Alternative energy sources: types and uses. Energy and its types

Energy(from Greek energeia – action, activity) is a general measure (quantification) of various forms of motion of matter considered in physics.

According to the concepts of physical science, energy is the ability of a body or object to do work. For a quantitative characteristic of qualitatively different forms of motion and the interactions corresponding to them, various types of energy are introduced. A person in his daily life most often encounters the following types of energy: mechanical, electrical, electromagnetic, thermal, chemical, nuclear, etc.

Kinetic energy- a measure of mechanical motion, equal for a rigid body to half the product of the body's mass and the square of its speed. It includes the mechanical energy of the movement of a particle or body, thermal energy, nuclear energy, etc.

If energy is the result of a change in the relative position of the particles of the system and their position in relation to other bodies, then it is called potential. It includes the energy of masses attracted by the law of universal gravitation, chemical energy, the energy of the position of homogeneous particles, for example, the energy of an elastic deformed body, etc. .

Mechanical energy - energy of mechanical motion and interaction of bodies or their parts. The mechanical energy of a system of bodies is equal to the sum of the kinetic and potential energies of this system. It manifests itself in the interaction, movement of individual bodies or particles.

It includes the energy of translational motion or rotation of the body, the energy of deformation during bending, stretching, compression of elastic bodies (springs). This energy is most widely used in various machines - transport and technological.

Thermal energy - the energy of the chaotic translational and rotational motion of the molecules of matter. For a solid body, this is the vibration energy of atoms in molecules located at the nodes of the crystal lattice.

Thermal energy arises only as a result of the conversion of other types of energy, for example, when various types of fuels are burned, their chemical energy is converted into thermal energy. It is used for heating, carrying out numerous technological processes (heating, melting, drying, evaporation, distillation, etc.).

Electric Energy - the energy of charged particles or bodies (electrons, ions) moving in an orderly manner along a closed electrical circuit.

Electrical energy is used to produce mechanical energy, thermal energy or any other required energy.

Chemical energy - this is the energy "stored" in the atoms of substances, which is released or absorbed during chemical reactions between substances.

Chemical energy is either released as thermal energy during exothermic reactions (such as fuel combustion) or converted into electrical energy in galvanic cells and batteries.

Nuclear power - the internal energy of the atomic nucleus associated with the movement and interaction of the nucleons forming the nucleus. It is released as a result of a nuclear chain reaction of fission of heavy nuclei (nuclear reaction) or during the synthesis of light nuclei (thermonuclear reaction). In the nuclear power industry, only the first method is used so far, because the use of the second is associated with the still unsolved problem of implementing a controlled thermonuclear reaction.

Gravitational energy - the energy of interaction (attraction) between any two bodies and determined by their masses. It is especially noticeable in outer space. In terrestrial conditions, this is, for example, the energy that a body "stores" when it rises to a certain height above the Earth's surface.

The purpose of this article is to reveal the essence of the concept of "mechanical energy". Physics makes extensive use of this concept both practically and theoretically.

Work and energy

Mechanical work can be determined if the force acting on the body and the displacement of the body are known. There is another way to calculate mechanical work. Consider an example:

The figure shows a body that can be in various mechanical states (I and II). The process of transition of a body from state I to state II is characterized by mechanical work, that is, when moving from state I to state II, the body can perform work. When work is carried out, the mechanical state of the body changes, and the mechanical state can be characterized by one physical quantity - energy.

Energy is a scalar physical quantity of all forms of matter motion and variants of their interaction.

What is mechanical energy

Mechanical energy is a scalar physical quantity that determines the ability of a body to perform work.

A = ∆E

Since energy is a characteristic of the state of the system at a certain point in time, work is a characteristic of the process of changing the state of the system.

Energy and work have the same units of measurement: [A] \u003d [E] \u003d 1 J.

Types of mechanical energy

Mechanical free energy is divided into two types: kinetic and potential.

Kinetic energy- is the mechanical energy of the body, which is determined by the speed of its movement.

E k \u003d 1/2mv 2

Kinetic energy is inherent in moving bodies. When they stop, they perform mechanical work.

In different reference systems, the velocities of the same body at an arbitrary point in time can be different. Therefore, kinetic energy is a relative quantity, it is determined by the choice of a reference frame.

If a force (or several forces simultaneously) acts on a body during movement, the kinetic energy of the body changes: the body accelerates or stops. In this case, the work of the force or the work of the resultant of all forces that are applied to the body will be equal to the difference in kinetic energies:

A = E k1 - E k 2 = ∆E k

This statement and formula was given the name - kinetic energy theorem.

Potential energy called the energy due to the interaction between bodies.

When a body falls m from high h the force of attraction does the work. Since work and energy change are related by an equation, one can write a formula for the potential energy of a body in the gravity field:

Ep = mgh

Unlike kinetic energy E k potential Ep can be negative when h<0 (for example, a body lying at the bottom of a well).

Another type of mechanical potential energy is strain energy. Compressed into distance x spring with stiffness k has potential energy (strain energy):

E p = 1/2 kx 2

The energy of deformation has found wide application in practice (toys), in technology - automata, relays and others.

E = Ep + Ek

full mechanical energy bodies are called the sum of energies: kinetic and potential.

Law of conservation of mechanical energy

Some of the most accurate experiments conducted in the middle of the 19th century by the English physicist Joule and the German physicist Mayer showed that the amount of energy in closed systems remains unchanged. It only passes from one body to another. These studies helped discover law of energy conservation:

The total mechanical energy of an isolated system of bodies remains constant for any interactions of the bodies with each other.

Unlike impulse, which does not have an equivalent form, energy has many forms: mechanical, thermal, energy of molecular motion, electrical energy with the forces of interaction of charges, and others. One form of energy can be converted into another, for example, kinetic energy is converted into thermal energy during the braking of a car. If there are no friction forces, and no heat is generated, then the total mechanical energy is not lost, but remains constant in the process of movement or interaction of bodies:

E = Ep + Ek = const

When the force of friction between bodies acts, then there is a decrease in mechanical energy, however, in this case, it is not lost without a trace, but goes into thermal (internal). If an external force performs work on a closed system, then there is an increase in mechanical energy by the amount of work performed by this force. If a closed system performs work on external bodies, then there is a reduction in the mechanical energy of the system by the amount of work done by it.
Each type of energy can be completely transformed into any other type of energy.

Energy is the ability to do work: move, move objects, produce heat, sound, or electricity.

What is Energy?

Energy is hidden everywhere - in the sun's rays in the form of thermal and light energy, in the player in the form of sound energy, and even in a piece of coal in the form of accumulated chemical energy. We get energy from food, and the car engine extracts it from fuel - gasoline or gas. In both cases, it is chemical energy. There are other forms of energy: thermal, light, sound, electrical, nuclear. Energy is something invisible and intangible, but capable of accumulating and changing from one form to another. She never disappears.

mechanical movement

One of the main types of energy is kinetic - the energy of motion. Heavy objects moving at high speeds carry more kinetic energy than light or slow moving objects. For example, the kinetic energy of a car is less than that of a truck traveling at the same speed.

Thermal energy

Thermal energy cannot exist without kinetic energy. The temperature of a physical body depends on the speed of movement of the atoms of which it consists. The faster the atoms move, the hotter the object will heat up. Therefore, the thermal energy of a body is considered the kinetic energy of its atoms.

Energy cycling

The sun is the main source of energy on Earth. It is constantly being converted into other forms of energy. Natural energy sources also include oil, gas and coal, which, in fact, have a sufficient supply of solar energy.

Stock for the future

Energy can be stored. The spring stores energy when compressed. When released, it straightens up, converting potential energy into kinetic energy. A stone lying on top of a rock also has potential energy; when it falls, it is converted into kinetic energy.

Energy transformation

The Law of Conservation of Energy states that energy never disappears, it just transforms into another form. For example, if a boy riding a bicycle brakes and stops, his kinetic energy drops to zero. But it does not disappear completely, but passes into other types of energy - thermal and sound. The friction of bicycle tires on the ground generates heat, which heats both the ground and the wheels. And sound energy is manifested in the squeak of brakes and tires.

Work, energy and power

The transfer of energy is work. The amount of work done depends on the magnitude of the force and the distance the object is moving. For example, a heavyweight lifting a barbell does a lot of work. The rate at which work is done is called power. The faster the weight lifter lifts the weight, the greater his power. Energy is measured in joules (J) and power in watts (W).

Energy consumption

Energy never disappears, but if it is not used for work, it will be wasted. Most of the energy is wasted on heat production.

For example, an electric light bulb converts only a fifth A of the energy of electricity into light, and the rest goes into unnecessary heat. The low efficiency of automobile engines leads to the fact that a fair amount of fuel is wasted.

The energy of paintball

When playing at the game, the energy constantly changes its state - the potential goes into the kinetic. The moving ball tends to stop due to friction on the automaton part. Its energy is spent on overcoming the force of friction, but does not disappear, but turns into heat. When the player imparts additional energy to the ball with the push of the paddle, the movement of the ball accelerates.

Name the main stages in the history of human energy use, indicate their significance.

What is the relationship between the development of human civilization and energy consumption? Explain the nature of their change over time and indicate trends.

What is an energy system? Its main purpose. What systems are in it?

What are fuel and energy resources? How are they classified?

What are secondary energy resources? Name them and indicate how to obtain them.

What is the energy intensity of primary energy resources? What is the concept of conditional fuel for?

What are the main trends in the global consumption of fuel and energy resources?

What is the essence of the energy crisis of the 70s. in Western Europe and in the 90s. in the CIS countries? What ways do you see for overcoming the energy crisis in Belarus?

How can one explain the intensive use of oil in the global energy balance and what are the future prospects for its use?

Explain the possibilities and prospects for the use of hydrogen in the energy sector.

What is energy efficient technology? What are the motives for their implementation?

Topic 2. Types of energy. Obtaining, converting and using energy Lecture 2. Types of energy. Obtaining, converting and using energy

Basic concepts:

energy; kinetic and potential energy; types of energy; energy; power system; electric power system; energy consumers; traditional and non-traditional energy; load charts; energy consumption per capita; energy intensity of the economy; indicator of the energy-economic level of production.

Energy and its types

Energy is the universal basis of natural phenomena, the basis of culture and all human activity. In the same time underenergy(Greek - action, activity) is understood as a quantitative assessment of various forms of motion of matter, which can turn one into another.

According to the concepts of physical science, energy is the ability of a body or system of bodies to do work. There are various classifications of types and forms of energy. A person in his daily life most often encounters the following types of energy: mechanical, electrical, electromagnetic, thermal, chemical, atomic (intranuclear). The last three types refer to the internal form of energy, i.e. due to the potential energy of the interaction of the particles that make up the body, or the kinetic energy of their random motion.

If energy is the result of a change in the state of motion of material points or bodies, then it is called kinetic ; it includes the mechanical energy of the movement of bodies, thermal energy due to the movement of molecules.

If energy is the result of a change in the relative position of the parts of a given system or its position in relation to other bodies, then it is called potential ; it includes the energy of masses attracted by the law of universal gravitation, the energy of the position of homogeneous particles, for example, the energy of an elastic deformed body, and chemical energy.

Energy in natural science, depending on nature, is divided into the following types.

Mechanical energy - manifests itself in the interaction, movement of individual bodies or particles.

It includes the energy of movement or rotation of the body, the energy of deformation during bending, stretching, twisting, compression of elastic bodies (springs). This energy is most widely used in various machines - transport and technological.

Thermal energy is the energy of disordered (chaotic) motion and interaction of molecules of substances.

Thermal energy, most often obtained by burning various types of fuel, is widely used for heating, carrying out numerous technological processes (heating, melting, drying, evaporation, distillation, etc.).

Electric Energy – the energy of electrons moving through an electrical circuit (electric current).

Electrical energy is used to obtain mechanical energy with the help of electric motors and the implementation of mechanical processes for processing materials: crushing, grinding, mixing; for carrying out electrochemical reactions; obtaining thermal energy in electric heating devices and furnaces; for direct processing of materials (electroerosive processing).

chemical energy – it is the energy "stored" in the atoms of substances, which is released or absorbed during chemical reactions between substances.

Chemical energy is either released in the form of thermal energy during exothermic reactions (for example, fuel combustion), or is converted into electrical energy in galvanic cells and batteries. These energy sources are characterized by high efficiency (up to 98%), but low capacity.

magnetic energy - the energy of permanent magnets, which have a large supply of energy, but "give" it very reluctantly. However, electric current creates extended, strong magnetic fields around itself, therefore, most often they talk about electromagnetic energy.

Electric and magnetic energies are closely interconnected with each other, each of them can be considered as the "reverse" side of the other.

electromagnetic energy is the energy of electromagnetic waves, i.e. moving electric and magnetic fields. It includes visible light, infrared, ultraviolet, x-rays and radio waves.

Thus, electromagnetic energy is the energy of radiation. Radiation carries energy in the form of electromagnetic wave energy. When radiation is absorbed, its energy is converted into other forms, most commonly heat.

Nuclear power - energy localized in the nuclei of atoms of the so-called radioactive substances. It is released during the fission of heavy nuclei (nuclear reaction) or the synthesis of light nuclei (thermonuclear reaction).

There is also an old name for this type of energy - atomic energy, but this name does not accurately reflect the essence of the phenomena that lead to the release of colossal amounts of energy, most often in the form of thermal and mechanical.

Gravitational energy - energy due to the interaction (gravitation) of massive bodies, it is especially noticeable in outer space. In terrestrial conditions, this is, for example, the energy "stored" by a body raised to a certain height above the Earth's surface - the energy of gravity.

Thus, depending on the level of manifestation, one can single out the energy of the macroworld - gravitational, the energy of interaction of bodies - mechanical, the energy of molecularinteractions - thermal, atomic interaction energy - chemical, radiation energy - electromagnetnuyu, the energy contained in the nuclei of atoms - nuclear.

Modern science does not exclude the existence of other types of energy that have not yet been fixed, but do not violate the unified natural-science picture of the world and the concept of energy.

The International System of Units (SI) uses 1 Joule (J) as the unit for measuring energy. 1 J is equivalent to 1 newton meter (Nm). If calculations are related to heat, biological and many other types of energy, then an off-system unit is used as a unit of energy - a calorie (cal) or a kilocalorie (kcal), 1cal = 4.18 J. To measure electrical energy, a unit such as Watt is used. hour (Wh, kWh, MWh), 1 Wh=3.6 MJ. To measure mechanical energy, the value of 1 kg m = 9.8 J is used.

Energy directly extractable from nature(energy of fuel, water, wind, thermal energy of the Earth, nuclear), and which can be converted into electrical, thermal, mechanical, chemical is called primary. In accordance with the classification of energy resources on the basis of exhaustibility, primary energy can also be classified. On fig. 2.1 shows the primary energy classification scheme.

Rice.2.1. Primary Energy Classification

When classifying primary energy, they emit traditional And unconventional types of energy. Traditional types of energy include those types of energy that have been widely used by man for many years. Non-traditional types of energy include those types that have begun to be used relatively recently.

The traditional types of primary energy include: organic fuel (coal, oil, etc.), river hydropower and nuclear fuel (uranium, thorium, etc.).

The energy received by a person, after the conversion of primary energy at special installations - stations, called secondary (electrical energy, steam energy, hot water, etc.).

Advantages of electrical energy. Electrical energy is the most convenient type of energy and can rightly be considered the basis of modern civilization. The overwhelming majority of technical means of mechanization and automation of production processes (equipment, computer devices), the replacement of human labor with machine labor in everyday life, have an electrical basis.

Slightly more than half of all energy consumed is used as heat for technical needs, heating, cooking, the rest - in the form of mechanical, primarily in transport installations, and electrical energy. Moreover, the share of electric energy is growing every year (Fig. 2.2).

Electric Energy - a more versatile form of energy. It has found wide application in everyday life and in all sectors of the national economy. There are more than four hundred types of electrical household appliances: refrigerators, washing machines, air conditioners, fans, televisions, tape recorders, lighting devices, etc. It is impossible to imagine industry without electrical energy. In agriculture, the use of electricity is constantly expanding: feeding and watering animals, caring for them, heating and ventilation, incubators, heaters, dryers, etc.

Electrification - the basis of technical progress of any branch of the national economy. It allows you to replace energy resources that are inconvenient for use with a universal type of energy - electrical energy, which can be transmitted over any distance, converted into other types of energy, for example, mechanical or thermal, and divided between consumers. Electricity - a very convenient and economical form of energy.

Rice. 2.2. Electric energy consumption dynamics

Electrical energy has such properties that make it indispensable in the mechanization and automation of production and in everyday human life:

1. Electrical energy is universal, it can be used for a variety of purposes. In particular, it is very easy to turn it into heat. This is done, for example, in electric light sources (incandescent bulbs), in technological furnaces used in metallurgy, in various heating and heating devices. The conversion of electrical energy into mechanical energy is used in the drives of electric motors.

2. When consuming electrical energy, it can be infinitely crushed. Thus, the power of electrical machines, depending on their purpose, is different: from fractions of a watt in micromotors used in many branches of technology and in household products, to huge values ​​exceeding a million kilowatts in power plant generators.

3. In the process of production and transmission of electrical energy, it is possible to concentrate its power, increase the voltage and transmit through wires both short and long distances any amount of electrical energy from the power plant where it is generated to all its consumers.

In connection with the development of production technologies and a significant deterioration of the environmental situation in many regions of the world, humanity is faced with the problem of finding new sources of energy. On the one hand, the amount of energy produced should be sufficient for the development of production, science and the domestic sector, on the other hand, energy production should not adversely affect the environment.

This formulation of the question led to the search for so-called alternative energy sources - sources that meet the above requirements. Through the efforts of world science, many such sources have been discovered, at the moment most of them are already used more or less widely. Here is a brief overview of them:

solar energy

Solar power plants are actively used in more than 80 countries, they convert solar energy into electrical energy. There are different ways of such conversion and, accordingly, different types of solar power plants. The most common stations that use photoelectric converters (photocells) combined into solar panels. Most of the largest photovoltaic installations in the world are located in the USA.

Wind energy

Wind power plants (wind farms) are widely used in the USA, China, India, as well as in some Western European countries (for example, in Denmark, where 25% of all electricity is produced in this way). Wind energy is a very promising source of alternative energy; at present, many countries are significantly expanding the use of power plants of this type.

biofuel

The main advantages of this energy source over other types of fuel are its environmental friendliness and renewability. Not all types of biofuels are classified as alternative energy sources: traditional firewood is also a biofuel, but it is not an alternative energy source. Alternative biofuels can be solid (peat, woodworking and agricultural waste), liquid (biodiesel and biomasut, as well as methanol, ethanol, butanol) and gaseous (hydrogen, methane, biogas).

Tidal and wave energy

Unlike traditional hydropower, which uses the energy of a water stream, alternative hydropower has not yet become widespread. The main disadvantages of tidal power plants are the high cost of their construction and daily power changes, for which it is advisable to use power plants of this type only as part of power systems that also use other energy sources. The main advantages are high environmental friendliness and low cost of energy production.

Thermal energy of the Earth

To develop this energy source, geothermal power plants are used that use the energy of high-temperature groundwater, as well as volcanoes. At the moment, hydrothermal energy is more common, using the energy of hot underground sources. Petrothermal energy, based on the use of the "dry" heat of the earth's interior, is currently poorly developed; The main problem is the low profitability of this method of energy production.

atmospheric electricity

(Lightning flashes on the surface of the Earth occur almost simultaneously in various places on the planet.)

Thunderstorm energy, based on the capture and accumulation of lightning energy, is still in its infancy. The main problems of thunderstorm energy are the mobility of thunderstorm fronts, as well as the speed of atmospheric electrical discharges (lightning), which makes it difficult to accumulate their energy.