Geothermal power plant statistics. Geothermal power plants are an excellent alternative to traditional methods of generating energy. Ways to use geothermal energy
The definition of geothermal energy lies in its very name - it is the energy of the heat of the earth's interior. The magma layer located under the earth's crust is a fiery liquid, most often silicate melt. It is estimated that the energy potential of heat at a depth of 10 thousand meters is 50 thousand times higher than the energy of the world's reserves of natural gas and oil. The magma that comes out to the surface of the earth is called lava. The greatest " throughput"The earth in a lava eruption is observed at the boundaries of tectonic plates and where the earth's crust is thin enough. When lava comes in contact with the planet's water resources, a sharp heating of the water begins, which leads to geyser eruptions, the formation of hot lakes and underwater currents. , arise natural phenomena, the properties of which can be used as an almost inexhaustible source of energy. The sources of geothermal energy are practically inexhaustible. True, they are not widespread everywhere, although they are found in more than 60 countries around the world. The largest number of active terrestrial volcanoes are located in the Pacific Volcanic Ring of Fire (328 out of 540 known). The geothermal gradient in the well, which is used to reach underground energy, rises by 1 ° C every 36 meters. The heat generated in this way enters the surface in the form of hot steam or water, which can be used directly to heat buildings or indirectly to generate electricity. In practice, geothermal sources in different regions of the planet differ significantly from each other, which is why they have to be classified into dozens different characteristics, such as average temperature, salinity, gas composition, acidity, etc. In terms of practical application for generating electrical energy, the main classification of geothermal sources can be considered a division into three main types:- Direct - dry steam is used;
- Indirect - water vapor is used;
- Mixed (binary cycle).
The use of geothermal sources in the world
The first geothermal power plant in the USSR was built in Kamchatka - this is the Pauzhetskaya Geothermal Power Plant, which began its work in 1967. The original capacity of the station was 5 MW; subsequently, it was increased to 11 MW. The potential of hydrothermal deposits in Kamchatka is enormous. The heat reserves of geothermal waters are estimated here at 5000 MW. Full use of geothermal heat could solve the energy problem of the Kamchatka region, make it independent of imported fuel. The most studied and most promising is the Mutnovskoye geothermal field, located 90 kilometers south of the city of Petropavlovsk-Kamchatsky. Back in 1986, an assessment carried out by the Institute of Volcanology of the Russian Academy of Sciences showed that the predicted resources of the field are 312 MW in terms of heat removal, and 450 MW in terms of volumetric method. The experimental-industrial Verkhne-Mutnovskaya Geothermal Power Plant with a capacity of 12 (3x4) MW has been operating since 1999. Installed capacity for 2004 - 12 MW. Phase I of the Mutnovskaya Geothermal Power Plant with a capacity of 50 (2x25) MW was connected to the grid on April 10, 2003; the installed capacity for 2007 is 50 MW, the planned capacity of the station is 80 MW. The operating geothermal power plants provide up to 30% of the energy consumption of the central Kamchatka power center. It is pleasant to note that the thermo-mechanical equipment of the Geothermal power plant at the Mutnovskoye field has been developed, created and supplied domestic factories: turbines belong to JSC "KTZ", separators - JSC "PMZ", power fittings - JSC "ChZEM", etc. The Kuril Islands are rich in heat reserves. In particular, wells have already been drilled and a geothermal power plant is under construction on the Iturup island, at the Okeanskoye geothermal field. There are reserves of geothermal heat on the southern island of Kunashir, and they are already being used to generate electricity and heat the city of Yuzhno Kurilsk. On the island of Paramushir, which has geothermal water reserves with temperatures ranging from 70 to 95 ° C, a GeoTS with a capacity of 20 MW is being built. Chukotka has significant reserves of geothermal heat (on the border with the Kamchatka region). They are partially open and used to heat nearby settlements. In Russia, the use of geothermal energy, except for Kamchatka, the Kuriles, Primorye, the Baikal region and the West Siberian region, is possible in the North Caucasus. Geothermal deposits with temperatures ranging from 70 to 180 ° C, located at a depth of 300 to 5000 meters, have been studied here. In Dagestan in 2000 alone, more than 6 million cubic meters of geothermal water were extracted. In total, in the North Caucasus, about half a million people are provided with geothermal water supply. Today, the world leaders in geothermal power generation are the United States, the Philippines, Mexico, Indonesia, Italy, Japan, New Zealand and Iceland. The latter state is a particularly striking example of the use of geothermal energy. The island of Iceland appeared on the ocean surface as a result of volcanic eruptions 17 million years ago, and now its inhabitants enjoy their privileged position - about 90% of Icelandic houses are heated by underground energy. With regard to power generation, there are five Geothermal Power Plants with a total capacity of 420 MW, using hot steam from a depth of 600 to 1000 meters. Thus, geothermal sources generate 26.5% of all electricity in Iceland.Top 15 countries using geothermal energy (data for 2007)
Energy is low potential, but promising
Geothermal springs can be divided into low, medium and high temperature. The former (with temperatures up to 150 ° C) are used, for the most part, for heat supply with hot water - it is supplied through pipes to buildings (residential and industrial), swimming pools, greenhouses, etc. The latter (with temperatures above 150 ° C), containing dry or wet steam, are suitable for driving the turbines of geothermal power plants (Geothermal power plants). A significant disadvantage of "hot" geothermal springs is their "selective" location in places of tectonic instability, as mentioned above. If we take Russia, then the reserves of high-potential geothermal energy can be used only in Kamchatka, the Kuriles and in the region of the Caucasian mineral waters. But the terrestrial "boiler room" has not only high-potential, but also low-potential energy, the source of which is the soil of the surface layers of the earth (up to 400 m deep) or underground waters with a relatively low temperature. Low-grade heat can be used with heat pumps. The thermal regime of the soil of the earth surface layers is created under the influence of radiogenic heat coming from the bowels of the earth, as well as the solar radiation falling on the surface. The intensity of the incident solar radiation can fluctuate depending on the specific soil and climatic conditions in the range from several tens of centimeters to one and a half meters. Low-grade heat can be effectively used for heating buildings, hot water supply, heating various structures (for example, fields of open stadiums). In the last decade, there has been a significant increase in the number of systems that use underground resources to supply buildings with heat and cold. Most of these systems are located in the United States. They are also available in Austria, Germany, Sweden, Switzerland, Canada. There are only a few such systems in our country. In European countries, heat pumps mainly heat the premises. In the USA, where air heating systems are combined with ventilation, the air is not only heated, but also cooled. If we talk about Russia, an example of using a low-potential source of thermal energy is in Moscow, in the Nikulino-2 microdistrict. A heat pump system was built here to supply hot water to a multi-storey residential building. This project was implemented in 1998-2002 by the Ministry of Defense of the Russian Federation jointly with the government of Moscow, the Ministry of Industry and Science of Russia, NP "AVOK" and OJSC "Insolar-Invest" within the framework of the "Long-term energy saving program in St. Moscow. "There are two types of systems for the use of low-potential thermal energy of the earth: open systems and closed systems. The first use groundwater supplied directly to heat pumps, the second - the ground mass. For open systems, paired wells are characteristic, with which groundwater is not only extracted but then they return back to the aquifers.Open systems provide a large amount of thermal energy at a relatively low cost.However, the soil must be permeable to water and the groundwater must have a usable chemical composition to avoid corrosion and deposits on the pipe walls. The world's largest groundwater geothermal heat pump system, located in Louisville, USA, supplies heat and cold to a hotel and office complex with a capacity of approximately 10 MW and is divided into vertical and horizontal closed systems. Vertical ground heat exchangers use low-grade thermal energy the soil massif below the so-called "neutral zone" (10-20 meters above ground level). Such systems do not require large areas, and also do not depend on the intensity of solar radiation falling on the surface. Almost all types of geological media are suitable for them, except for soils with low thermal conductivity, for example, dry sand or gravel. In vertical ground heat exchangers, the coolant circulates through pipes (most often polypropylene or polyethylene) laid in vertical wells with a depth of 50 to 200 meters. Two types of vertical ground heat exchangers are commonly used: U-shaped and coaxial. The first one is two parallel pipes connected at the bottom. One well contains one or two pairs of such pipes. The advantage of the U-type is the relatively low manufacturing cost. The second type of heat exchanger (also called concentric) consists of two pipes of different diameters, one of which is placed inside the other. Systems with vertical ground heat exchangers are suitable for supplying buildings with both heat and cold. One heat exchanger is enough for a small building, but for large buildings, several wells with vertical heat exchangers may be needed. As an example of the latter is the heating and cooling system of the American college "Richard Stockton College", which uses a record number of wells - 400 (130 meters deep). In Europe, the largest number of wells (154 wells 70 meters deep) have been drilled for the heating and cooling system of the headquarters of the German Air Traffic Control Service. Horizontal ground heat exchangers are usually created not far from the building, at a shallow depth, but always below the freezing level of the ground in winter. In Europe, such heat exchangers are tightly connected (in series or parallel) pipes. To save space, special types of heat exchangers have been created, for example, in the form of a spiral. It is promising to use water from tunnels and mines as a source of low-grade thermal energy, since the water temperature in them has a constant temperature all year round and is easily accessible. The use of underground heat, both high-grade and low-grade, is considered extremely promising. This is especially true for providing buildings with warm and cooled air using low-grade heat. According to forecasts of the World Energy Committee (MIREC), by 2020 the developed countries of the world will become quite active in supplying heat with heat pump systems. And here not only "hot" earth bowels are suitable, but also the air and water of the seas and oceans. For example, in Sweden, where a station on six barges with a capacity of 320 MW is located near Stockholm, they use the water of the Baltic Sea with a temperature of +4 ° C. IN Russian Federation huge reserves of natural gas, oil, coal and timber allow (for the time being) not to think too much about alternative energy sources. However, work on the development of geothermal sources has been carried out on its territory for several decades, which indicates an understanding of the importance of the issue. After all, we are talking about inexhaustible sources of heat and electricity, which, sooner or later, will become important, and, possibly, the main suppliers of energy for all mankind, and not just for individual countries.Geothermal power plants in Russia are a promising renewable source. Russia has rich geothermal resources with high and low temperatures and is making good steps in this direction. An environmental protection concept can help demonstrate the benefits of renewable alternative energy sources.
In Russia, geothermal research was carried out in 53 scientific centers and higher educational institutions located in different cities and in different departments: the Academy of Sciences, the Ministries of Education, Natural Resources, Fuel and Energy. Such work is carried out in some regional scientific centers such as Moscow, St. Petersburg, Arkhangelsk, Makhachkala, Gelendzhik, Volga region (Yaroslavl, Kazan, Samara), Ural (Ufa, Yekaterinburg, Perm, Orenburg), Siberia (Novosibirsk, Tyumen, Tomsk, Irkutsk, Yakutsk), the Far East (Khabarovsk, Vladivostok, Yuzhno-Sakhalinsk, Petropavlovsk-on-Kamchatka).
In these centers, theoretical, applied, regional research is carried out, and special tools are created.
Use of geothermal energy
Geothermal power plants in Russia are mainly used for heat supply and heating of several cities and towns in the North Caucasus and Kamchatka with a total population of 500 thousand people. In addition, in some regions of the country, deep heat is used for greenhouses with a total area of \u200b\u200b465 thousand m 2. The most active hydrothermal resources are used in the Krasnodar Territory, Dagestan and Kamchatka. About half of the extracted resources are used for heating housing and industrial premises, a third for heating greenhouses, and only about 13% for industrial processes.
In addition, the thermal waters are used in about 150 sanatoriums and 40 bottling plants. The amount of electricity generated by geothermal power plants in Russia is increasing compared to the world, but remains extremely insignificant.
The share is only 0.01 percent of the country's total electricity generation.
The most promising direction for using low-temperature geothermal resources is the use of heat pumps. This method is optimal for many regions of Russia - in the European part of Russia and in the Urals. So far, the first steps are being taken in this direction.
Electricity is generated at some power plants (GeoPP) only in Kamchatka and the Kuril Islands. Currently, three stations are operating in Kamchatka:
Pauzhetskaya GeoPP (12 MW), Verkhne-Mutnovskaya (12 MW) and Mutnovskaya GeoPP (50 MW).
Pauzhetskaya GeoPP inside
Two small GeoPPs are in operation on the Kunashir Islands - Mendeleevskaya GeoTES, Iturup - Okeanskaya with an installed capacity of 7.4 MW and 2.6 MW, respectively.
Geothermal power plants in Russia are in the last places in the world in terms of their volume.In Icelandaccounts for more than 25% of the electricity produced by this method.
Mendeleevskaya Geothermal Power Plant on Kunashir
Iturup - "Oceanic"
Russia has significant geothermal resources and the available potential is much greater than the current situation.
This resource is far from being adequately developed in the country. In the former Soviet Union, exploration for minerals, oil and gas was well supported. However, such an extensive activity is not directed towards the study of geothermal reservoirs, even as a consequence of the approach: geothermal waters were not considered an energy resource. Still, the results of drilling thousands of “dry wells” (colloquially in the oil industry) bring secondary benefits to geothermal exploration. These abandoned wells that were cheaper during the research of the oil industry to give away for new purposes.
Benefits and problems of using geothermal resources
The environmental benefits of using renewable energy sources such as geothermal are recognized. However, there are serious obstacles to the development of renewable resources that hinder development. Detailed geological surveys and expensive geothermal drilling represent large financial costs associated with significant geological and technical risks. 
The use of renewable energy sources, including geothermal resources, has advantages as well.
- First, the use of local energy resources can reduce dependence on imports or the need to build new generating capacity for heating in industrial or residential hot water areas.
- Second, replacing traditional fuels with clean energy results in significant environmental and public health improvements and associated savings.
- Third, a measure of energy savings is related to efficiency. District heating systems are common in urban centers of Russia and need modernization and transition to renewable energy sources with their own advantages. This is especially important from an economic point of view, outdated district heating systems are not economical and the engineering lifetime has already expired.
Geothermal power plants in Russia are "cleaner" compared to the fossil fuels used. The International Convention on Climate Change and European Community programs provide for the promotion of renewable energy sources. However, there are no specific legal requirements for exploration and extraction of geothermal waters in all countries. This is partly due to the fact that waters are regulated in accordance with the laws of water resources, minerals in accordance with energy laws.
Geothermal energy does not belong to certain areas of legislation and it is difficult to solve various methods of exploitation and use of geothermal power.
Geothermal energy and sustainable development
Industrial development over the past two centuries has brought many innovations to human civilization and brought the exploitation of natural resources at an alarming rate. Since the seventies of the 20th century, serious warnings about “limits to growth” have spread all over the world with great effect: resource of exploitation, arms race, wasteful consumption squandered these resources at an accelerated pace, along with exponential growth of the world's population. All this madness requires more energy.
The most wasteful and hopeless is human irresponsibility due to the habit of using up the finite and rapidly depleting energy resources of coal, oil and gas. This irresponsible activity is carried out by chemical industry for the production of plastics, synthetic fibers, building materials, paints, varnishes, pharmaceutical and cosmetic products, pesticides and many other organic chemistry products.
But the most catastrophic effect of the use of fossil fuels is the balance of the biosphere and climate to such an extent that it will irreversibly affect our life choices: the growth of deserts, acid rain spoiling fertile lands, poisoning of rivers, lakes and groundwater, spoilage drinking water for the world's growing population - and worst of all - more frequent weather disasters, retracting glaciers, destroying ski resorts, melting glaciers, landslides, more severe storms, flooding of densely populated coastal areas and islands, thereby endangering people and rare species flora and fauna as a result of migration.
The loss of fertile land and cultural heritage is due to the extraction of inexorably growing fossil fuels, emissions into the atmosphere, causing global warming.
The path to clean, sustainable energy that conserves resources and the attraction of the biosphere and climate to the natural balance is associated with the use in the form of geothermal power plants in Russia.
Scientists understand the need to reduce the burning of fossil fuels beyond the Kyoto targets in order to slow the global warming of the Earth's atmosphere.
Geothermal TPPs in the fields of steam-water mixture or geothermal brines with condensation turbines and one or multiple expansion of the geothermal fluid.
If at the deposits of the steam-water mixture the temperature of the separated water is high enough (above 100 ° C), then it is possible by expansion [by releasing the pressure in the expander 9 (Fig.) To obtain additional steam, which is directed to the intermediate inlet of the turbine.
This allows you to get additional work and, thereby, increase the efficiency of the power plant. Theoretically, there can be several such cascades. In practice, however, the possibility of using such schemes is limited by salt deposition in equipment elements as a result of an increase in salt concentration above the limiting solubility. In the deposits of the steam-water mixture, deposits of silicic acid are formed first of all, the solubility of which rapidly decreases with decreasing temperature. At the deposits of geothermal brines extracted from carbonate reservoirs (North Caucasus), when brines expand, dissolved CO2 is released, which leads to a violation of carbon dioxide equilibrium and the formation of deposits of calcite, magnesite, etc. Therefore, the use of schemes with expanders is possible only in the absence of massive scale deposits or when using regular equipment cleaning.
Expanders are relatively cheap volumetric devices and, therefore, their use practically does not increase the capital investment, which remains at the level of 1000 USD / kW.
Ri from . 3.Schema Geo TPP with condensation turbine and expansion
geo fluid temperature:
1 - lifting well; 2 - separator; 3 - condensing turbine; 4 - capacitor; 5 - cooling tower; 6 - circulation pump; 7 - condensate pump; 8 - injection well; 9 - expander.
Geothermal power plants using low-boiling pure or mixed working fluids.
In order to avoid scaling arising from the evaporation of geothermal brines in schemes with expanders, a scheme using low-boiling working fluids is used.
Geothermal brine from a lifting well 1
enters the heat exchanger-steam generator 2
(which is usually performed in the form of two shell-and-tube devices - an evaporator and a heater (economizer)). After cooling to the limiting temperature, determined by the condition of the absence of salt deposits, the brine returns back to the reservoir through the injection well 3
... Due to the high cost of wells, submersible pumps are sometimes used to increase the flow rate of geothermal brine, placed at a depth of 200 m in a lifting well, and for re-injection, an injection pump is almost always used in front of a reinjection well. 3
... The power consumption for driving these pumps sometimes reaches 20% of the power generation.
Ri from . 4 . Scheme of a Geo TPP using low boiling and working bodies:
1 — by the height of the wells; 2 - heat exchange - steam generator ato r; 3 - injection I from wells; 4 - tour bin a; 5 - to about nde nsato r; 6 — circulating uswasps
Refrigerants (hydrocarbons: propane, butane, freons) are used as working fluids for such geothermal power plants, recently the possibility of using an ammonia-water mixture is being considered. The liquid working fluid is heated and evaporated in the steam generator 2 and is fed to the turbine inlet 4 ... The expansion of the vapor of low-boiling working bodies in the turbine occurs (in contrast to water vapor) in the region of dry vapor, which is associated with the anomalous form of the right branch of their saturation curves in T,s-diagram — entropy decreases with decreasing temperature, so dry steam comes out of the turbine. If its temperature is significantly higher than the condensing temperature, usually determined by the air temperature, it is advisable to return the excess heat to the cycle, for which a recuperative heat exchanger not shown in the diagram is used, installed before the condenser. 5 which is usually air-cooled due to the lack of cooling water. Condensed working fluid with a circulation pump 6 supplied to the input of the steam generator (if there is a recuperator, through it).The world's first geothermal power plant according to this scheme with Freon-22 as a working fluid was manufactured in 1956 and tested at the Paratunskoye field of thermal waters in Kamchatka. Equipment for such geothermal power plants with different working bodies was manufactured by a number of companies in the USA, Japan, Italy, Austria. At present, the industrial production of power modules with a capacity of 0.5 ... 3 MW with low-boiling working bodies is carried out by the Ormat company (Israel). The total capacity of geothermal power plants built in many countries with these energy modules exceeds 350 MW. In our country, at the Kirov plant, a 1.5 MW power module was designed using ozone-safe Freon-42b. At present, work on the creation of a special turbine is being carried out at JSC "Science".
IN last years special attention is paid to the use of ammonia-water mixture as a working fluid. This interest is due to the change in temperature during the vaporization of the mixture - first, at a lower temperature, ammonia mainly boils away, and as its concentration decreases, the temperature of the boiling mixture increases. As a result, it is possible to approximate the cooling curves of the geothermal brine and the heating and vaporization of the ammonia-water mixture in I,t-diagram, which leads to a decrease in irreversible losses of exergy during heat exchange and an increase in the efficiency of the GeoTPP cycle. In addition, by changing the concentration of ammonia in the mixture, one and the same turbine can be effectively used in geothermal fields with brine temperatures of 80 ... 200 ° C.
E n er homo d u l the "ORMAT" firms are supplied at an average price of 100 0 USD. for 1 k W.
Combined cycle geothermal power plants with a steam turbine in the upper cycle and a low-boiling working fluid in the lower cycle.
D la more full use of the geothermal steam-water mixture and the more efficient use of the combined heat circuit.
From the lifting well 1 the steam-water mixture is fed to the separator 2 where the steam is directed to the back pressure steam turbine 3 , after leaving the turbine, steam enters the condenser 4 , which is a steam generator of a low-boiling working fluid. The resulting condensate is used at the station. The separated hot geothermal brine is fed to the superheater of the low-boiling working fluid 5 , after which it returns to the reservoir through the injection well 10 ... Superheated steam of low-boiling RT is fed to the inlet of a binary turbine 6 , after expansion in which it goes to the recuperator 7 where it cools and goes to the air condenser 8 ... Condensed low boiling point RT by feed pump 9 supplied for preheating to the recuperator 7 and then into the steam generator 4 ... This scheme makes it possible to use the heat of the separated brine to overheat the low-boiling RT, which leads to an increase in the efficiency of the GeoTPP. The use of such a scheme is especially effective at low air temperatures, since due to the low freezing temperatures of low-boiling RTs (below -50 ° C), condensation can be carried out at negative temperatures. For the conditions of the Mutnovsky steam-water mixture field (average annual air temperature - 5 ° C), electricity generation at the combined geothermal power plant increases by 20% compared to the traditional condensation cycle. The corresponding patent was obtained jointly by JSC Nauka and JSC ENIN im. G.M. Krzhizhanovsky ".
tocondenser; 5 — superheater; 6 - binary I turbine; 7 - recuperator; 8 - air condenser; 9 - nutritiousth pump; 1 0 - injection well.
Combined cycle geothermal power plant equipment is manufactured by the Israeli company Ormat, it is installed at a number of geothermal power plants in the Philippines and Indonesia. In Russia, according to this scheme, it is planned to build the 4th block of the Verkhne-Mutnovskaya Geothermal Power Plant with a total capacity of 6 MW.
Vasiliev V.A., Tarnizhevsky B.V., JSC "ENIN"
The technology for converting geothermal energy into electricity depends mainly on the parameters of the heat carrier. High potential geothermal water supplying geothermal power plant (GeoPP) high pressure steam, allow directing such a coolant directly to the turbine blades. In this case, the generating part of the GeoTPP does not fundamentally differ from the traditional thermal power plant using hydrocarbon fuel.
Mechanical impurities and gases contained in geothermal water or steam are cleaned using separators and filters. With a significant amount of impurities, which are often aggressive, a two-circuit system with a heat exchanger is used. The secondary circuit contains water that has been chemically treated and dearized. An example of such a GeoPP is Mutnovskaya geothermal power plantlocated 140 km from the city of Petropavlovsk-Kamchatsky at the foot of the active volcano Mutnovsky. Prior to the start of construction of the Mutnovskaya GeoPP, in the same place, the Verkhne-Mutnovskaya station with a capacity of 12 MW was previously commissioned. In addition, in 1967 in the south of the Kamchatka region, the Pauzhetskaya GeoPP with a capacity of 11 MW was built, which continues to operate today. tadalafil 20 mg
The first block of the Mutnovskaya GeoPP with a capacity of 25 MW was commissioned in 2001. A year later, with the commissioning of the second power unit, the plant's capacity increased to 50 MW. The second stage of the Mutnovskaya GeoPP was commissioned in 2007-2009 and is increasing the plant's capacity by 100 MW. The third stage with a capacity of over 100 MW is planned for 2012. Mutnovskaya GeoPP for a number of years has been demonstrating stable operation and producing cheap electricity, the cost of which is about 1.5 cents / kWh. In general, Mutnovskaya GeoPP is in many ways superior in its technical specifications foreign analogues:
- ecological purity, which is achieved by eliminating direct contact of the geothermal coolant with the environment, followed by its injection back into the earth's strata;
- the problem of protecting the station equipment from corrosion and salt deposits has been largely solved by using a special technology of film-forming amine additives;
- block-modular principle of equipment supply, which made it possible to significantly reduce the construction time of the station.
Already today, geothermal energy provides more than 25% of Kamchatka's electricity demand, which makes it possible to weaken the peninsula's dependence on the supply of expensive fuel.
It should be noted that geothermal power plants with a high-grade heat carrier can only be constructed near the corresponding deposits of geothermal waters. There are not many such deposits, respectively, and power plants of the considered type are quite unique objects. Geothermal waters with lower in-situ temperatures are much more accessible and widespread. As noted above, Western Siberia has huge reserves of geothermal waters with temperatures up to 100 ° C.
Technologies for generating electricity from low-grade thermal energy of geothermal waters are based on two principles of energy conversion: the use of substances with low boiling points and hydro-steam turbines of the Segner wheel type.
The idea of \u200b\u200bgenerating electricity in turbine generators using substances with low boiling points belongs to Soviet scientists, who in 1965-1967. created the world's first geothermal binary power plant in Kamchatka - Paratunskaya GeoPP... Freon, converted into steam by the warmth of hot water, was sent to a turbine generator that generates electrical energy. Today this technology is actively used. About a thousand power units with a capacity of several kW to 130 MW have been built in dozens of countries around the world.
Hydro-steam turbine plants (HPT) use a direct supply of hot water to the turbine nozzles without first separating it into steam and water in separators. A hydro-steam turbine operates on a stream that boils during adiabatic expansion. The main work in the process of converting the thermal energy of geothermal waters into the kinetic energy of the working stream and the mechanical turbine is carried out by the liquid phase, which fundamentally distinguishes a hydro-steam turbine from a steam turbine. The GPT uses Laval nozzles with steam generating grids that create a finely dispersed steam-water flow on the turbine blades.
Such power plants have an efficiency of up to 25-30% at an output shaft speed of up to several thousand revolutions per minute. At St. Petersburg Technical University, a simple and universal model of a jet turbine has been proposed in the form Segner's wheels (fig. below).
In the pressure head of the turbine, the pressure of hot water increases, and in the Laval nozzle, the acceleration of hot water in the converging part of the nozzle and expansion of the steam-water mixture in the expanding part of the nozzle. Thus, in Segner's wheel there is an acceleration of the flow of hot water, its evaporation and expansion of the steam-water mixture without changing the direction of flow. Such turbines have a number of fundamental advantages:
- the minimum number of moving parts, which ensures ease of maintenance;
- high efficiency of axisymmetric nozzles as a source of reactive force on the wheel;
- the absence of rotor blades, which reduces the problems of flow, and erosion during the passage of the steam-water mixture;
- fundamentally new possibilities of turbine power regulation.
Estimated cost of equipment for hydro-steam turbines with a capacity of 100-150 kW is 600-750 $ / kW. According to the equipment developers: ZAO NPVP "Turbokon", Kaluga and the Institute of Thermophysics SB RAS, Novosibirsk, hydro-steam turbines can effectively use geothermal water with a temperature of 80-150 ° С.
"Renewable Energy in Decentralized Power Supply"
Lukutin B.V., Surzhikova O.A., Shandarova E.B.
Geothermal power plants. More than 30 states have already adopted or are already considering standards according to which part of the electricity consumed by utilities should be taken from renewable sources. The lists of such sources, as a rule, include geothermal power plants (GeoPPs) that use hot groundwater or steam. Enterprises, as a rule, do not want to contact GeoPPs because of their high initial cost, which is due to the need to drill research wells at the design stage and create underground storage facilities for hot water located much closer to the surface than natural hot groundwater. But already built geothermal power plants do not require any fuel and almost do not pollute environment... The cost of these stations, calculated for a long period of operation, does not exceed the cost of coal-fired thermal power plants, the cheapest of the traditional ones. Currently, several types of GeoPPs have been developed, which have already been implemented and have been operating for a long time. The most common are the so-called direct action stations ( flash plants), but in the future, apparently, binary action stations ( binary plants), in which hot water from underground sources evaporates and condenses into water of a lower temperature. Some worry about the gradual depletion of sources due to the inevitable loss of water during its conversion to steam and subsequent cooling. However, this is hardly worth fearing, since water reserves will be continuously replenished - after all, it quickly seeps through the bowels. In a two-stage process, almost all of the water extracted from the bowels is returned to the reservoir. In the future, most likely, utilities will use hot water simply heated by hot rock, and individual consumers will take it from wells right in their yards. At a depth of 3 m, the temperature is 10–15 ° C all year round. Fluid-filled pipes laid at this depth can be connected to a heat pump in the house and provide cooling in summer and heating in winter. When you start building new housethink about it: installing a heat pump will certainly cost you more than installing a conventional heating system, but you won't have to think about fuel, apart from a tiny amount of electricity. In 4–5 years, all expenses will pay off and you will start saving on the envy of your neighbors.
Geothermal power plant of the future. Pressurized cold water is injected into dry fractures, where it causes hydraulic fracturing, seeps into fractures and heats up. Hot water is pumped through pipes to the GeoPP.
Geothermal power plants use the thermal energy of the bowels. As a rule, now in most cases a direct production cycle is used, but in the future, most likely, the binary one will prevail. High pressure steam drives turbines. The non-evaporated water is returned to the underground reservoir.
Building can be heated by directly pumping hot water or steam through the pipes of the heating system.
Residential buildings. The heat pump pumps fluid through pipes located shallow underground. The temperature at a depth of 3 m is maintained at 10–15 ° С all year round. In summer, the liquid will be colder than the environment surrounding the house, and heat will be removed, and in winter, on the contrary, a relatively warmer liquid will heat the room.
Direct production cycle. Superheated water from the bowels under the influence of natural high pressure enters the separator, where a lower pressure is maintained. Under the influence of the pressure drop, part of the liquid instantly turns into steam. The rest of the water enters the second tank with the same low pressure as in the first, where it also boils instantly.
Binary production cycle. Superheated water from the bowels enters the heat exchanger, where it heats a low-boiling liquid (for example, isobutane), which circulates in a closed loop of the pipeline. The result is high pressure steam.
Do you know that?..
- A LOT BUT NOT ENOUGH. Geothermal plants operate in 24 countries. Their total capacity reaches 8,900 MW, which is only 0.36% of the global capacity. The largest contribution is made by the USA - 2850 MW (of which 2490 MW - in California). Since 2000, geothermal power has tripled in France, Kenya and Russia.
- RELIABLE. The world's largest geothermal complex, the Geysers, is located 72 miles north of San Francisco. Since 1960, 21 stations with a total capacity of 750 MW have been operating here. In the city of Santa Rosa, wastewater is now pumped underground, replenishing natural water supplies.
- NOT ALL CLEAR. Some groundwater contains many dissolved gases, such as carbon dioxide and hydrogen sulfide, and metals such as zinc. These impurities destroy the plant's installations and apparatus. In stations with a binary production cycle, groundwater does not come into contact with machines. All impurities are discharged back to the underground reservoir.
Abbr. per. from English. N. D. Kozlovoy