fresh water.

But only now work on the use of solar energy for desalination of water has developed on a wide front. For the first time in the world, the Turkmen state farm “Bakharden” launched a real “solar water supply”, which meets people’s needs for fresh water and provides water for irrigation of arid lands. Millions of liters of desalinated water obtained from solar installations will greatly expand the boundaries of state farm pastures.

People spend a lot of energy on winter heating of homes and industrial buildings, and on year-round provision of hot water supply. And here the sun can come to the rescue. Solar power plants have been developed that can provide hot water to livestock farms. The solar trap, developed by Armenian scientists, is very simple in design. This is a rectangular one and a half meter cell in which, under a special coating that effectively absorbs heat, there is a wave-shaped radiator made of a pipe system. One has only to connect such a trap to the water supply and expose it to the sun, and on a summer day, up to thirty liters of water heated to 70-80 degrees will flow out of it per hour. The advantage of this design is that the cells can be used to build a variety of installations, like cubes, greatly increasing the performance of the solar heater. Experts plan to switch an experimental residential area of ​​Yerevan to solar heating. Devices for heating water (or air), called solar collectors, are produced by our industry. Dozens of solar installations and hot water supply systems with a capacity of up to 100 tons of hot water per day have been created to supply a wide variety of facilities.

Solar heaters are installed on numerous houses built in various places in our country. One of the sides of the steep roof, facing the sun, consists of solar heaters, with the help of which the house is heated and supplied with hot water. It is planned to build entire villages consisting of such houses. It is not only in our country that the problem of using solar energy is being addressed. First of all, scientists from countries located in the tropics, where there are many sunny days a year, became interested in solar energy. In India, for example, they have developed an entire program for the use of solar energy. The country's first solar power plant is operating in Madras. In the laboratories of Indian scientists, experimental desalination plants, grain dryers and water pumps are operating. The University of Delhi has built a solar refrigeration unit that can cool food down to 15 degrees below zero. So the sun can not only heat, but also cool! In India's neighboring Burma, students from the Institute of Technology in Rangoon have built a cookstove that uses solar heat to cook food. Even in Czechoslovakia, located much further north, there are now 510 solar heating installations in operation. The total area of ​​their operating sewers is twice the size of a football field! The sun's rays provide warmth to kindergartens and livestock farms, outdoor swimming pools and individual houses. In the city of Holguin, Cuba, an original solar installation developed by Cuban specialists went into operation. It is located on the roof of a children's hospital and provides hot water even on days when the sun is obscured by clouds. According to experts, such installations, which have already appeared in other Cuban cities, will help save a lot of fuel. Construction of a “solar village” has begun in the Algerian province of M’sila. The residents of this rather large settlement will receive all their energy from the sun. Each residential building in this village will be equipped with a solar collector. Separate groups of solar collectors will provide energy to industrial and agricultural facilities. Specialists from the National Scientific Research Organization of Algeria and the United Nations University, who designed this village, are confident that it will become the prototype of thousands of similar settlements in hot countries. The right to be called the first solar settlement is being challenged by an Algerian village by the Australian town of White Cliffs, which became the site of the construction of the original solar power plant. The principle of using solar energy is special here. Scientists at the National University in Canberra have proposed using solar heat to decompose ammonia into hydrogen and nitrogen. If these components are allowed to recombine, heat is released, which can be used to operate a power plant in the same way as the heat produced by burning conventional fuel. This method of using energy is especially attractive because the energy can be stored for future use in the form of unreacted nitrogen and hydrogen and used at night or on stormy days.

Installation of heliostats at the Crimean solar power plant

The chemical method of generating electricity from the sun is generally quite tempting. When used, solar energy can be stored for future use, stored like any other fuel. An experimental installation operating on this principle was created in one of the research centers in Germany. The main component of this installation is a parabolic mirror with a diameter of 1 meter, which, using complex tracking systems, is constantly directed towards the sun. At the focus of the mirror, concentrated solar rays create a temperature of 800-1000 degrees. This temperature is sufficient for the decomposition of sulfuric anhydride into sulfur dioxide and oxygen, which are pumped into special containers. If necessary, the components are fed into a regeneration reactor, where, in the presence of a special catalyst, the original sulfuric anhydride is formed from them. In this case, the temperature rises to 500 degrees. The heat can then be used to turn water into steam, which rotates the turbine of an electric generator. Scientists at the G. M. Krzhizhanovsky Energy Institute are conducting experiments right on the roof of their building in not-so-sunny Moscow. A parabolic mirror, concentrating the sun's rays, heats the gas placed in a metal cylinder to 700 degrees. Hot gas can not only turn water into steam in a heat exchanger, which will drive a turbogenerator. In the presence of a special catalyst, along the way it can be converted into carbon monoxide and hydrogen-energy products that are much more favorable than the original ones. When heating water, these gases do not disappear - they simply cool down. They can be burned and receive additional energy, even when the sun is covered by clouds or at night. Projects are being considered for using solar energy to accumulate hydrogen - supposedly the universal fuel of the future. To do this, you can use the energy obtained from solar power plants located in deserts, that is, where it is difficult to use energy locally.

There are also quite unusual ways. Sunlight itself can split a water molecule if the right catalyst is present. Even more exotic are the existing projects for large-scale hydrogen production using bacteria! The process follows the scheme of photosynthesis: sunlight is absorbed, for example, by blue-green algae, which grow quite quickly. These algae can serve as food for some bacteria, which release hydrogen from the water during their life. Studies conducted by Soviet and Japanese scientists with different types of bacteria have shown that, in principle, all the energy of a city with a million population can be provided by hydrogen released by bacteria feeding on blue-green algae on a plantation with an area of ​​only 17.5 square kilometers. According to calculations by specialists from Moscow State University, a body of water the size of the Aral Sea can provide energy to almost our entire country. Of course, such projects are still far from being implemented. This ingenious idea, even in the 21st century, will require solving many scientific and engineering problems for its implementation. Using living beings instead of huge machines to generate energy is an idea worth racking your brains about.

Power plant projects, where a turbine will rotate steam obtained from water heated by the sun's rays, are now being developed in a variety of countries. In the USSR, an experimental solar power plant of this type was built on the sunny coast of Crimea, near Kerch. The location for the station was not chosen by chance - after all, in this area the sun shines for almost two thousand hours a year. In addition, it is also important that the lands here are saline, not suitable for agriculture, and the station occupies a fairly large area.

The station is an unusual and impressive structure. A solar steam generator boiler is installed on a huge tower, more than eighty meters high. And around the tower, on a vast area with a radius of more than half a kilometer, heliostats are located in concentric circles - complex structures, the heart of each of which is a huge mirror with an area of ​​more than 25 square meters. The station's designers had to solve a very difficult problem - after all, all the heliostats (and there are a lot of them - 1600!) had to be positioned so that no matter the position of the sun in the sky, none of them would be in the shadow, and the sunbeam cast by each of them would fall exactly at the top of the tower, where the steam boiler is located (that’s why the tower is made so high). Each heliostat is equipped with a special device for rotating the mirror. The mirrors must move continuously following the sun - after all, it moves all the time, which means that the bunny can move and not hit the boiler wall, and this will immediately affect the operation of the station. Further complicating the station's work is that the heliostats' trajectories change every day: the Earth moves in orbit and the Sun slightly changes its route across the sky every day. Therefore, control of the movement of heliostats is entrusted to an electronic computer - only its bottomless memory is capable of accommodating the pre-calculated trajectories of movement of all mirrors.

Construction of a solar power plant

Under the influence of solar heat concentrated by heliostats, the water in the steam generator is heated to a temperature of 250 degrees and turns into high-pressure steam. The steam rotates the turbine, which turns the electric generator, and a new stream of energy generated by the sun flows into the energy system of Crimea. Energy production will not stop if the sun is covered by clouds, even at night. Thermal accumulators installed at the foot of the tower will come to the rescue. Excess hot water on sunny days is sent to special storage facilities and will be used when there is no sun.

The power of this experimental power plant is relatively

small - only 5 thousand kilowatts. But let us remember: this was precisely the power of the first nuclear power plant, the ancestor of the mighty nuclear energy industry. And energy production is by no means the most important task of the first solar power station - it is called experimental because with its help scientists will have to find solutions to very complex problems in operating such stations. And many such problems arise. How, for example, can you protect mirrors from contamination? After all, dust settles on them, streaks remain from rain, and this will immediately reduce the power of the station. It even turned out that not all water is suitable for washing mirrors. It was necessary to invent a special washing unit that monitors the cleanliness of the heliostats. At the experimental station, they take an exam on the performance of the device for concentrating solar rays, their most complex equipment. But the longest journey begins with the first step. This step towards generating significant amounts of electricity using the sun will be made possible by the Crimean experimental solar power plant.

Soviet specialists are preparing to take the next step. The world's largest solar power plant with a capacity of 320 thousand kilowatts has been designed. The place was chosen for it in Uzbekistan, in the Karshi steppe, near the young virgin city of Talimarjan. In this region the sun shines no less generously than in Crimea. According to the principle of operation, this station is no different from the Crimean one, but all its structures are much larger. The boiler will be located at a height of two hundred meters, and a heliostatic field will spread around the tower over many hectares. Shiny mirrors (72 thousand!), obeying computer signals, will concentrate the sun's rays on the surface of the boiler, superheated steam will spin the turbine, the generator will produce a current of 320 thousand kilowatts - this is already a lot of power, and prolonged bad weather, preventing energy production at a solar power plant, can have a significant impact on consumers. Therefore, the station design also includes a conventional steam boiler using natural gas. If cloudy weather lasts for a long time, steam will be supplied to the turbine from another, conventional boiler.

Solar power plants of the same type are being developed in other countries. In the USA, in sunny California, the first tower-type power plant, Solar-1, with a capacity of 10 thousand kilowatts, was built. In the foothills of the Pyrenees, French specialists are conducting research at the Themis station with a capacity of 2.5 thousand kilowatts. The GAST station with a capacity of 20 thousand kilowatts was designed by West German scientists.

So far, electrical energy generated by the sun's rays is much more expensive than that obtained by traditional methods. Scientists hope that the experiments they will conduct at pilot installations and stations will help solve not only technical, but also economic problems.

According to calculations, the sun should help solve not only energy problems, but also the tasks that our atomic and space age has set for specialists. To build powerful spaceships, huge nuclear installations, and create electronic machines that perform hundreds of millions of operations per second, we need new

materials - super-refractory, super-strong, super-clean. It's very difficult to get them. Traditional metallurgical methods are not suitable for this. More sophisticated technologies, such as melting with electron beams or ultra-high frequency currents, are also not suitable. But pure solar heat can be a reliable assistant here. When tested, some heliostats easily pierce a thick aluminum sheet with their sunbeams. What if we install several dozen such heliostats? And then send the rays from them onto the concave mirror of the concentrator? The sunbeam of such a mirror can melt not only aluminum, but also almost all known materials. A special melting furnace, where the concentrator will transfer all the collected solar energy, will glow brighter than a thousand suns.

The life of a modern person is simply unthinkable without energy. A power outage seems like a catastrophe; a person can no longer imagine life without transport, and cooking, for example, over a fire rather than on a convenient gas or electric stove is already a hobby.

We still use fossil fuels (oil, gas, coal) to generate energy. But their reserves on our planet are limited, and the day will not come today or tomorrow when they will run out. What to do? The answer already exists - to look for other sources of energy, non-traditional, alternative, the supply of which is simply inexhaustible.

Such alternative energy sources include the sun and wind.

Use of solar energy

Sun- the most powerful energy supplier. We use something due to our physiological characteristics. But millions, billions of kilowatts are wasted and disappear when darkness falls. Every second the Sun gives the Earth 80 thousand billion kilowatts. This is several times more than all the world's power plants produce.

Just imagine what benefits the use of solar energy will bring to humanity:

. Infinity in time. Scientists predict that the Sun will not go out for several billion years. And this means that there will be enough for our lifetime and for our distant descendants.

. Geography. There are no places on our planet where the sun does not shine. Somewhere it is brighter, somewhere it is dimmer, but the Sun is everywhere. This means there will be no need to envelop the Earth in an endless web of wires, trying to deliver electricity to remote corners of the planet.

. Quantity. There is enough solar energy for everyone. Even if someone begins to immeasurably store such energy for future use, it will not change anything. Enough to charge the batteries and sunbathe on the beach.

. Economic benefit. You will no longer need to spend money on buying firewood, coal, or gasoline. Free sunlight will be responsible for the operation of water supply and car, air conditioning and TV, refrigerator and computer.

. Environmentally beneficial. Total deforestation will become a thing of the past, there will be no need to heat furnaces, build new “Chernobyl” and “Fukushima” plants, burn fuel oil and oil. Why put so much effort into destroying nature when there is a wonderful and inexhaustible source of energy in the sky - the Sun.

Fortunately, these are not dreams. Scientists estimate that by 2020, 15% of electricity in Europe will be provided by sunlight. And this is just the beginning.

Where is solar energy used?

. Solar panels. Batteries installed on the roof of a house no longer surprise anyone. By absorbing the sun's energy, they convert it into electricity. In California, for example, any new home project requires the use of a solar panel. And in Holland, the city of Herhugoward is called the “city of the Sun” because all the houses here are equipped with solar panels.

. Transport.

Already now, during autonomous flight, all spacecraft provide themselves with electricity from solar energy.

Solar-powered cars. The first model of such a car was presented back in 1955. And already in 2006, the French company Venturi launched serial production of “solar” cars. Its characteristics are still modest: only 110 kilometers of autonomous travel and a speed of no more than 120 km/h. But almost all world leaders in the automotive industry are developing their own versions of environmentally friendly cars.

. Solar power plants.

. Gadgets. There are already chargers for many devices that run on the sun.

Types of solar energy (solar power plants)

Currently, several types of solar power plants (SPP) have been developed:

. Tower. The operating principle is simple. A huge mirror (heliostat) rotates after the sun and directs the sun's rays to a heat sink filled with water. Then everything happens as in a conventional thermal power plant: water boils and turns into steam. The steam spins a turbine, which powers a generator. The latter generates electricity.

. Disc-shaped. The operating principle is similar to tower ones. The difference lies in the design itself. Firstly, not one mirror is used, but several round ones that look like huge plates. The mirrors are installed radially around the receiver.

Each plate SES can have several similar modules at once.

. Photovoltaic(using photo batteries).

. SES with parabolic cylindrical concentrator. A huge mirror in the shape of a cylinder, where a tube with coolant (most often oil is used) is installed at the focus of the parabola. The oil heats up to the desired temperature and transfers heat to the water.

. Solar-vacuum. The plot of land is covered with a glass roof. The air and soil beneath it heat up more. A special turbine drives warm air to a receiving tower, near which an electric generator is installed. Electricity is generated due to temperature differences.

Use of wind energy

Another type of alternative and renewable energy source is wind. The stronger the wind, the more kinetic energy it produces. And kinetic energy can always be converted into mechanical or electrical energy.

Mechanical energy generated by wind has been used for a long time. For example, when grinding grain (famous windmills) or pumping water.

Wind energy is also used:

In wind turbines that generate electricity. The blades charge the battery, from which current is supplied to the converters. Here the direct current is converted into alternating current.

Transport. There is already a car that runs on wind energy. A special wind installation (kite) allows water vessels to move.

Types of wind energy (wind power plants)

. Ground- the most common type. Such wind farms are installed on hills or hills.

. Offshore. They are built in shallow water, at a considerable distance from the coast. Electricity is supplied to land via undersea cables.

. Coastal- installed at some distance from the sea or ocean. Coastal wind farms use the power of breezes.

. Floating. The first floating wind turbine was installed in 2008 off the coast of Italy. Generators are installed on special platforms.

. Soaring wind farms placed at a height on special pillows made of non-flammable materials and filled with helium. Electricity is supplied to the ground through ropes.

Prospects and development

The most serious long-term plans for the use of solar energy are set by China, which by 2020 plans to become a world leader in this field. The EEC countries are developing a concept that will make it possible to obtain up to 20% of electricity from alternative sources. The US Department of Energy puts a lower figure - up to 14% by 2035. There are SES in Russia too. One of the most powerful is installed in Kislovodsk.

As for the use of wind energy, here are some figures. The European Wind Energy Association has published data showing that wind power plants provide electricity to many countries around the world. Thus, in Denmark, 20% of consumed electricity is obtained through such installations, in Portugal and Spain - 11%, in Ireland - 9%, in Germany - 7%.

Currently, wind farms are installed in more than 50 countries around the world, and their capacity is growing from year to year.

Ministry of Education of the Republic of Belarus

Educational institution

"Belarusian State Pedagogical University named after Maxim Tank"

Department of General and Theoretical Physics

Coursework in general physics

Solar energy and prospects for its use

Students of group 321

Faculty of Physics

Leshkevich Svetlana Valerievna

Scientific adviser:

Fedorkov Cheslav Mikhailovich

Minsk, 2009

Introduction

1. General information about the sun

2. The sun is a source of energy

2.1 Solar energy research

2.2 Solar energy potential

3. Use of solar energy

3.1 Passive use of solar energy

3.2 Active use of solar energy

3.2.1 Solar collectors and their types

3.2.2 Solar systems

3.2.3 Solar thermal power plants

3.3 Photovoltaic systems

4. Solar architecture

Conclusion

List of sources used

Introduction

The sun plays an exceptional role in the life of the Earth. The entire organic world of our planet owes its existence to the Sun. The sun is not only a source of light and heat, but also the original source of many other types of energy (oil, coal, water, wind).

From the moment man appeared on earth, he began to use the energy of the sun. According to archaeological data, it is known that for housing preference was given to quiet places, sheltered from cold winds and open to sunlight.

Perhaps the first known heliosystem can be considered the statue of Amenhotep III, dating back to the 15th century BC. Inside the statue there was a system of air and water chambers, which, under the sun's rays, set a hidden musical instrument in motion. In ancient Greece, Helios was worshiped. The name of this god today forms the basis of many terms associated with solar energy.

The problem of providing electrical energy to many sectors of the world economy and the constantly growing needs of the Earth's population is now becoming more and more urgent.

1. General information about the Sun

The Sun is the central body of the Solar System, a hot plasma ball, a typical dwarf star of spectral class G2.

Characteristics of the Sun

1. Mass MS ~2*1023 kg

2. RS ~629 thousand km

3. V= 1.41*1027 m3, which is almost 1300 thousand times the volume of the Earth,

4. average density 1.41*103 kg/m3,

5. luminosity LS = 3.86*1023 kW,

6. effective surface temperature (photosphere) 5780 K,

7. The rotation period (synodic) varies from 27 days at the equator to 32 days. at the poles,

8. acceleration of gravity 274 m/s2 (with such a huge acceleration of gravity, a person weighing 60 kg would weigh more than 1.5 tons).

Structure of the Sun

In the central part of the Sun there is a source of its energy, or, in figurative language, that “stove” that heats it and does not allow it to cool. This area is called the core (see Fig. 1). In the core, where the temperature reaches 15 MK, energy is released. The core has a radius of no more than a quarter of the total radius of the Sun. However, half of the solar mass is concentrated in its volume and almost all the energy that supports the glow of the Sun is released.

Immediately around the nucleus, a zone of radiative energy transfer begins, where it spreads through the absorption and emission of portions of light - quanta - by the substance. It takes a very long time for a quantum to penetrate through the dense solar matter to the outside. So if the “stove” inside the Sun suddenly went out, we would only know about it millions of years later.

Rice. 1 Structure of the Sun

On its way through the inner solar layers, the energy flow encounters a region where the opacity of the gas greatly increases. This is the convective zone of the Sun. Here energy is transferred not by radiation, but by convection. The convective zone begins at approximately 0.7 radius from the center and extends almost to the most visible surface of the Sun (photosphere), where the transfer of the main energy flow again becomes radiant.

The photosphere is the radiating surface of the Sun, which has a grainy structure called granulation. Each such “grain” is almost the size of Germany and represents a stream of hot substance that has risen to the surface. In the photosphere you can often see relatively small dark areas - sunspots. They are 1500˚C colder than the surrounding photosphere, whose temperature reaches 5800˚C. Due to the temperature difference with the photosphere, these spots appear completely black when observed through a telescope. Above the photosphere is the next, more rarefied layer, called the chromosphere, that is, the “colored sphere”. The chromosphere received this name due to its red color. And finally, above it there is a very hot, but also extremely rarefied part of the solar atmosphere - the corona.

2. The sun is a source of energy

Our Sun is a huge luminous ball of gas, within which complex processes take place and, as a result, energy is continuously released. The energy of the Sun is the source of life on our planet. The sun heats the atmosphere and surface of the Earth. Thanks to solar energy, winds blow, the water cycle occurs in nature, seas and oceans heat up, plants develop, and animals have food. It is thanks to solar radiation that fossil fuels exist on Earth. Solar energy can be converted into heat or cold, motive power and electricity.

The sun evaporates water from the oceans, seas, and from the earth's surface. It turns this moisture into water droplets, forming clouds and fogs, and then causes it to fall back to Earth in the form of rain, snow, dew or frost, thus creating a giant moisture cycle in the atmosphere.

Solar energy is the source of the general circulation of the atmosphere and the circulation of water in the oceans. It seems to create a gigantic system of water and air heating of our planet, redistributing heat over the earth’s surface.

Sunlight, falling on plants, causes the process of photosynthesis, determines the growth and development of plants; getting on the soil, it turns into heat, heats it, forms the soil climate, thereby giving vitality to plant seeds, microorganisms and living creatures inhabiting it, which without this heat would be in a state of anabiosis (hibernation).

The sun emits a huge amount of energy - approximately 1.1x1020 kWh per second. A kilowatt hour is the amount of energy required to operate a 100-watt incandescent light bulb for 10 hours. The Earth's outer atmosphere intercepts approximately one millionth of the energy emitted by the Sun, or approximately 1,500 quadrillion (1.5 x 1018) kWh annually. However, only 47% of all energy, or approximately 700 quadrillion (7 x 1017) kWh, reaches the Earth's surface. The remaining 30% of solar energy is reflected back into space, approximately 23% evaporates water, 1% energy comes from waves and currents and 0.01% from the process of photosynthesis in nature.

2.1 Solar energy research

Why does the Sun shine and not cool down for billions of years? What “fuel” gives it energy? Scientists have been looking for answers to this question for centuries, and only at the beginning of the 20th century was the correct solution found. It is now known that, like other stars, it shines due to thermonuclear reactions occurring in its depths.

If the nuclei of atoms of light elements merge into the nucleus of an atom of a heavier element, then the mass of the new one will be less than the total mass of those from which it was formed. The remainder of the mass is converted into energy, which is carried away by particles released during the reaction. This energy is almost completely converted into heat. This reaction of fusion of atomic nuclei can only occur at very high pressure and temperature above 10 million degrees. That's why it's called thermonuclear.

The main substance that makes up the Sun is hydrogen, which accounts for about 71% of the total mass of the star. Almost 27% belongs to helium, and the remaining 2% comes from heavier elements such as carbon, nitrogen, oxygen and metals. The main “fuel” of the Sun is hydrogen. From four hydrogen atoms, as a result of a chain of transformations, one helium atom is formed. And from every gram of hydrogen participating in the reaction, 6x1011 J of energy are released! On Earth, this amount of energy would be enough to heat 1000 m3 of water from a temperature of 0º C to the boiling point.

2.2 Solar energy potential

The sun provides us with 10,000 times more free energy than is actually used worldwide. Just under 85 trillion (8.5 x 1013) kWh of energy per year is bought and sold in the global commercial market alone. Because it is impossible to monitor the entire process, it is impossible to say with certainty how much non-commercial energy people consume (for example, how much wood and fertilizer is collected and burned, how much water is used to produce mechanical or electrical energy). Some experts estimate that such non-commercial energy accounts for one-fifth of all energy used. But even if this is so, the total energy consumed by humanity during the year is only approximately one seven-thousandth of the solar energy that hits the Earth's surface during the same period.

In developed countries, such as the USA, energy consumption is approximately 25 trillion (2.5 x 1013) kWh per year, which corresponds to more than 260 kWh per person per day. This figure is the equivalent of running more than one hundred 100 W incandescent light bulbs for a whole day every day. The average US citizen consumes 33 times more energy than an Indian, 13 times more than a Chinese, two and a half times more than a Japanese and twice as much as a Swede.

3. Use of solar energy

Solar radiation can be converted into useful energy using so-called active and passive solar systems. Passive systems are achieved by designing buildings and selecting building materials to make maximum use of solar energy. Active solar systems include solar collectors. Photovoltaic systems are also currently being developed - these are systems that convert solar radiation directly into electricity.

Solar energy is also converted into useful energy indirectly by being transformed into other forms of energy, such as biomass, wind or water energy. The energy of the Sun “controls” the weather on Earth. A large share of solar radiation is absorbed by the oceans and seas, the water in which heats up, evaporates and falls to the ground in the form of rain, “feeding” hydroelectric power stations. The wind required by wind turbines is generated due to non-uniform heating of the air. Another category of renewable energy sources arising from solar energy is biomass. Green plants absorb sunlight, and as a result of photosynthesis, organic substances are formed in them, from which thermal and electrical energy can subsequently be obtained. Thus, wind, water and biomass energy are derivatives of solar energy.

Energy is the driving force of any production. The fact that people had a large amount of relatively cheap energy at their disposal greatly contributed to industrialization and the development of society.

3.1 Passive use of solar energy

solar energy thermal power plant

Passive solar buildings are those that are designed to take maximum account of local climatic conditions, and where appropriate technologies and materials are used to heat, cool and light the building using solar energy. These include traditional building techniques and materials such as insulation, solid floors, and south-facing windows. Such living quarters can be built in some cases at no additional cost. In other cases, additional costs incurred during construction can be offset by a reduction in energy costs. Passive solar buildings are environmentally friendly and contribute to energy independence and an energy-sustainable future.

In a passive solar system, the building structure itself acts as a collector of solar radiation. This definition corresponds to most of the simplest systems where heat is stored in a building thanks to its walls, ceilings or floors. There are also systems that provide special elements for storing heat, built into the structure of the building (for example, boxes with stones or tanks or bottles filled with water). Such systems are also classified as passive solar.

3.2 Active use of solar energy

Active use of solar energy is carried out using solar collectors and solar systems.

3.2.1 Solar collectors and their types

Many solar energy systems are based on the use of solar collectors. The collector absorbs light energy from the Sun and converts it into heat, which is transferred to a coolant (liquid or air) and then used to heat buildings, heat water, generate electricity, dry agricultural products or cook food. Solar collectors can be used in almost all processes that use heat.

The technology for manufacturing solar collectors reached almost modern levels in 1908, when William Bailey of the American Carnegie Steel Company invented a collector with a thermally insulated body and copper tubes. This collector was very similar to a modern thermosiphon system. By the end of World War I, Bailey had sold 4,000 of these manifolds, and the Florida businessman who bought the patent from him had sold nearly 60,000 by 1941.

A typical solar collector stores solar energy in roof-mounted modules of tubes and metal plates, painted black to maximize radiation absorption. They are enclosed in a glass or plastic housing and tilted towards the south to capture maximum sunlight. Thus, the collector is a miniature greenhouse that accumulates heat under a glass panel. Since solar radiation is distributed over the surface, the collector must have a large area.

There are solar collectors of various sizes and designs depending on their application. They can provide households with hot water for laundry, bathing and cooking, or be used to preheat water for existing water heaters. Currently, the market offers many different models of collectors.

Integrated manifold

The simplest type of solar collector is a “capacitive” or “thermosyphon collector”, which received this name because the collector is also a heat storage tank in which a “disposable” portion of water is heated and stored. Such collectors are used to preheat water, which is then heated to the desired temperature in traditional installations, for example, in geysers. In household conditions, preheated water flows into a storage tank. This reduces energy consumption for subsequent heating. This collector is a low-cost alternative to an active solar water heating system that uses no moving parts (pumps), requires minimal maintenance, and has zero operating costs.

Flat-plate collectors

Flat-plate collectors are the most common type of solar collectors used in domestic water heating and heating systems. Typically, this collector is a heat-insulated metal box with a glass or plastic lid, in which a black-painted absorber plate is placed. Glazing can be transparent or matte. Flat-plate collectors typically use frosted, light-only glass with a low iron content (it allows a significant portion of the sunlight entering the collector to pass through). Sunlight hits the heat-receiving plate, and thanks to glazing, heat loss is reduced. The bottom and side walls of the collector are covered with heat-insulating material, which further reduces heat losses.

Flat-plate collectors are divided into liquid and air. Both types of collectors are glazed or unglazed.

Solar tubular evacuated collectors

Traditional, simple flat plate solar collectors were designed for use in regions with warm, sunny climates. They sharply lose efficiency on unfavorable days - in cold, cloudy and windy weather. Moreover, condensation and humidity caused by weather conditions lead to premature wear of internal materials, and this, in turn, leads to deterioration in the performance of the system and its breakdown. These disadvantages are eliminated by using evacuated manifolds.

Evacuated collectors heat water for domestic use where higher temperature water is needed. Solar radiation passes through the outer glass tube, hits the absorber tube and turns into heat. It is transmitted to the fluid flowing through the tube. The collector consists of several rows of parallel glass tubes, each of which is attached to a tubular absorber (instead of an absorber plate in flat-plate collectors) with a selective coating. The heated liquid circulates through the heat exchanger and transfers heat to the water contained in the storage tank.

The vacuum in the glass tube - the best possible thermal insulation for the collector - reduces heat loss and protects the absorber and heat pipe from adverse external influences. The result is excellent performance, superior to any other type of solar collector.

Focusing collectors

Focusing collectors (concentrators) use mirror surfaces to concentrate solar energy onto an absorber, also called a heat sink. The temperature they achieve is significantly higher than flat-plate collectors, but they can only concentrate direct solar radiation, which leads to poor performance in foggy or cloudy weather. The mirror surface focuses sunlight reflected from a large surface onto a smaller absorber surface, thereby achieving a high temperature. Some models concentrate solar radiation at a focal point, while others concentrate the sun's rays along a thin focal line. The receiver is located at the focal point or along the focal line. The coolant fluid passes through the receiver and absorbs heat. Such concentrating collectors are most suitable for regions with high insolation - close to the equator and in desert areas.

There are other inexpensive, technologically simple solar collectors for narrow purposes - solar ovens (for cooking) and solar distillers, which allow you to cheaply obtain distilled water from almost any source.

Solar ovens

They are cheap and easy to make. They consist of a spacious, well-insulated box, lined with light-reflecting material (such as foil), covered with glass and equipped with an external reflector. The black pan serves as an absorber, heating up faster than regular aluminum or stainless steel cookware. Solar ovens can be used to disinfect water by bringing it to a boil.

There are box and mirror (with reflector) solar ovens.

Solar stills

Solar distillers provide cheap distilled water, even from salty or highly polluted water. They are based on the principle of evaporation of water from an open container. A solar distiller uses the sun's energy to speed up this process. It consists of a dark-colored, insulated container with glazing, which is tilted so that condensing fresh water flows into a special container. A small solar distiller - about the size of a kitchen stove - can produce up to ten liters of distilled water on a sunny day.

3.2.2 Solar systems

Solar hot water systems

Hot water is the most common direct application of solar energy. A typical installation consists of one or more collectors in which the liquid is heated by the sun, as well as a tank for storing hot water heated by the heating fluid. Even in regions with relatively little solar radiation, such as Northern Europe, a solar system can provide 50-70% of hot water needs. It is impossible to get more, except through seasonal regulation. In Southern Europe, solar can provide 70-90% of hot water consumption. Heating water using solar energy is a very practical and economical way. While photovoltaic systems achieve efficiencies of 10-15%, thermal solar systems achieve efficiencies of 50-90%. When combined with wood burning stoves, household hot water needs can be met virtually year-round without the use of fossil fuels.

Thermosyphon solar systems

Thermosyphon are solar water heating systems with natural circulation (convection) of coolant, which are used in warm winter conditions (in the absence of frost). Overall these are not the most efficient of solar energy systems, but they do have many advantages from a home building perspective. Thermosiphon circulation of the coolant occurs due to a change in the density of water with a change in its temperature. The thermosiphon system is divided into three main parts:

· flat collector (absorber);

· pipelines;

· Storage tank for hot water (boiler).

When the water in the collector (usually a flat one) heats up, it rises through the riser and enters the storage tank; In its place, cold water enters the collector from the bottom of the storage tank. Therefore, it is necessary to place the collector below the storage tank and insulate the connecting pipes.

Such installations are popular in subtropical and tropical areas.

Solar water heating systems

Most often used to heat swimming pools. Although the cost of such an installation varies depending on the size of the pool and other specific conditions, when solar systems are installed to reduce or eliminate fuel or electricity consumption, they will pay for themselves in two to four years through energy savings. Moreover, heating the pool allows you to extend the swimming season by several weeks without additional costs.

It is not difficult to install a solar pool heater in most buildings. It can come down to a simple black hose that supplies water to the pool. For outdoor pools you just need to install an absorber. Indoor pools require the installation of standard collectors to provide warm water even in winter.

Seasonal heat storage

There are also installations that allow you to use in winter the heat accumulated in the summer by solar collectors and stored using large storage tanks (seasonal storage). The problem here is that the amount of liquid required to heat the house is comparable to the volume of the house itself. In addition, the heat storage must be very well insulated. For a typical home storage tank to retain most of its heat for six months, it would have to be wrapped in a layer of insulation 4 meters thick. Therefore, it is advantageous to make the volume of the storage tank very large. Because of this, the ratio of surface area to volume decreases.

Large solar district heating installations are used in Denmark, Sweden, Switzerland, France and the USA. Solar modules are installed directly on the ground. Without storage, such a solar heating installation can cover about 5% of the annual heat demand, since the installation must not produce more than the minimum amount of heat consumed, including losses in the district heating system (up to 20% during transmission). If there is storage of daytime heat at night, then a solar heating system can cover 10-12% of heat demand, including transmission losses, and with seasonal heat storage - up to 100%. There is also the possibility of combining district heating with individual solar collectors. The district heating system can be turned off in the summer, when hot water is provided by the sun and there is no need for heating.

Solar energy combined with other renewable sources.

A good result comes from combining various renewable energy sources, for example, solar heat combined with seasonal heat storage in the form of biomass. Or, if the remaining energy requirement is very low, liquid or gaseous biofuels can be used in combination with efficient boilers to supplement solar heating.

An interesting combination is solar heating and solid biomass boilers. This also solves the problem of seasonal storage of solar energy. Using biomass in summer is not an optimal solution, since the efficiency of boilers at partial load is low, and losses in the pipes are relatively high - and in small systems, burning wood in summer can cause inconvenience. In such cases, 100% of the summer heat load can be provided by solar heating. In winter, when the amount of solar energy is negligible, almost all the heat is generated by burning biomass.

Central Europe has extensive experience in combining solar heating and biomass combustion for heat production. Typically, about 20-30% of the total thermal load is covered by the solar system, and the main load (70-80%) is provided by biomass. This combination can be used both in individual residential buildings and in central (district) heating systems. In Central Europe, about 10 m3 of biomass (for example, firewood) is enough to heat a private home, and a solar installation helps save up to 3 m3 of firewood per year.

3.2.3 Solar thermal power plants

In addition to directly using solar heat, in regions with high solar radiation it can be used to generate steam, which turns a turbine and generates electricity. Solar thermal power generation on a large scale is quite competitive. Industrial applications of this technology date back to the 1980s; Since then, the industry has grown rapidly. Currently, US utilities have already installed more than 400 megawatts of solar thermal power plants, which provide electricity to 350,000 people and replace the equivalent of 2.3 million barrels of oil per year. Nine power plants located in the Mojave Desert (in the US state of California) have 354 MW of installed capacity and have accumulated 100 years of industrial operation experience. This technology is so advanced that, according to officials, it can rival traditional power generation technologies in many areas of the United States. Projects to use solar heat to generate electricity are also set to begin soon in other regions of the world. India, Egypt, Morocco and Mexico are developing corresponding programs, and grants for their financing are provided by the Global Environment Facility (GEF). In Greece, Spain and the USA, new projects are being developed by independent power producers.

Based on the method of heat production, solar thermal power plants are divided into solar concentrators (mirrors) and solar ponds.

Solar concentrators

Such power plants concentrate solar energy using lenses and reflectors. Since this heat can be stored, such plants can generate electricity as needed, day or night, in any weather.

Large mirrors - either point or line focus - concentrate the sun's rays to such an extent that water turns into steam, releasing enough energy to spin a turbine. Company "Luz Corp." installed huge fields of such mirrors in the Californian desert. They produce 354 MW of electricity. These systems can convert solar energy into electricity with an efficiency of about 15%.

There are the following types of solar concentrators:

1. Solar parabolic concentrators

2. Dish-type solar installation

3. Tower-type solar power plants with a central receiver.

Sunny Ponds

Neither focusing mirrors nor solar photovoltaic cells can generate energy at night. For this purpose, solar energy accumulated during the day must be stored in heat storage tanks. This process occurs naturally in so-called solar ponds.

Solar ponds have a high concentration of salt in the bottom water layers, a non-convective middle layer of water in which the salt concentration increases with depth, and a convective layer with a low salt concentration at the surface. Sunlight falls on the surface of the pond and heat is retained in the lower layers of water due to the high concentration of salt. Water of high salinity, heated by solar energy absorbed by the bottom of the pond, cannot rise due to its high density. It remains at the bottom of the pond, gradually warming up until it almost boils (while the upper layers of water remain relatively cold). The hot bottom "brine" is used day or night as a heat source, thanks to which a special organic coolant turbine can generate electricity. The middle layer of a solar pond acts as thermal insulation, preventing convection and heat loss from the bottom to the surface. The temperature difference between the bottom and surface of the pond water is sufficient to power the generator. The coolant, passed through pipes through the lower layer of water, is then fed into a closed Rankine system, in which a turbine rotates to produce electricity.

3.3 Photovoltaic systems

Devices for directly converting light or solar energy into electricity are called photovoltaics (in English Photovoltaics, from the Greek photos - light and the name of the unit of electromotive force - volt). The conversion of sunlight into electricity occurs in solar cells made of semiconductor material such as silicon, which produce an electric current when exposed to sunlight. By connecting photovoltaic cells into modules, and those, in turn, with each other, it is possible to build large photovoltaic stations. The largest such station to date is the 5-megawatt Carrisa Plain installation in the US state of California. The efficiency of photovoltaic installations is currently about 10%, but individual photovoltaic cells can reach efficiencies of 20% or more.

Solar photovoltaic systems are simple to operate and have no moving mechanisms, but the photovoltaic cells themselves contain complex semiconductor devices similar to those used to manufacture integrated circuits. The operation of photocells is based on the physical principle in which an electric current arises under the influence of light between two semiconductors with different electrical properties that are in contact with each other. The combination of such elements forms a photovoltaic panel or module. Photovoltaic modules, due to their electrical properties, produce direct current rather than alternating current. It is used in many simple battery-powered devices. Alternating current, on the other hand, changes its direction at regular intervals. This type of electricity is supplied by energy producers and is used to power most modern appliances and electronic devices. In the simplest systems, the direct current of photovoltaic modules is used directly. Where alternating current is needed, an inverter must be added to the system, which converts direct current into alternating current.

In the coming decades, a significant portion of the world's population will become familiar with photovoltaic systems. Thanks to them, the traditional need to build large, expensive power plants and distribution systems will disappear. As the cost of PV cells comes down and the technology improves, several potentially huge markets for PV cells will open up. For example, photocells built into building materials will provide ventilation and lighting to houses. Consumer products - from hand tools to automobiles - will benefit from the use of components containing photovoltaic components. Utilities will also be able to find new ways to use solar cells to meet public needs.

The simplest photovoltaic systems include:

· Solar Pumps - Photovoltaic pumping units are a welcome alternative to diesel generators and hand pumps. They pump water exactly when it is most needed - on a clear sunny day. Solar pumps are easy to install and operate. A small pump can be installed by one person in a couple of hours, and neither experience nor special equipment is needed.

· Photovoltaic systems with battery - the battery is charged from a solar generator, stores energy and makes it available at any time. Even in the most unfavorable conditions and in remote locations, photovoltaic energy stored in batteries can power essential equipment. Thanks to energy storage, photovoltaic systems provide a reliable source of power, day or night, in any weather. Battery-equipped photovoltaic systems power lighting, sensors, audio recording equipment, appliances, telephones, televisions and power tools around the world.

· photovoltaic systems with generators - when electricity is needed continuously or there are periods when more is needed than the photobattery alone can produce, a generator can effectively supplement it. During daytime hours, photovoltaic modules satisfy the daily energy demand and charge the battery. When the battery is discharged, the motor generator turns on and runs until the batteries are recharged. In some systems, a generator supplies power when electricity consumption exceeds the total capacity of the batteries. The engine-generator produces electricity at any time of the day. Thus, it provides an excellent backup power source for backing up PV modules at night or during inclement weather, depending on the vagaries of the weather. On the other hand, the photovoltaic module operates silently, requires no maintenance, and does not emit pollutants into the atmosphere. The combined use of photovoltaic cells and generators can reduce the initial cost of the system. If there is no backup installation, the PV modules and batteries must be large enough to provide power at night.

· photovoltaic systems connected to the grid - in conditions of centralized power supply, a photovoltaic system connected to the grid can provide part of the required load, while the other part comes from the grid. In this case, the battery is not used. Thousands of homeowners around the world use such systems. The energy from photovoltaic cells is either used on site or fed into the grid. When the owner of the system needs more electricity than it produces - for example, in the evening, the increased demand is automatically satisfied by the network. When the system generates more electricity than the household can consume, the excess is sent (sold) to the grid. Thus, the utility network acts as a reserve for the photovoltaic system, as a battery does for an off-grid installation.

· industrial photovoltaic installations - photovoltaic plants operate silently, do not consume fossil fuels and do not pollute air and water. Unfortunately, photovoltaic stations are not yet a very dynamic part of the arsenal of utility networks, which can be explained by their characteristics. With the current method of calculating the cost of energy, solar electricity is still significantly more expensive than the output of traditional power plants. In addition, photovoltaic systems only produce energy during daylight hours and their performance depends on the weather.

4. Solar architecture

There are several main ways to passively use solar energy in architecture. Using them, you can create many different schemes, thereby obtaining a variety of building designs. The priorities when constructing a building with passive solar energy are: good location of the house; a large number of windows facing south (in the Northern Hemisphere) to let in more sunlight in the winter (and conversely, a small number of windows facing east or west to limit the entry of unwanted sunlight in the summer); correct calculation of the thermal load on the interior to avoid unwanted temperature fluctuations and retain heat at night, well-insulated building structure.

The location, insulation, orientation of windows and the thermal load of the rooms must form a single system. To reduce internal temperature fluctuations, insulation should be placed on the outside of the building. However, in areas where internal heating is rapid, where little insulation is required, or where heat capacity is low, the insulation should be on the inside. Then the building design will be optimal for any microclimate. It is also worth noting that the correct balance between the thermal load on the premises and insulation leads not only to energy savings, but also to savings in building materials. Passive solar buildings are an ideal place to live. Here the connection with nature is more fully felt, there is a lot of natural light in such a house, and it saves energy.

Passive use of sunlight provides approximately 15% of the space heating needs of a standard building and is an important source of energy savings. When designing a building, passive solar building principles must be taken into account to maximize the use of solar energy. These principles can be applied anywhere and at virtually no additional cost.

During building design, the use of active solar systems such as solar collectors and photovoltaic panels should also be considered. This equipment is installed on the south side of the building. To maximize heat output in winter, solar collectors in Europe and North America must be installed at an angle greater than 50° from the horizontal plane. Fixed photovoltaic panels receive the greatest amount of solar radiation during the year when the angle of inclination relative to the horizon is equal to the latitude at which the building is located. The pitch of a building's roof and its south orientation are important considerations when designing a building. Solar collectors for hot water supply and photovoltaic panels should be located in close proximity to the place of energy consumption. It is important to remember that the close location of the bathroom and kitchen allows you to save on installing active solar systems (in this case, you can use one solar collector for two rooms) and minimize energy losses for transportation. The main criterion when choosing equipment is its efficiency.

Conclusion

Currently, only a tiny fraction of solar energy is used due to the fact that existing solar cells have a relatively low efficiency and are very expensive to manufacture. However, one should not immediately abandon the practically inexhaustible source of clean energy: according to experts, solar energy alone could cover all conceivable energy needs of humanity for thousands of years to come. It is also possible to increase the efficiency of solar installations several times, and by placing them on the roofs of houses and next to them, we will ensure heating of housing, heating of water and operation of household electrical appliances even in temperate latitudes, not to mention the tropics. For industrial needs that require large amounts of energy, kilometer-long wastelands and deserts can be used, completely covered with powerful solar power plants. But the solar energy industry faces many difficulties with the construction, placement and operation of solar power plants on thousands of square kilometers of the earth's surface. Therefore, the overall share of solar energy has been and will remain quite modest, at least in the foreseeable future.

Currently, new space projects are being developed to study the Sun, observations are being carried out in which dozens of countries take part. Data about the processes occurring on the Sun are obtained using equipment installed on artificial Earth satellites and space rockets, on mountain peaks and in the depths of the oceans.

Much attention should also be paid to the fact that energy production, which is a necessary means for the existence and development of mankind, has an impact on nature and the human environment. On the one hand, heat and electricity have become so firmly established in human life and production activities that people cannot even imagine their existence without it and consume inexhaustible resources as a matter of course. On the other hand, people are increasingly focusing their attention on the economic aspect of energy and demanding environmentally friendly energy production. This indicates the need to resolve a set of issues, including the redistribution of funds to cover the needs of humanity, the practical use of achievements in the national economy, the search and development of new alternative technologies for generating heat and electricity, etc.

Now scientists are studying the nature of the Sun, finding out its influence on the Earth, and working on the problem of using practically inexhaustible solar energy.

List of sources used

Literature

1. The search for life in the solar system: Translation from English. M.: Mir, 1988, p. 44-57

2. Zhukov G.F. General theory of energy.//M: 1995., p. 11-25

3. Dementiev B.A. Nuclear power reactors. M., 1984, p. 106-111

4. Thermal and nuclear power plants. Directory. Book 3. M., 1985, p. 69-93

5. Encyclopedic Dictionary of a Young Astronomer, M.: Pedagogy, 1980, p. 11-23

6. Vidyapin V.I., Zhuravleva G.P. Physics. General theory.//M: 2005, p. 166-174

7. Dagaev M. M. Astrophysics.//M: 1987, p. 55-61

8. Timoshkin S. E. Solar energy and solar batteries. M., 1966, p. 163-194

9. Illarionov A.G. The nature of energy.//M: 1975., p. 98-105