For Russia, the energy of the Earth's heat can become a constant, reliable source of providing cheap and affordable electricity and heat using new high, environmentally friendly technologies for its extraction and supply to the consumer. This is especially true at the moment

Limited resources of fossil energy raw materials

The demand for organic energy raw materials is great in industrialized and developing countries (USA, Japan, states of united Europe, China, India, etc.). At the same time, their own hydrocarbon resources in these countries are either insufficient or reserved, and a country, such as the United States, buys energy raw materials abroad or develops deposits in other countries.

In Russia, one of the richest countries in terms of energy resources, the economic needs for energy are still satisfied by the possibilities of using natural resources. However, the extraction of fossil hydrocarbons from the subsoil occurs at a very fast pace. If in the 1940s-1960s. The main oil-producing regions were the "Second Baku" in the Volga and Cis-Urals, then, starting from the 1970s, and to the present, Western Siberia has been such an area. But even here there is a significant decline in the production of fossil hydrocarbons. The era of "dry" Cenomanian gas is passing away. The previous stage of extensive development of natural gas production has come to an end. Its extraction from such giant deposits as Medvezhye, Urengoyskoye and Yamburgskoye amounted to 84, 65 and 50%, respectively. The proportion of oil reserves favorable for development also decreases over time.

Due to the active consumption of hydrocarbon fuels, onshore reserves of oil and natural gas have been significantly reduced. Now their main reserves are concentrated on the continental shelf. And although the raw material base of the oil and gas industry is still sufficient for the extraction of oil and gas in Russia in the required volumes, in the near future it will be provided to an increasing extent through the development of fields with complex mining and geological conditions. At the same time, the cost of hydrocarbon production will grow.

Most of the non-renewable resources extracted from the subsoil are used as fuel for power plants. First of all, this is the share of which in the fuel structure is 64%.

In Russia, 70% of electricity is generated at thermal power plants. Energy enterprises of the country annually burn about 500 million tons of c.e. tons for the purpose of generating electricity and heat, while the production of heat consumes 3-4 times more hydrocarbon fuel than the generation of electricity.

The amount of heat obtained from the combustion of these volumes of hydrocarbon raw materials is equivalent to the use of hundreds of tons of nuclear fuel - the difference is huge. However, nuclear power requires ensuring environmental safety (to prevent a repeat of Chernobyl) and protecting it from possible terrorist attacks, as well as the safe and costly decommissioning of obsolete and spent nuclear power units. The proven recoverable reserves of uranium in the world are about 3 million 400 thousand tons. For the entire previous period (until 2007), about 2 million tons were mined.

RES as the future of global energy

The increased interest in the world in recent decades in alternative renewable energy sources (RES) is caused not only by the depletion of hydrocarbon fuel reserves, but also by the need to solve environmental problems. Objective factors (fossil fuel and uranium reserves, as well as environmental changes associated with the use of traditional fire and nuclear energy) and energy development trends suggest that the transition to new methods and forms of energy production is inevitable. Already in the first half of the XXI century. there will be a complete or almost complete transition to non-traditional energy sources.

The sooner a breakthrough is made in this direction, the less painful it will be for the whole society and the more beneficial for the country, where decisive steps will be taken in this direction.

The world economy has already set a course for the transition to a rational combination of traditional and new energy sources. Energy consumption in the world by 2000 amounted to more than 18 billion tons of fuel equivalent. tons, and energy consumption by 2025 may increase to 30–38 billion tons of fuel equivalent. tons, according to forecast data, by 2050 consumption at the level of 60 billion tons of fuel equivalent is possible. t. A characteristic trend in the development of the world economy in the period under review is a systematic decrease in the consumption of fossil fuels and a corresponding increase in the use of non-traditional energy resources. The thermal energy of the Earth occupies one of the first places among them.

Currently, the Ministry of Energy of the Russian Federation has adopted a program for the development of non-traditional energy, including 30 large projects for the use of heat pump units (HPU), the principle of operation of which is based on the consumption of low-potential thermal energy of the Earth.

Low-potential energy of the Earth's heat and heat pumps

The sources of low-potential energy of the Earth's heat are solar radiation and thermal radiation of the heated bowels of our planet. At present, the use of such energy is one of the most dynamically developing areas of energy based on renewable energy sources.

The heat of the Earth can be used in various types of buildings and structures for heating, hot water supply, air conditioning (cooling), as well as for heating tracks in the winter season, preventing icing, heating fields in open stadiums, etc. In the English-language technical literature of the system utilizing the Earth's heat in heating and air conditioning systems are referred to as GHP - "geothermal heat pumps" (geothermal heat pumps). The climatic characteristics of the countries of Central and Northern Europe, which, together with the United States and Canada, are the main areas for the use of low-grade heat of the Earth, determine this mainly for heating purposes; cooling of the air, even in summer, is relatively rarely required. Therefore, unlike in the USA, heat pumps in European countries operate mainly in heating mode. In the US, they are more often used in air heating systems combined with ventilation, which allows both heating and cooling of the outside air. In European countries, heat pumps are usually used in water heating systems. Since their efficiency increases as the temperature difference between the evaporator and condenser decreases, floor heating systems are often used for heating buildings, in which a coolant of a relatively low temperature (35–40 ° C) circulates.

Types of systems for the use of low-potential energy of the Earth's heat

In the general case, two types of systems for using the low-potential energy of the Earth's heat can be distinguished:

- open systems: as a source of low-grade thermal energy, groundwater is used, which is supplied directly to heat pumps;

- closed systems: heat exchangers are located in the soil massif; when a coolant with a temperature lower than the ground circulates through them, thermal energy is “taken off” from the ground and transferred to the heat pump evaporator (or when a coolant with a higher temperature relative to the ground is used, it is cooled).

The disadvantages of open systems are that wells require maintenance. In addition, the use of such systems is not possible in all areas. The main requirements for soil and groundwater are as follows:

- sufficient water permeability of the soil, allowing replenishment of water reserves;

– good groundwater chemistry (e.g. low iron content) to avoid pipe scale and corrosion problems.

Closed systems for the use of low-potential energy of the Earth's heat

Closed systems are horizontal and vertical (Figure 1).

Rice. 1. Scheme of a geothermal heat pump installation with: a - horizontal

and b - vertical ground heat exchangers.

Horizontal ground heat exchanger

In the countries of Western and Central Europe, horizontal ground heat exchangers are usually separate pipes laid relatively tightly and connected to each other in series or in parallel (Fig. 2).

Rice. 2. Horizontal ground heat exchangers with: a - sequential and

b - parallel connection.

To save the area of ​​the site where the heat is removed, improved types of heat exchangers have been developed, for example, heat exchangers in the form of a spiral (Fig. 3), located horizontally or vertically. This form of heat exchangers is common in the USA.

Since ancient times, people have known about the spontaneous manifestations of gigantic energy lurking in the bowels of the globe. The memory of mankind keeps legends about catastrophic volcanic eruptions that claimed millions of human lives, unrecognizably changed the appearance of many places on Earth. The power of the eruption of even a relatively small volcano is colossal, it many times exceeds the power of the largest power plants created by human hands. True, there is no need to talk about the direct use of the energy of volcanic eruptions: people do not yet have the opportunity to curb this recalcitrant element, and, fortunately, these eruptions are quite rare events. But these are manifestations of the energy lurking in the bowels of the earth, when only a tiny fraction of this inexhaustible energy finds a way out through the fire-breathing vents of volcanoes.

The small European country of Iceland (“country of ice” in literal translation) is fully self-sufficient in tomatoes, apples and even bananas! Numerous Icelandic greenhouses are powered by the heat of the earth, there are practically no other local sources of energy in Iceland. But this country is very rich hot springs and famous geysers - fountains of hot water, with the precision of a chronometer escaping from the ground. And although Icelanders do not have priority in using the heat of underground sources (even the ancient Romans brought water from under the ground to the famous baths - the baths of Caracalla), the inhabitants of this small northern country operate the underground boiler house very intensively. The capital city of Reykjavik, where half of the country's population lives, is heated only by underground sources. Reykjavik is the ideal starting point for exploring Iceland: from here you can go on the most interesting and varied excursions to any corner of this unique country: geysers, volcanoes, waterfalls, rhyolite mountains, fjords... Everywhere in Reykjavik you will feel PURE ENERGY - the thermal energy of geysers , gushing from underground, the energy of cleanliness and space of an ideally green city, the energy of Reykjavik's fun and incendiary nightlife all year round.

But not only for heating people draw energy from the depths of the earth. Power plants using hot underground springs have been operating for a long time. The first such power plant, still very low-power, was built in 1904 in the small Italian town of Larderello, named after the French engineer Larderelli, who back in 1827 drew up a project for the use of numerous hot springs in the area. Gradually, the capacity of the power plant grew, more and more new units came into operation, new sources of hot water were used, and today the power of the station has already reached an impressive value - 360 thousand kilowatts. In New Zealand, there is such a power plant in the Wairakei region, its capacity is 160,000 kilowatts. A geothermal plant with a capacity of 500,000 kilowatts produces electricity 120 km from San Francisco in the United States.

geothermal energy

Since ancient times, people have known about the spontaneous manifestations of gigantic energy lurking in the bowels of the globe. The memory of mankind keeps legends about catastrophic volcanic eruptions that claimed millions of human lives, unrecognizably changed the appearance of many places on Earth. The power of the eruption of even a relatively small volcano is colossal, it many times exceeds the power of the largest power plants created by human hands. True, there is no need to talk about the direct use of the energy of volcanic eruptions - so far people do not have the opportunity to curb this recalcitrant element, and, fortunately, these eruptions are quite rare events. But these are manifestations of the energy lurking in the bowels of the earth, when only a tiny fraction of this inexhaustible energy finds a way out through the fire-breathing vents of volcanoes.

A geyser is a hot spring that erupts its water at regular or irregular heights, like a fountain. The name comes from the Icelandic word for "pours". The appearance of geysers requires a certain favorable environment, which is created only in a few places on earth, which leads to their rather rare presence. Almost 50% of geysers are located in the Yellowstone National Park (USA). The activity of the geyser may stop due to changes in the bowels, earthquakes and other factors. The action of a geyser is caused by the contact of water with magma, after which the water quickly heats up and, under the influence of geothermal energy, is thrown upward with force. After the eruption, the water in the geyser gradually cools, seeps back to the magma, and again gushing. The frequency of eruptions of various geysers varies from several minutes to several hours. The need for high energy to operate a geyser is the main reason for their rarity. Volcanic areas may have hot springs, mud volcanoes, fumaroles, but there are very few places where geysers are found. The fact is that even if a geyser formed at the site of volcano activity, subsequent eruptions will destroy the surface of the earth and change its state, which will lead to the disappearance of the geyser.

The energy of the earth (geothermal energy) is based on the use of the natural heat of the Earth. The bowels of the Earth are fraught with a colossal, almost inexhaustible source of energy. The annual radiation of internal heat on our planet is 2.8 * 1014 billion kWh. It is constantly compensated by the radioactive decay of some isotopes in the earth's crust.

Geothermal energy sources can be of two types. The first type is underground pools of natural heat carriers - hot water (hydrothermal springs), or steam (steam thermal springs), or a steam-water mixture. In essence, these are directly ready-to-use "underground boilers" from where water or steam can be extracted using ordinary boreholes. The second type is the heat of hot rocks. By pumping water into such horizons, one can also obtain steam or superheated water for further use for energy purposes.

But in both use cases, the main disadvantage is, perhaps, a very low concentration of geothermal energy. However, in places of formation of peculiar geothermal anomalies, where hot springs or rocks come relatively close to the surface and where the temperature rises by 30-40 ° C for every 100 m, concentrations of geothermal energy can create conditions for its economic use. Depending on the temperature of water, steam or steam-water mixture, geothermal sources are divided into low and medium temperature (with temperatures up to 130 - 150 ° C) and high temperature (over 150 °). The nature of their use largely depends on the temperature.

It can be argued that geothermal energy has four beneficial features.

First, its reserves are practically inexhaustible. According to estimates of the late 70s, down to a depth of 10 km, they amount to a value that is 3.5 thousand times greater than the reserves of traditional types of mineral fuel.

Secondly, geothermal energy is quite widespread. Its concentration is associated mainly with belts of active seismic and volcanic activity, which occupy 1/10 of the Earth's area. Within these belts, some of the most promising "geothermal regions" can be distinguished, examples of which are California in the USA, New Zealand, Japan, Iceland, Kamchatka, and the North Caucasus in Russia. Only in the former USSR, by the beginning of the 90s, about 50 underground pools of hot water and steam were opened.

Thirdly, the use of geothermal energy does not require high costs, because. in this case, we are talking about already “ready-to-use”, energy sources created by nature itself.

Finally, fourthly, geothermal energy is environmentally completely harmless and does not pollute the environment.

Man has long been using the energy of the internal heat of the Earth (let us recall the famous Roman baths), but its commercial use began only in the 20s of our century with the construction of the first geoelectric power plants in Italy, and then in other countries. By the beginning of the 1980s, there were about 20 such stations operating in the world with a total capacity of 1.5 million kW. The largest of them is the Geysers station in the USA (500 thousand kW).

Geothermal energy is used to generate electricity, heat homes, greenhouses, etc. Dry steam, superheated water or any heat carrier with a low boiling point (ammonia, freon, etc.) is used as a heat carrier.

Doctor of technical sciences ON THE. I swear, professor,
Academician of the Russian Academy of Technological Sciences, Moscow

In recent decades, the world has been considering the direction of more efficient use of the energy of the deep heat of the Earth in order to partially replace natural gas, oil, and coal. This will become possible not only in areas with high geothermal parameters, but also in any area of ​​the globe when drilling injection and production wells and creating circulation systems between them.

The increased interest in alternative energy sources in the world in recent decades is caused by the depletion of hydrocarbon fuel reserves and the need to solve a number of environmental problems. Objective factors (reserves of fossil fuels and uranium, as well as changes in the environment caused by traditional fire and nuclear power) allow us to assert that the transition to new methods and forms of energy production is inevitable.

The world economy is currently heading towards the transition to a rational combination of traditional and new energy sources. The heat of the Earth occupies one of the first places among them.

Geothermal energy resources are divided into hydrogeological and petrogeothermal. The first of them are represented by heat carriers (comprising only 1% of the total geothermal energy resources) - groundwater, steam and steam-water mixtures. The second are geothermal energy contained in hot rocks.

The fountain technology (self-spill) used in our country and abroad for the extraction of natural steam and geothermal waters is simple, but inefficient. With a low flow rate of self-flowing wells, their heat production can recoup the cost of drilling only at a shallow depth of geothermal reservoirs with high temperatures in areas of thermal anomalies. The service life of such wells in many countries does not even reach 10 years.

At the same time, experience confirms that in the presence of shallow collectors of natural steam, the construction of a Geothermal power plant is the most profitable option for using geothermal energy. The operation of such GeoTPPs has shown their competitiveness in comparison with other types of power plants. Therefore, the use of reserves of geothermal waters and steam hydrotherms in our country on the Kamchatka Peninsula and on the islands of the Kuril chain, in the regions of the North Caucasus, and also possibly in other areas, is expedient and timely. But steam deposits are a rarity, its known and predicted reserves are small. Much more common deposits of heat and power water are not always located close enough to the consumer - the heat supply object. This excludes the possibility of large scales of their effective use.

Often, the issues of combating scaling develop into a complex problem. The use of geothermal, as a rule, mineralized sources as a heat carrier leads to overgrowth of borehole zones with iron oxide, calcium carbonate and silicate formations. In addition, the problems of erosion-corrosion and scaling adversely affect the operation of the equipment. The problem, also, is the discharge of mineralized and wastewater containing toxic impurities. Therefore, the simplest fountain technology cannot serve as the basis for the widespread development of geothermal resources.

According to preliminary estimates on the territory of the Russian Federation, the predicted reserves of thermal waters with a temperature of 40-250 °C, salinity of 35-200 g/l and a depth of up to 3000 m are 21-22 million m3/day, which is equivalent to burning 30-40 million tons of .t. in year.

The predicted reserves of the steam-air mixture with a temperature of 150-250 °C in the Kamchatka Peninsula and the Kuril Islands are 500 thousand m3/day. and reserves of thermal waters with a temperature of 40-100 ° C - 150 thousand m3 / day.

The reserves of thermal waters with a flow rate of about 8 million m3/day, with a salinity of up to 10 g/l and a temperature above 50 °C are considered top priority for development.

Much more important for the energy of the future is the extraction of thermal energy, practically inexhaustible petrogeothermal resources. This geothermal energy, enclosed in solid hot rocks, is 99% of the total resources of underground thermal energy. At a depth of up to 4-6 km, massifs with a temperature of 300-400 °C can be found only near the intermediate chambers of some volcanoes, but hot rocks with a temperature of 100-150 °C are distributed almost everywhere at these depths, and with a temperature of 180-200 °C in a fairly significant part territory of Russia.

For billions of years, nuclear, gravitational and other processes inside the Earth have generated and continue to generate thermal energy. Some of it is radiated into outer space, and heat is accumulated in the depths, i.e. the heat content of the solid, liquid and gaseous phases of terrestrial matter is called geothermal energy.

The continuous generation of intraterrestrial heat compensates for its external losses, serves as a source of accumulation of geothermal energy and determines the renewable part of its resources. The total removal of heat from the interior to the earth's surface is three times higher than the current capacity of power plants in the world and is estimated at 30 TW.

However, it is clear that renewability only matters for limited natural resources, and the total potential of geothermal energy is practically inexhaustible, since it should be defined as the total amount of heat available to the Earth.

It is no coincidence that in recent decades, the world has been considering the direction of more efficient use of the energy of the deep heat of the Earth in order to partially replace natural gas, oil, and coal. This will become possible not only in areas with high geothermal parameters, but also in any area of ​​the globe when drilling injection and production wells and creating circulation systems between them.

Of course, with low thermal conductivity of rocks, for the efficient operation of circulation systems, it is necessary to have or create a sufficiently developed heat exchange surface in the heat extraction zone. Such a surface is often found in porous formations and zones of natural fracture resistance, which are often found at the above depths, the permeability of which makes it possible to organize forced filtration of the coolant with efficient extraction of rock energy, as well as the artificial creation of an extensive heat exchange surface in low-permeable porous massifs by hydraulic fracturing (see figure).

Currently, hydraulic fracturing is used in the oil and gas industry as a way to increase reservoir permeability to enhance oil recovery in the development of oil fields. Modern technology makes it possible to create a narrow but long crack, or a short but wide one. Examples of hydraulic fractures with fractures up to 2-3 km long are known.

The domestic idea of ​​extracting the main geothermal resources contained in solid rocks was expressed as early as 1914 by K.E. Obruchev.

In 1963, the first GCC was created in Paris to extract heat from porous formation rocks for heating and air conditioning in the premises of the Broadcasting Chaos complex. In 1985, 64 GCCs were already operating in France with a total thermal capacity of 450 MW, with an annual saving of approximately 150,000 tons of oil. In the same year, the first such GCC was created in the USSR in the Khankala valley near the city of Grozny.

In 1977, under the project of the Los Alamos National Laboratory of the USA, tests of an experimental GCC with hydraulic fracturing of an almost impermeable massif began at the Fenton Hill site in the state of New Mexico. Cold fresh water injected through the well (injection) was heated due to heat exchange with a rock mass (185 OC) in a vertical fracture with an area of ​​8000 m2, formed by hydraulic fracturing at a depth of 2.7 km. In another well (production), also crossing this crack, superheated water came to the surface in the form of a steam jet. When circulating in a closed circuit under pressure, the temperature of superheated water on the surface reached 160-180 °C, and the thermal power of the system - 4-5 MW. Coolant leaks into the surrounding massif amounted to about 1% of the total flow. The concentration of mechanical and chemical impurities (up to 0.2 g/l) corresponded to the conditions of fresh drinking water. The hydraulic fracture did not require fixing and was kept open by the hydrostatic pressure of the fluid. The free convection developing in it ensured effective participation in the heat exchange of almost the entire surface of the outcrop of the hot rock mass.

The extraction of underground thermal energy from hot impermeable rocks, based on the methods of inclined drilling and hydraulic fracturing that have been mastered and practiced in the oil and gas industry for a long time, did not cause seismic activity or any other harmful effects on the environment.

In 1983, British scientists repeated the American experience by creating an experimental GCC with hydraulic fracturing of granites in Carnwell. Similar work was carried out in Germany, Sweden. More than 224 geothermal heating projects have been implemented in the USA. It is assumed, however, that geothermal resources can provide the bulk of the US's future non-electric thermal energy needs. In Japan, the capacity of GeoTPP in 2000 reached approximately 50 GW.

Currently, research and exploration of geothermal resources is carried out in 65 countries. In the world, based on geothermal energy, stations with a total capacity of about 10 GW have been created. The United Nations is actively supporting the development of geothermal energy.

The experience accumulated in many countries of the world in the use of geothermal coolants shows that under favorable conditions they are 2-5 times more profitable than thermal and nuclear power plants. Calculations show that one geothermal well can replace 158 thousand tons of coal per year.

Thus, the heat of the Earth is, perhaps, the only major renewable energy resource, the rational development of which promises to reduce the cost of energy compared to modern fuel energy. With an equally inexhaustible energy potential, solar and thermonuclear installations, unfortunately, will be more expensive than existing fuel ones.

Despite the very long history of the development of the Earth's heat, today geothermal technology has not yet reached its high development. The development of the thermal energy of the Earth is experiencing great difficulties in the construction of deep wells, which are a channel for bringing the coolant to the surface. Due to the high temperature at the bottomhole (200-250 °C), traditional rock cutting tools are unsuitable for working in such conditions, there are special requirements for the selection of drill and casing pipes, cement slurries, drilling technology, casing and completion of wells. Domestic measuring equipment, serial operational fittings and equipment are produced in a design that allows temperatures not higher than 150-200 ° C. Traditional deep mechanical drilling of wells sometimes drags on for years and requires significant financial costs. In the main production assets, the cost of wells is from 70 to 90%. This problem can and should be solved only by creating a progressive technology for the development of the main part of geothermal resources, i.e. extraction of energy from hot rocks.

Our group of Russian scientists and specialists has been dealing with the problem of extracting and using the inexhaustible, renewable deep thermal energy of the Earth's hot rocks on the territory of the Russian Federation for more than one year. The purpose of the work is to create, on the basis of domestic, high technologies, technical means for deep penetration into the bowels of the earth's crust. Currently, several variants of drilling tools (BS) have been developed, which have no analogues in world practice.

The operation of the first version of the BS is linked to the current conventional well drilling technology. Hard rock drilling speed (average density 2500-3300 kg/m3) up to 30 m/h, hole diameter 200-500 mm. The second variant of the BS performs drilling of wells in an autonomous and automatic mode. The launch is carried out from a special launch and acceptance platform, from which its movement is controlled. One thousand meters of BS in hard rocks will be able to pass within a few hours. Well diameter from 500 to 1000 mm. Reusable BS variants have great cost-effectiveness and huge potential value. The introduction of BS into production will open a new stage in the construction of wells and provide access to inexhaustible sources of thermal energy of the Earth.

For the needs of heat supply, the required depth of wells throughout the country lies in the range of up to 3-4.5 thousand meters and does not exceed 5-6 thousand meters. The temperature of the heat carrier for housing and communal heat supply does not go beyond 150 °C. For industrial facilities, the temperature, as a rule, does not exceed 180-200 °C.

The purpose of creating the GCC is to provide constant, affordable, cheap heat to remote, hard-to-reach and undeveloped regions of the Russian Federation. The duration of operation of the GCS is 25-30 years or more. The payback period of the stations (taking into account the latest drilling technologies) is 3-4 years.

The creation in the Russian Federation in the coming years of appropriate capacities for the use of geothermal energy for non-electric needs will make it possible to replace about 600 million tons of fuel equivalent. Savings can be up to 2 trillion rubles.

Until 2030, it becomes possible to create energy capacities to replace fire energy by up to 30%, and until 2040 to almost completely eliminate organic raw materials as fuel from the energy balance of the Russian Federation.

Literature

1. Goncharov S.A. Thermodynamics. Moscow: MGTUim. N.E. Bauman, 2002. 440 p.

2. Dyadkin Yu.D. etc. Geothermal thermal physics. St. Petersburg: Nauka, 1993. 255 p.

3. Mineral resource base of the fuel and energy complex of Russia. Status and prognosis / V.K. Branchhugov, E.A. Gavrilov, V.S. Litvinenko and others. Ed. V.Z. Garipova, E.A. Kozlovsky. M. 2004. 548 p.

4. Novikov G. P. et al. Drilling wells for thermal waters. M.: Nedra, 1986. 229 p.

The warmth of the earth. Possible sources of internal heat

Geothermy- science that studies the thermal field of the Earth. The average surface temperature of the Earth has a general tendency to decrease. Three billion years ago, the average temperature on the Earth's surface was 71 o, now it is 17 o. Sources of heat (thermal ) Earth's fields are internal and external processes. The heat of the Earth is caused by solar radiation and originates in the bowels of the planet. The values ​​of heat influx from both sources are quantitatively extremely different and their roles in the life of the planet are different. Solar heating of the Earth is 99.5% of the total amount of heat received by its surface, and internal heating accounts for 0.5%. In addition, the influx of internal heat is very unevenly distributed on the Earth and is concentrated mainly in places of manifestation of volcanism.

External source is solar radiation . Half of the solar energy is absorbed by the surface, vegetation and near-surface layer of the earth's crust. The other half is reflected into world space. Solar radiation maintains the temperature of the Earth's surface at an average of about 0 0 C. The Sun warms the near-surface layer of the Earth to an average depth of 8 - 30 m, with an average depth of 25 m, the effect of solar heat ceases and the temperature becomes constant (neutral layer). This depth is minimal in areas with a maritime climate and maximal in the Subpolar region. Below this boundary there is a belt of constant temperature corresponding to the average annual temperature of the area. So, for example, in Moscow on the territory of agricultural. academy. Timiryazev, at a depth of 20 m, the temperature has invariably remained equal to 4.2 ° C since 1882. In Paris, at a depth of 28 m, a thermometer has consistently shown 11.83 ° C for more than 100 years. The layer with a constant temperature is the deepest where perennial ( eternal Frost. Below the belt of constant temperature is the geothermal zone, which is characterized by heat generated by the Earth itself.

Internal sources are the bowels of the Earth. The Earth radiates more heat into space than it receives from the Sun. Internal sources include residual heat from the time when the planet was melted, the heat of thermonuclear reactions occurring in the bowels of the Earth, the heat of the gravitational compression of the Earth under the action of gravity, the heat of chemical reactions and crystallization processes, etc. (for example, tidal friction). The heat from the bowels comes mainly from the moving zones. The increase in temperature with depth is associated with the existence of internal heat sources - the decay of radioactive isotopes - U, Th, K, gravitational differentiation of matter, tidal friction, exothermic redox chemical reactions, metamorphism and phase transitions. The rate of temperature increase with depth is determined by a number of factors – thermal conductivity, rock permeability, proximity to volcanic chambers, etc.

Below the belt of constant temperatures there is an increase in temperature, on average 1 o per 33 m ( geothermal stage) or 3 o every 100 m ( geothermal gradient). These values ​​are indicators of the thermal field of the Earth. It is clear that these values ​​are average and different in magnitude in different areas or zones of the Earth. The geothermal step is different at different points on the Earth. For example, in Moscow - 38.4 m, in Leningrad 19.6, in Arkhangelsk - 10. So, when drilling a deep well on the Kola Peninsula at a depth of 12 km, a temperature of 150 ° was assumed, in reality it turned out to be about 220 degrees. When drilling wells in the northern Caspian at a depth of 3000 m, the temperature was assumed to be 150 degrees, but it turned out to be 108 degrees.

It should be noted that the climatic features of the area and the average annual temperature do not affect the change in the value of the geothermal step, the reasons lie in the following:

1) in the different thermal conductivity of the rocks that make up a particular area. Under the measure of thermal conductivity is understood the amount of heat in calories transferred in 1 second. Through a section of 1 cm 2 with a temperature gradient of 1 o C;

2) in the radioactivity of rocks, the greater the thermal conductivity and radioactivity, the lower the geothermal step;

3) in different conditions of occurrence of rocks and the age of their occurrence; observations have shown that the temperature rises faster in the layers collected in folds, they often have violations (cracks), through which the access of heat from the depths is facilitated;

4) the nature of groundwater: hot groundwater flows warm rocks, cold ones cool;

5) remoteness from the ocean: near the ocean due to the cooling of rocks by a mass of water, the geothermal step is larger, and at the contact it is smaller.

Knowing the specific value of the geothermal step is of great practical importance.

1. This is important when designing mines. In some cases, it will be necessary to take measures to artificially lower the temperature in deep workings (temperature - 50 ° C is the limit for a person in dry air and 40 ° C in wet air); in others, it will be possible to work at great depths.

2. The assessment of temperature conditions during tunneling in mountainous areas is of great importance.

3. The study of the geothermal conditions of the Earth's interior makes it possible to use steam and hot springs emerging on the Earth's surface. Underground heat is used, for example, in Italy, Iceland; in Russia, an experimental industrial power plant was built on natural heat in Kamchatka.

Using data on the size of the geothermal step, one can make some assumptions about the temperature conditions of the deep zones of the Earth. If we take the average value of the geothermal step as 33 m and assume that the increase in temperature with depth occurs evenly, then at a depth of 100 km there will be a temperature of 3000 ° C. This temperature exceeds the melting points of all substances known on Earth, therefore, at this depth there should be molten masses . But due to the huge pressure of 31,000 atm. Superheated masses do not have the characteristics of liquids, but are endowed with the characteristics of a solid body.

With depth, the geothermal step must apparently increase significantly. If we assume that the step does not change with depth, then the temperature in the center of the Earth should be about 200,000 degrees, and according to calculations, it cannot exceed 5000 - 10,000 degrees.

This energy belongs to alternative sources. Nowadays, more and more often they mention the possibilities of obtaining resources that the planet gives us. We can say that we live in an era of fashion for renewable energy. A lot of technical solutions, plans, theories in this area are being created.

It is deep in the bowels of the earth and has the properties of renewal, in other words it is endless. Classical resources, according to scientists, are beginning to run out, oil, coal, gas will run out.

Nesjavellir Geothermal Power Plant, Iceland

Therefore, one can gradually prepare to adopt new alternative methods of energy production. Under the earth's crust is a powerful core. Its temperature ranges from 3000 to 6000 degrees. The movement of lithospheric plates demonstrates its tremendous power. It manifests itself in the form of volcanic sloshing of magma. In the depths, radioactive decay occurs, sometimes prompting such natural disasters.

Usually magma heats the surface without going beyond it. This is how geysers or warm pools of water are obtained. In this way, physical processes can be used for the right purposes for humanity.

Types of geothermal energy sources

It is usually divided into two types: hydrothermal and petrothermal energy. The first is formed due to warm sources, and the second type is the temperature difference on the surface and in the depths of the earth. To put it in your own words, a hydrothermal spring is made up of steam and hot water, while a petrothermal spring is hidden deep underground.

Map of the development potential of geothermal energy in the world

For petrothermal energy, it is necessary to drill two wells, fill one with water, after which a soaring process will occur, which will come to the surface. There are three classes of geothermal areas:

• Geothermal - located near the continental plates. Temperature gradient over 80C/km. As an example, the Italian commune of Larderello. There is a power plant
• Semi-thermal - temperature 40 - 80 C / km. These are natural aquifers, consisting of crushed rocks. In some places in France, buildings are heated in this way.
• Normal - gradient less than 40 C/km. Representation of such areas is most common

They are an excellent source for consumption. They are in the rock, at a certain depth. Let's take a closer look at the classification:

• Epithermal - temperature from 50 to 90 s
• Mesothermal - 100 - 120 s
• Hypothermal - more than 200 s

These species are composed of different chemical composition. Depending on it, water can be used for various purposes. For example, in the production of electricity, heat supply (thermal routes), raw materials base.

Video: Geothermal Energy

Heat supply process

The water temperature is 50 -60 degrees, which is optimal for heating and hot supply of a residential area. The need for heating systems depends on the geographical location and climatic conditions. And people constantly need the needs of hot water supply. For this process, GTS (geothermal thermal stations) are being built.

If for the classical production of thermal energy a boiler house is used that consumes solid or gas fuel, then a geyser source is used in this production. The technical process is very simple, the same communications, thermal routes and equipment. It is enough to drill a well, clean it of gases, then send it to the boiler room with pumps, where the temperature schedule will be maintained, and then it will enter the heating main.

The main difference is that there is no need to use a fuel boiler. This significantly reduces the cost of thermal energy. In winter, subscribers receive heat and hot water supply, and in summer only hot water supply.

Power generation

Hot springs, geysers are the main components in the production of electricity. For this, several schemes are used, special power plants are being built. GTS device:

• DHW tank
• Pump
• Gas separator
• Steam separator
• generating turbine
• Capacitor
• booster pump
• Tank - cooler

As you can see, the main element of the circuit is a steam converter. This makes it possible to obtain purified steam, since it contains acids that destroy turbine equipment. It is possible to use a mixed scheme in the technological cycle, that is, water and steam are involved in the process. The liquid goes through the entire stage of purification from gases, as well as steam.

Circuit with binary source

The working component is a liquid with a low boiling point. Thermal water is also involved in the production of electricity and serves as a secondary raw material.

With its help, low-boiling source steam is formed. GTS with such a cycle of work can be fully automated and do not require the presence of maintenance personnel. More powerful stations use a two-circuit scheme. This type of power plant allows reaching a capacity of 10 MW. Double circuit structure:

• steam generator
• Turbine
• Capacitor
• Ejector
• Feed pump
• Economizer
• Evaporator

Practical use

Huge reserves of sources are many times greater than the annual energy consumption. But only a small fraction is used by mankind. The construction of the stations dates back to 1916. In Italy, the first GeoTPP with a capacity of 7.5 MW was created. The industry is actively developing in such countries as: USA, Iceland, Japan, Philippines, Italy.

Active exploration of potential sites and more convenient methods of extraction are underway. The production capacity is growing from year to year. If we take into account the economic indicator, then the cost of such an industry is equal to coal-fired thermal power plants. Iceland almost completely covers the communal and housing stock with a GT source. 80% of homes use hot water from wells for heating. Experts from the USA claim that, with proper development, GeoTPPs can produce 30 times more than annual consumption. If we talk about the potential, then 39 countries of the world will be able to fully provide themselves with electricity if they use the bowels of the earth to 100 percent.