Power Technology and Engineering
Vol. 43, No. 4, 2009
A METHOD OF INCREASING THE OPERATING EFFICIENCY OF GEOTHERMAL ELECTRIC POWER STATIONS A. S. Latkin,1 B. E. Parshin,2 T. P. Belova,1 O. L. Basmanov2 and M. L. Bezotechestvo2 Translated from Élektricheskie Stantsii, No. 6, pp. 42 – 48, 2009.
It is shown that the existing technological systems of geothermal power stations in Russia do not enable the thermal potential of underground hot water to be used efficiently due to the presence of mineral compounds in them. To increase the operating efficiency of these natural resources, a complex approach to them — both to the heat-transfer agents and to the raw sources of mineral compounds — is required. Keywords: complex utilization, steam-water mixture, geothermal heat-transfer gents, separation, mineral compounds, chemical components.
The history of the development of world geothermal power engineering began in 1904 when J. Conti, at a chemical enterprise in the town of Lardarello in Northwestern Italy, constructed an experimental 10 kW electric power generator, using natural steam pressure. The industrial utilization of geothermal resources began after the start-up in 1916 in Italy of a 7.5 MW geothermal electric power station with three turbines, each of 2.5 MW power [1 – 4]. At the present time the overall installed power of geothermal electric power stations in Italy amounts to 790 MW. After the long leadership of Italy in geothermal power engineering, in 1958 in New Zealand a geothermal electric power station began to operate, the power of which was subsequently increased from 147 MW to 190 MW. In 1960 in the USA a 12 MW geothermal electric power station came into operation in California, which made use of geysers. In 1967 geothermal electric power stations came into operation in Japan and the USSR, followed by Iceland, Mexico, Turkey and many other countries. At present, geothermal electric power stations operate in more than 20 countries, their installed power is constantly increasing and in 2004 amounted to 8758.9 MW [2 – 4]. A leader in utilizing geothermal energy is the USA with an installed geothermal power station power of 2395 MW, according to 2004 data. As part of the program for developing geothermal power, the USA in the next 10 – 15 years can expect to double the power of geothermal electric power stations every five years. The predictions for the construction of geothermal electric power stations over the whole world look extremely optimistic [1]. In recent years their power has in1 2
creased by more than 40% and has reached 11 400 MW. The leaders here are the countries of South-East Asia. In the Philippines, during the last five years, geothermal electric power stations with a power of 682 MW have been introduced (with an overall installed power of 1931 MW), while in Indonesia geothermal electric power stations with a power of 280 MW have been put into service (for an overall installed power of 807 MW). The specific costs of constructing a geothermal electric power station in the USA is 38% less, on average, than a nuclear power station, and 50% less compared with a coal-fired thermal power station. The cost of electric energy is 25 – 30% less than from traditional electric power stations [3]. It follows from experience in operating large geothermal electric power stations in the Philippines, New Zealand, Mexico and the USA that the cost of 1 kW × h of electric power often does not exceed 1 cent, and it is also necessary to bear in mind that the installed power utilization factor (IPUF) for a geothermal electric power station reaches values of 0.95 [4]. The characteristics of geothermal electric power stations appear to be completely achievable compared with those of electric power stations using other forms of renewable sources of electric power [5] (see the table). At the present time there are four geothermal electric power stations functioning in Russia (three are situated in Kamchatka and one in the Kurils), the overall power potential of steam-water therms of which is estimated to be 1.2 GW of operating electric power, but only 76.5 MW of installed power is being obtained for an annual production of electric power of about 420 ´ 106 kW × h according to 2004 data [4]: the Upper-Mutnov geothermal electric power station with an installed power of 12 MW and a production of
Scientific-Research Geotechnology Center, Far-Eastern Division of the Russian Academy of Sciences, Russia. “Geoterm” Joint Stock Company, Russia.
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52.9 ´ 106 kW × h per year, the Mutnov geomethermal electric power station with an installed of 50 MW and a production of 360.7 ´ 106 kW × h per year on the Mutnov deposit; the Pauzhetskii geothermal electric power station with an installed power of 14.5 MW and which produces 59.5 ´ 106 kW × h/year on the Pauzhetskii deposit alongside the Koshelev and Kambal’nii volcanos; the maritime geothermal electric power station with an installed power of 3.6 MW situated on Iturup Island (Kurils). Geothermal heat-transfer agents in the steam-water phase state as a rule are used in existing geothermal electric power stations at the present time. A qualitative separation of the phases is required for the effective utilization of their thermal potential, since only steam enters the turbine of the power station. When separating the steam-water mixture the overwhelming amount of chemical materials remain in the liquid, while the working steam contains practically no mineral components. Hence, the design of effective separation equipment for separating the steam-water mixture is a problem that is extremely important for geothermal power engineering, and enables one, on the one hand, to increase the operating reliability of the power station, and on the other, to obtain a productive mixture containing chemical compounds of some interest in ecological and chemical-engineering schemes. Practically all the mineral raw material (including the geothermal fluids) consist of viable components, for which it is mined, an inert part and accompanying components. For existing technological processes of the primary processing of the mineral raw material, the specific cost of the traditionally obtained conditioned product Str, ignoring the cost of the mining enrichment system, can be represented by the following expression [6]: Str = Spp + Seo + Scr + Srp + Scp + Sw ,
(1)
where Spp is the cost of preliminary processing (opening and constructing the mine etc.), Seo is the cost of extracting the ore, Scr is the cost of crushing and obtaining the concentrate, Srp is the cost of obtaining the raw product, Scp is the cost of obtaining the conditioned product, and Sw is the cost of storing and utilizing the waste products, while the cost of the conditioned product of geothermal heat-transfer agent Sg, ignoring the cost of constructing the industrial enterprise, can be represented by the expression
Sg = Sd + S *rp + S *cp + Srb – See ,
(2)
where Sd is the cost of drilling the technological bore hole, S *rp is the cost of obtaining the raw product, S *cp is the cost of obtaining the conditioned product, Srb is the cost of returning the processed heat-transfer agent into the reinjection bore holes, and See is the cost of the electrical energy obtained. A comparison of Eqs. (1) and (2) shows that the cost of the products obtained by traditional and geothermal technologies, is different. The component Sd in Eq. (2) corresponds to the sum of the first three components Spp + Seo + Scr in Eq. (1), and its value is 2 – 3 orders of magnitude less. The sums of the terms (Srp + Scp) and (S *rp + S *cp ) in Eqs. (1) and (2) are comparable in value [6]. With an obvious tolerance we can equate the components Sw in Eq. (1) and Srb in Eq. (2). When using the resources of geothermal heat-transfer agents the cost of the mineral produce obtained is reduced due to the production of the electrical energy obtained from the thermal potential of the heat-transfer agent. Simultaneously, the extraction of valuable components from the heat-transfer agent increases its technological value, since it leads to a reduction in the corrosion of the power station equipment and solves ecological problems. A qualitative analysis of Eqs. (1) and (2) produces an optimistic picture of the potential development of the complex use of the resources of geothermal technologies. Unfortunately, this effect is reduced by a number of problems: the lack of appropriate infrastructure close to geothermal deposits and the electric power stations, as a result of which the work has to be carried out by a shift method; the deposits of geothermal heat-transfer agents developed at the present time have concentrations of the valuable components that are of poor quality; there are no materials which could provide the possibility of enriching the deposit of geothermal heat-transfer agents with a temperature higher than 300°C and operating with them; the lack of reliable equipment. The existing technological systems of geothermal electric power stations in Russia do not enable the thermal potential of geothermal sources to be used completely. The sources, in the form of a steam-water mixture from the bore hole, are fed into separators, where they are divided into working steam, which is fed to the turbines of the geothermal
TABLE 1. Characteristics of electric powers stations based on renewable energy sources (in the world at the end of 2000) Electric power stations Geothermal Wind Solar Tidal
Cost of 1 kW × h, cents
Installed power, MW
IPUF, %
10,200 12,500 50 34
55 – 95 20 – 30 8 – 20 20 – 30
today
in the future
Cost of 1 kW of installed power, dollars
2 – 10 5 – 13 25 – 125 8 – 15
1–8 3 – 10 5 – 25 8 – 15
800 – 3000 1100 – 1700 5000 – 10 000 1700 – 2500
Fraction of the Growth in the last electric power five years, % produced, % 70.2 27.1 2.1 0.6
22 30 30 –
A Method of Increasing the Operating Efficiency of Geothermal Electric Power Stations
electric power station, and the remainder, which is dumped into the ground or into reinjection bore holes drilled into the rocks. It is necessary to take into account the fact that the temperature of the steam and of the separated material is the same after the separation. The use of the thermal potential of the jettisoned separated material should enable the operating efficiency of the geothermal power station to be increased. Unfortunately, the mineral component of the geothermal separated material prevents this: when its temperature is reduced the formation of hard mineral deposits in the thermal power equipment increases sharply. In addition, the preservation of the high temperature of the separated material does not enable blockage of the reinjection bore holes by solid mineral deposits to be prevented, the removal of which involves considerable financial costs. Moreover, as experience with the Mutnov geothermal deposit has shown, the pumping of the separated material into rocks leads to a reduction in the thermodynamic potential of the deposit of hydrothermal heat-transfer agents. It is found that the presence of a mineral component in the geothermal heat-transfer agent does not enable the thermal potential of the working material in the power station to be effectively used, it leads to high additional costs in cleaning out the reinjection bore holes from mineral deposits and it reduces the energy potential of the geothermal location as a whole. The removal of the mineral component from the geothermal heat-transfer agent would enable all these problems to be solved, particularly in the case when it is possible to use the chemical compounds obtained in the national economy. For the Mutnov geothermal site such a chemical compound can be silica, the mass content of which is 70% of the mass of the mineral component of the heat-transfer agent. Developments are taking place in world practice to increase the efficiency of the use of the thermal resource of the geothermal heat-transfer agent by using binary equipment [7, 8]. For example, in the New Zealand geothermal electric power station 3500 t/h of separated material at a temperature of 130°C is pumped into reinjection bore holes. The content of silica in this separated material has reached 1000 mg/l [7, 8]. The effective extraction of SiO2 by chemical methods is feasible at a temperature of 87°C, and hence the design of the geothermal power station was modernized. The separated material, after the separators, at a temperature of 130°C and a flow rate of 972.2 kg/sec, is fed into primary heat exchangers of binary form, where it is cooled to a temperature of 87°C, and the heat is transferred to a 16 MW binary-cycle gas turbine. The separated material is then fed into equipment which extracts the silica, where a reduction in the total SiO2 content occurs down to the solubility of amorphous silica. It is potentially possible to produce 7500 t/year of SiO2 at one site and 3000 t/year at another site, giving an annual gain of 9,750,000 dollars and 3,900,000 dollars respectively. After removing the silica the separated material at a temperature of 85°C is passed through a system of heat exchangers where it transfers 180 MW of heat to river water
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flowing at the rate of 12600 t/h and heats it to a temperature of 38°C. The heat of the water is used to maintain the temperature in ponds containing shrimps. The removal of the silica enables technology to be used to obtain up to 300 t/year of lithium, the value of which amounts to 18 million dollars per year. The separated material, cleaned of chemical compounds, after the heat exchangers is pumped into the rocks at a temperature of 40°C through reinjection bore holes [8]. Hence, a systems approach enables an additional 16 MW of electrical energy to obtained, as well as 180 MW of thermal energy and about 32 million dollars per year from silica and lithium. The thermal power systems of the Mutnov and Verkhne-Mutnov geothermal electric power stations with extractive bore holds are situated at the limits of the eroded structure of the Zhirov volcano, which is part of the Mutnov volcanic region. The region is situated 70 km south of Petropavlovsk-Kamchatka and can serve as an example of the inter-relationship between different forms of modern volcanic and hydrothermal activities [9]. Here there is a complex volcanic system of different ages with powerful fumarol fields, and the Gorelyi volcano with a caldera at the summit of an ancient cone and an active stratovolcano in it, and the ruptured Zhirov volcano with a thermally developed and eroded crater, the total thermal power of which is estimated to be 5000 kcal/sec. There is a narrow depression in the submeridional direction, broken by a network of tectonic imperfections. Within the zone there are manifestations of recent thermal activity, which are briefly described in [9]. The Mutnov geothermal electric power stations operate using geothermal heat-transfer agents with quite a low mineral content, similar in composition to the New Zealand heat-transfer agents. The mineral composition of the Mutnov power station No. 1 separated section, the pH of which varies in the range 8.5 – 9.6 is shown below: Component +
K Na+ NH+4
Ca +2
Mg+2 Fetot Cl– HCO-3 SO24 H4SiO4 H3BO3
Content, mg/l 46 – 55 252 – 278 0.6 – 0.8 2.4 – 3.8 < 0.1 < 0.3 212 – 238 35 – 48 3.9 – 5.6 986 – 1180 74 – 98
It was decided to use the experience gained in the operation of the New Zealand power stations in the Mutnov geothermal electric power stations. To extract the silica from the separated section we chose to use an electodialysis method [10]. Experiments were carried out on a bench, a sketch of which is shown in Fig. 1, and a photograph in Fig. 2.
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7
6
9 10
3
4
13 11
2
8
16
5
15
12
14
17 1
Fig. 1. Sketch of the experimental arrangement for extracting silica from the separated part of the geothermal heat-transfer agent: 1 is a settling chamber, 2 is the main pipeline for draining off the separated material from the electrodialyser, 3 is a valve, 4 is a cathode plate, 5 is a porous membrane, 6 is the power supply, 7 is a dc source with voltage and current regulation, 8 is the main feed of the separated material from the heat exchanger to the electrodialyser, 9 is a heat exchanger, 10 is the main feed of the separated material from the separator, 11 is a connecting pipe for feeding in cooling water, 12 is a connecting pipe for leading out cooling water from the heat exchanger, 13 is an anode plate, 14 is a connecting pipe for the outflow from the anode chamber of the electrodialyser, 15 is the precipitated suspension of colloidal silica with different chemical compounds, 16 is a drain pipe from the cathode chamber of the electrodialyser and 17 is a pipe for draining off the cleaned separate from the system
Fig. 2. Photograph of the experimental equipment for extracting silica from the separate of the geothermal heat carrier.
The separated section was at a temperature of 170°C and it was necessary to reduce its temperature to less than 100°C in order to carry out experiments. This was done in the pipe heat exchanger 9. Tap water at a temperature of 8°C was used as the cooling agent and was introduced into the heat
exchanger through a connecting pipe 11 and poured out through the nozzle 12. The flow of cooling water and the separated material was regulated by means of valves 3. Two zones with different values of pH are produced in the electrodialysis tank, separated by a porous membrane: in the cathode zone pH > 7 (during the course of the experiments the values of the pH in the cathode zone reached 11.2), while in the anode zone pH < 7 (during the course of the experiments the values of the pH in the anode zone reached 1.7). As a result of this, due to the low values of the pH in the anode zone, rapid separation and precipitation of colloidal silica with a mass content of salts of the accompanying metals from 5% to 20% occurred. We used wafers of different porous materials as the membranes. The pore dimensions of these enabled dynamic silica precipitation processes to occur with a flow rate of the solution in the electrodialysis tank of 0.005 – 0. 02 m/minute. The volume of the electrolysis tank was 54 l, the area of the aluminum electrodes was 0.08 m2 each, the area of the porous membrane was 0.09 m2, the membrane thickness was 4 mm, the dc voltage from the power supply was 0 – 38 V, the current was 0 – 10 A and the distance between the electrodes was 0.5 m. When carrying out the experiments under static conditions, the equipment functioned as follows: the electrodialyser tank was filled with separate at the required temperature, which was kept constant throughout. A dc source was then connected to it. Using a voltmeter and an ammeter the required voltage and current strength was established and the temperature of the liquid and the concentration of SiO2 in the electrodialyser were measured every five minutes. At the end of the experiments the solution, together with the precipitated silica, was poured off through the tube 16 (Fig. 1) of the lower feed pipe into a settling chamber 1. After the settling process was completed the water was drained through the drainage tube 17, and the residue was centrifuged and then dried in a vacuum drier. When conducting experiments under dynamic conditions, the flow rate of the separate and the cooling water through the electrodialyser and the heat exchanger 9 was measured using a measuring cylinder and a timer in the drain through tubes 12 and 17. During the experiments, using a platinum-rhodium thermocouple, the readings of which were recorded on a Mastech MY-64 multimeter, we recorded the temperature of the cooling water at the entrance and exit, and also of the heat-exchanger surface, which enabled us to calculate the mean-integral values of the heat-transfer coefficient a of the heat exchanger, representing its operating efficiency a = amp/acs , where amp and acs are the heat-transfer coefficient of the heat exchanger with mineral precipitates and without mineral precipitates respectively, W/(m2 × K).
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100 80 60 40 20 0 20
30
40 50 60 70 80 Temperature of the separate, °C
90
Fig. 3. Effect of the temperature of the separate on the degree of extraction of colloidal silica by electrodialysis in 15 minutes.
1.0
heat-transfer coefficient a, rel. units
The total and dissolved silicic acid was determined spectrophotometrically. The optical density was measured on an SF-46 spectrophotometer. For a silicon content in the solution of 0.05 – 1.5 mg/kg it was determined in the reduced form of blue silicon-molydenum heteropoly acid (l = 815 nm), and for a content of 3 – 30 mg/kg it was determined in the form of yellow silicon-molybdenum heteropoly acid with l = 415 – 425 nm. If the content of the silicic acid exceeded 30 mg/kg, a dilution method was employed. The experiments carried out on the extraction of silica from the separate at different temperatures (from 20°C to 95°C) enabled us to determine the temperature range of effective operation of the electrodialyser (Fig. 3). It can be seen from the graph (Fig. 3), that maximum precipitation of silica occurs in the 78 – 84°C temperature range. At other temperatures the degree of coagulation of the colloidal silica falls. At the same time, an analysis of the operation of the heat exchanger of the experimental equipment showed a sharp drop in the heat-transfer coefficient during the course of experimental investigations (Fig. 4), which can be explained by the increase in the solid mineral precipitate on the heat-exchanger surfaces in the temperature range in which the experiments were carried out. In fact, examination of the heat exchanger showed that, after a week of experiments, the heat exchanger surface was covered with “mineral fur” up to 10 mm thick. To eliminate deposition of mineral sediments on the heat exchanger surfaces it is necessary to change the pH of the overall mass of the separate (about 1000 t/h) by chemical methods, which is best done as in New Zealand. For the conditions of the Mutnov geothermal electric power station this method is not economically justified since it involves considerable costs not only in purchasing reagents (we are speaking of tens of thousands of tons per month), but also their delivery from other regions, since Kamchatka does not have appropriate mineral resources to produce them (for example, limestone deposits). The existing technological system of the Mutnov geothermal electric power station consists of units for separating the steam-water mixture of the geothermal heat-transfer agent into steam, which enters the turbine and contains practically no mineral component, and a water separate, in which the chemical compounds are dissolved. An increase in the energy efficiency of the power station is possible using the following programs: 1. The use of the thermal energy of the separate. In this procedure, which uses a special expander, the design of which is based on engineering methods obtained as a result of research carried out in [11], the separate is boiled up and expanded while the temperature falls from 170°C to 80°C. The steam obtained enters the “exhaust steam” turbine with the electrical generator. The waste steam is fed to a mixer-type condenser. The condensate obtained is cooled in an evaporator and is fed in the form of a cooling agent into the mixer-type condenser. Preliminary calculations show that
Degree of extraction of SiO2, %
A Method of Increasing the Operating Efficiency of Geothermal Electric Power Stations
0.8 0.6 0.4 0.2 0
0
50
100 Time, h
150
200
Fig. 4. Change in the mean-integral heat-transfer coefficient a during the experiments.
the use of the thermal energy of the secondary steam increases the power of the station by 20 – 25%. 2. Obtaining conditioned products by purifying the secondary separate from chemical compounds. The secondary separate is purified from chemical compounds by chemical or electrochemical methods [12]. As a result one obtains raw silica, contaminated with 15 – 20% of the components mentioned earlier, which can be quite easily extracted by washing with acid. After drying under laboratory conditions one obtains finely dispersed silica with a purity of 99.8%. This is a merchandisable product, which has wide applications in the form of a supplement in the chemical and lacquer-dye industry, in the production of high-quality paper and rubber, and in electronics in the production of silicon batteries. Depending on the purity of the silica its cost can vary from 2 to 20 thousand dollars per ton [12]. The production of pure silica enables the cost of cleaning reinjection bore holes and the technological equipment from hard mineral deposits to be reduced and consequently increases the operating efficiency of the power station. The potential production of silica from the heat-transfer agent of the Mutnov power station amounts to 3000 – 4000 t/year. 3. The use of thermal energy of the secondary separated material. The secondary separated material, purified from chemical compounds, having a temperature of the order of
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5 2
3 4 1
6
4 5
8
7 10
11
13
9
5 12 14 15 18 20
19
22 21 23
17
16
Fig. 5. The basic technological arrangement for using geothermal resources based on the existing Mutnov geothermal electric power station No. 1: 1 is the steam-water mixture supply line, 2 is a separator, 3 is the turbogenerator, 4 is a mixer condenser, 5 is a supply pump, 6 is a water cooler, 7 is an “exhaust steam” turbogenerator, 8 is an expansion tank, 9 is an electrodialyser, 10 is a settling tower, 11 is a condenser, 12 is a main line for pumping processed water into the rejection bore holes, 13 is a tubular heat exchanger, 14 is a binary-cycle turbogenerator, 15 is a container with low-boiling-point working agent, 16 is an air cooling tower, 17 is a blower air ventilator, 18 is a valve for discharging air, 19 are reactors for carrying out silica purification and washing, 20 is a thickener, 21 is a vacuum drier, 22 is a vacuum pump and 23 is a vessel for collecting dry dispersed silica.
80°C when choosing an appropriate low-boiling point working agent and developing a special binary unit, can be used to obtain electrical energy. Preliminary calculations show that the use of thermal energy of the secondary separated material enables the power of the station to be increased by 3 – 5%. The cooled separated material with a temperature of 20 – 25°C, containing the products of the removal of chemically pure silica in a concentration of 0.01%, can be pumped into the rocks through reinjection bore holes, and can be dumped onto the river bed of the Fal’shiv river, depending on the profitability of the process. The absence of silica in the
water and the low concentrations of chemical compounds prevents the reinjection bore holes from being blocked by solid deposits, and helps to prevent harmful action on the environment when the processed aqueous solution flows away. In view of the possibility of introducing the above programs, we propose the basic technological system shown in Fig. 5 for using the resources of geothermal heat carriers, based on the existing Mutnov geothermal electric power station No. 1. According to the proposed arrangement, the steam-water mixture in supply line 1 is fed into the separator 2, where it is separated into steam and the residue; the steam is fed into the turbine of turbogenerator 3. The processed steam is condensed in a mixer-type condenser 4 and is fed via a supply pump 5 into a water cooling tower 6, where it is cooled. The condensate from the cooling tower is fed as a cooling agent into the condenser 4. As the condensate builds up, its surplus is removed from the cooling tower into sinks. The separated material from separator 2 is fed into an expander 8, where it is separated into a secondary separate and secondary steam; the secondary steam is fed into the “exhaust steam” turbine of the turbogenerator 7. The excess of condensate, obtained in the water-cooling tower, is fed into the reinjection bore holes for pumping into the rock. The secondary separated material from the expander 8 is fed into the electrodialyser 9, where silica ash is formed containing different chemical elements. The secondary separated material with the ash is then fed into a settling tank 10, where silica gel is formed, which separates out in the coagulator 11. The purified secondary separated material is fed into the binary-cycle tubular heat exchanger 13, where the heat is delivered to a low-boiling point working agent, converting it into the vapor phase, and after the heat exchanger it is pumped along the supply line 12 into the rock through reinjection bore holes. The steam of the working agent is fed into the turbine of the binary-cycle turbogenerator 14. After the turbine the agent enters a hermetically sealed tubular air cooler 16 and, being condensed in it, again enters the heat exchanger. The colloidal solution of raw silica, after the thickener 11, enters the reactors in which the silica is cleaned and washed 19. The solutions of silica with chemically contaminating compounds are fed into the supply line 12. The cleaned colloidal SiO2 is fed into the thickener 20, then into a vacuum drier 21, and in the form of chemically pure finely dispersed powder is collected in the vessel 23 as a commercial product. The “Geoterm” Joint Stock Company is actively engaged at the present time in scientific research and development to design programs for increasing the utilization efficiency of the thermal energy of the separated material and to obtain dispersed silica by purifying the secondary separated material from mineral components. Calculations have shown that it is possible to increase the power of the Mutnov geothermal electric power station by 28 – 30% when it is modernized using the scheme proposed above. The operating throughput
A Method of Increasing the Operating Efficiency of Geothermal Electric Power Stations
should increase by 5 – 8%, which makes the project quite profitable. CONCLUSIONS 1. We have presented a brief review of the state of geothermal electric power engineering in the world and in Russia. 2. We have shown, on the basis of theoretical and experimental investigations, that a complex approach is necessary both to the heat carriers and sources of mineral raw material if one wishes to increase the utilization efficiency of geothermal resources. 3. We have analyzed the state of the Mutnov geothermal electric power station with the idea of modernizing it by a wider use of the geothermal resources. We have proposed a technological system for increasing the operating efficiency of this electric power station. REFERENCES 1. O. A. Fomina, An alternative from the depths. TEK “Energy Saving and Energy Efficiency”, No. 12 (2005). 2. A. A. Salamov, Geothermal power plants in world power engineering, Teploenergetika, No. 1 (2000). 3. A. B. Alkhasov and V. I. Radzhabov, “A method of increasing the utilization efficiency of geothermal heat,” Teploenergetika, No. 3 (2003).
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4. K. Ya. Kondrat’ev and V. F. Krapivin, “The present state and future prospects for the development of world power eingeering,” Énergiya, No. 2 (2006). 5. O. V. Tsarnizhevskii, “The present state and future prospects for the use of renewable energy sources in Russia,” Promyshl. Energ., No. 1 (2002). 6. V. P. Myazin, T. P. Belova, A. S. Latkin, et al., A Geotechnological and Physico-Chemical Estimate of the Mineral and Nontraditional Type of Raw Materials of the KuriloKamchatka Region [in Russian], Poisk, Chita (2002). 7. R. T. Harper, I. A. Thain and J. H. Jonston, “Towards the efficient utilization of geothermal resources,” Geothermics, 21, No. 5/6 (1992). 8. R. T. Harper, I. A. Thain and J. H. Jonston, “An integrated approach to realize greater value from high-temperature geothermal resources: a New Zealand example,” Proc. World Geothermal Congress, Florence, Italy (1995). 9. V. M. Sugrobov, V. I. Kononov and O. B. Vereina, “The prospects for the utilization of the Kamchatka geothermal resources,” Vulkanologiya i Seismologiya, No. 1 (1991). 10. A. S. Latkin, V. E. Luzin, B. E. Parshin, et al., Russian Patent No. 2322889 (RF). A method of extracting silica from a hydrothermal heat-transfer agent. 11. A. S. Latkin, Heat and Mass Exchange in Swirling Flows [in Russian], Izd. RUK Petropavlovsk-Kamchatskii (2007). 12. R. Ailer, Silica Chemistry [Russian translation], Mir, Moscow (1982).
