Geothermal Power Plants In The Philippines 3f6mf

Geothermal Power Plants in the Philippines

Plant Name Location

Owner/ Operator

Steam Supplier

Date Rated Commi Capacit Remarks y ssione (MW*) d

Luzon Makban Plant A

Bitin, Laguna

NPC

Makban Plant Bitin, Laguna NPC B Makban Plant C

Bitin, Laguna

NPC

Makban Plant Bitin, Laguna NPC D Makban Plant E Tiwi A Tiwi B Tiwi C Bacman A BacMan (Cawayan) Bacman (Bacon)

Bitin, Laguna Tiwi, Albay Tiwi, Albay Tiwi, Albay Bacon, Sorsogon Bacon, Sorsogon

NPC NPC NPC NPC NPC NPC

Chevro n Chevron Chevro n Chevron

110 110 110 40

Chevro n

40

Chevron

110

Chevro n Chevron PNOCEDC PNOCEDC

110 110 110 20

1979 1980 1984

On prolonged shutdown

1995 1996 1979

decommissioned

1980 1981-82 1993 1994

Bacon, Sorsogon

NPC

PNOCEDC

20

1998

Valencia, Negros Oriental

NPC

PNOCEDC

112.5

1983

Visayas Palinpinon I

Valencia, Palinpinon 2 Negros Oriental Northern Negros Leyte A & B

Negros Occidental Tongonan, Leyte

NPC PNOCEDC PNOC-EDC

PNOCEDC PNOCEDC PNOCEDC

80

49 610.18

1993-95

2007 1996

On rehabilitation NPC-IPP

Plant Name Location

Leyte Tonginan

Owner/ Operator

Steam Supplier

Date Rated Commi Capacit Remarks y ssione (MW*) d

Kananga, Leyte

NPC

PNOCEDC

112.5

1983

Kidapawan , N. Cotabato

Marubeni Corporatio n

PNOCEDC

54.24

1996

Kidapawan, N. Cotabato

Marubeni Corporation

Mindanao Mt Apo I

At Apo II

PNOCEDC

54.24

1999

NPC-IPP

NPC-IPP

Working of Geothermal Power Plants For the generation of electricity Geothermal power plants use much higher temperature deep within the earth, we can say that these power plants are much similar to coal or oil powered generators in which electricity is generated from steam driven turbines. One of the main difference is that coal and oil powered plants burn fossil fuels to produce steam while the heat of the earth’s core is used by the geothermal power plants. Earth’s core is extremely hot and some areas are more suitable for the generation geothermal power from others depending upon that how far the surface of hot areas are located in the within the earth. Places where high incidence of volcanoes occurs are much suitable for the production of geothermal energy. As we have heard about geysers, hot springs and volcanoes, these are the examples from in which the molten core comes close to the surface. From ancient times heat from hot springs has been used for the generation of geothermal energy. There is a simple concept behind generation of geothermal power. To tap into a pressurized area of hot water and steam drill a hole deep into the earth and to drive a turbine for the generation of electricity we have to pipe the steam to the surface.

Direct Steam Plants It is the oldest type of geothermal power plants, operates as I described above. Underground collection of hot water and steam are tapped and steam used to turn turbines. The concept of generating electricity form the heat of earth is not new, a direct steam powered generator is used by Prince Piero Conti of Italy to light a few light bulbs at the steam fields of Larderello and after seven years a commercial power plant was built at the same location. There are few potential problems of Direct steam plants which are discussed below, 



Steam which is used for the driving of turbines may carry small amounts of mineral, which can make steam to be very corrosive to the turbine, and due to this the possibility of releasing pollutant into the air also increases. One other problem is that there are limited number of locations have the geological structure which is important for the feasibility of Direct steam plants.

Other type of plants that overcome some of the problems and are widely available have developed by the engineers. Possible pollution reducing because current plants recover the condensed steam and return it to earth. Binary power plant is the newest system and geothermal fluid es through heat exchanger in this system. In this exchanger, the transfer of earth’s heat to another fluid circulating in a closed system takes place and this fluid vaporizes to steam, drives the turbines and then condenses to liquid, after it the cycle starts again. These type of systems avoid turbine parts to the corrosive steam and eliminates pollution virtually. We can say that, Binary systems will probably be the most common in the future.

Present and Future of Geothermal Power Plants Currently, there are 24 countries in the world which have geothermal generating plants, others are more likely to follow as the technology improves and the problems with oil become more apparent. The US has the highest absolute production and producing almost 3000 megawatts and this is very small according to the needs of the country. Many of the geothermal plants are in California and they only produce about 5% of the energy needed by the state. Second largest producer of geothermal energy is Philippines.

According to the estimation of Earth Policy Institute, there are at least 39 countries that meets their electric needs with the production of geothermal and many more can use geothermal as part of their energy mix. It can be concluded that Geothermal power plants are a cost effective source of electric power that are likely to become more common in the future.

Geothermal Energy Due to Sun The top surface of the earth is baked by the sun during the day. The earth conducts this heat underneath the surface. The effect of this is more pronounced during the winters – when the temperatures a few meters underground are 10-15 degrees Celsius. Geothermal Energy from the Earth’s Core

The other source of geothermal energy is the hot center of our earth. The center of the earth has very high temperature of up to 6000 Celsius. Places which are more prone to volcanic eruption are mostly suitable for extracting geothermal energy. The hot pools and geysers are other apparent forms of geothermal energy at our disposal. The geothermal energy from the center of earth can be extracted by digging for deep pipelines which will require more cost. Comparison of the Two Sources The geothermal energy due to absorption of heat from sun rays is more uniform and can be used anywhere. This heat is mostly used to warm up the homes in cold countries.

Different Scandinavian countries have employed methods which make use of this energy. However the geothermal energy from the earth’s center is more useful when higher temperatures are required; for example, in generating steam for power plant usage. Mechanism Employed

The water needs to be pumped for circulating through the pipes. This pumping cycle needs electricity or some mechanical power. However it is estimated that you get 2-3 degrees for using one degree equivalent power. This heat can be extracted by laying underground pipes and running water through them. Applications The water absorbs heat which can be used for different purposes after reaching the earth’s surface. This water can be directly used for floor heating using compressors. The water containing the geothermal energy needs less heat to boil. So this water is more economical in generating steam which in turn can be used for electricity or supplying hot water to buildings. As less fuel is consumed in heating this underground water so the drastic effects on environment can also be reduced.

A geothermal power plant consists of a geothermal steam source, vaporizer, mist separator . The other major parts are just the same as a conventional thermal power plant, such as:: [1] steam turbine, generator set. Control room and circuit breakers are included. (2) condenser and condensate tanks. Hoy water,93deg C may used for other purposes such as health spas with a heat exchanger. Colder water is injected back to the source wells.

How the plant works A mixture of steam and geothermal brine is transported from the wells to a central separation station. After being separated from the brine, the steam is piped through moisture separators to steam heat exchangers inside the plant building. The steam can be piped to steam turbines for co-generation of electricity. Unutilized steam is released through a steam exhaust. In the steam heat exchangers, the steam is cooled under pressure into condensate whose heat is then transferred to cold fresh water in condensate heat exchangers. The condensate cools down in the process to 20°C. Separated geothermal brine has its heat transferred to cold fresh water by geothermal brine heat exchangers. Since the mineral-rich geothermal brine causes scaling that coats the heat exchanger pipes, steel particles are allowed to circulate in the stream, impacting against the pipes to remove any scaling as it occurs. Cold water is pumped from wells at Grumelur, near the shore of Lake Thingvallavatn, to a storage tank by the power house. From there, it is pumped to the heat exchangers where its temperature is raised to85-90°C. Since the fresh water is saturated with dissolved oxygen that would cause corrosion after being heated, it is ed through deaerators where it is boiled at low vacuum pressure to remove the dissolved oxygen and other gases, cooling it to 8285°C.

The heating process Heat exchangers Hitaveita Reykjavikur operated a pilot heating plant at Nesjavellir during 1974 - 1990. Various types of heat exchangers have been tested. Conventional plate heat exchangers are used for the condensation of steam from the separators and to cool the condensate. They are equipped with EPDM-gaskets and made of titanium plates to avoid stress corrosion, as it is not possible to guarantee problem free operation if stainless steel plates are used.

Conventional heat exchangers cannot be used for the separated water due to the high content of dissolved solids (TDS 1200 PPM) which would cause severe scaling of silica. A new type of heat exchanger, in the geothermal context, has been tested successfully in the pilot plant. These are the so-called "fluidized bed heat exchangers", or FBHX made by Eskla Heat exchangers BV in the Netherlands. They are shell and tube heat exchangers operating in a vertical position . Stainless steel balls, 1.5 mm in diameter, circulate in the flowstream of the separated water. They impact continuously against the pipe surfaces and remove any scaling that may form. A mechanical device is fitted to the inlet and outlet of the heat exchangers to keep the steel balls evenly distributed in the flow stream. The FBHX heat exchangers make possible the direct utilization of the heat in the water from the separators and contribute to the overall economy of the heating process. Deaeration The cold ground water is saturated with dissolved oxygen and becomes very corrosive when heated. A conventional thermal deaeration method is used where the ground water is boiled under vacuum after heating to remove the oxygen. The cold ground water has a pH-value of 7.5-8.5. It is partially degassed through boiling after heating. This raises the pH-value to 9.0-9.5 and the oxygen content is reduced down to about 50 ppb. The remaining dissolved oxygen is removed through injection of small amounts of geothermal steam that contains acid gases (H2S and CO2). Hydrogen sulfide gas reacts rapidly with the dissolved oxygen. The final water product then has a pH-value of 8.5-9.0. It is free of dissolved oxygen, and contains 0.5-2.0 PPM of H2S. The remaining H2S gas reacts against any oxygen absorption in accumulators and ensures that the "pleasant smell", which the s of geothermal water in Iceland have become accustomed to, is retained.

Amorphous Mg-Si scaling was formed in the distribution system in Reykjavik during the first months of operation of the plant, due to the high pH-value of the mixture of the geothermal water from the low-temperature fields and the heated ground water from Nesjavellir. Different ratios of these two water types control the pH-value. Scaling can only be avoided by reducing the amount of geothermal water in the mixture below 10-

15%. Therefore the original plan of mixing these two water types in the distribution network has been abandoned. They will be used separately. The waste geothermal water Geothermal heating plants in high-temperature fields only utilize the thermal energy of the geothermal fluid, which, after use in heat exchangers. must be disposed of with minimum risk to the environment. This disposal can be performed in two different ways, i.e. at surface or into subsurface aquifers. Surface disposal can be carried out in a similar way to the natural disposal of flow from the hot springs, i.e. into the brook in the Nesjavellir valley, which disappears into a lava field before reaching Lake Thingvallavatn. Subsurface disposal requires that the waste water is pumped back into the geothermal reservoir. This latter method is obviously more friendly to the environment but more expensive. It can also be more difficult to operate due to scaling in the reinfection wells and their aquifers. There are two important features of the waste water from high-temperature fields that may have a negative effect on the environment. These are the raised temperature of surface waters and ground water aquifers and the presence of hazardous chemicals in the waste water, i.e. arsenic, mercury, boron, etc. Extensive research has been carried out at Nesjavellir with respect to disposal of the waste water. Chemical and biological measurements have been carried out at Lake Thingvallavatn since 1979 to define the pre-exploitation value for future reference. All the wells at Nesjavellir were flow tested in 1984-1987 as a part of the exploration program. Large amounts of geothermal water were disposed of at the surface during these tests without any apparent effects on water chemistry at the shoreline of the lake. This is in agreement with the prediction of a ground water model that simulates fluid flow and distribution of chemicals in the ground water system at Nesjavellir. Chemical analysis of the geothermal fluid show that dangerous chemicals, which may be expected from the condensate of the steam phase, are almost absent. All arguments seem to indicate that surface disposal of the waste water can be used for the geothermal power plant at Nesjavellir. THE GEOTHERMAL POWER PLANT General outline

Due to scaling, the geothermal fluid from the Nesjavellir field cannot be used directly in the space heating distribution network. The power plant therefore uses the geothermal energy to heat cold ground water indirectly in heat exchangers. The heated water is treated so that it can be used directly in the network. The geothermal power plant at Nesjavellir consists of the following five sub-systems all of which have separate functions: 

Cold water supply

   

Geothermal fluid supply Heating and treatment of cold ground water Transmission pipeline to Reykjavik Electricity co-generation

These five sub-systems of the power plant are described below along with their main functions. The planned capacity of the co-generation power plant is 400 MA for district heating and over 80 MWe when fully developed. The design is for two power stations of similar size which will be developed in steps as follows: Power station I: Phase 1: 100 MWt Phase 2: 100 MWt + 8 MWe Phase 3: 30-37 MWe Power station II: Phase 4: 100 MW, + 23 MWe Phase 5: 100 MWt + 23 MWe The first phase of power station I became operational in September 1990 but the second phase is being built in two steps in 1991 (already in operation) and 1993. The cold water supply Cold ground water (4°C) is pumped from 30 m deep wells, at Gramelur, 6.2. km north of the power house, in a lava field at the shore of Lake Thingvallavatn. The nominal capacity of each pump is 278 kg/s, but larger pumps can be installed. Four wells have been drilled so far with only 5 m spacing. Pumping tests of up to 600 kg/s have confirmed a very high permeability of the lava formation. The pumping station is designed so that it can be enlarged for future developments and house additional wells. The cold water is piped 6.2 km through a DN 900Æ mm pipe from Gramelur to the power house. The pipe is made of ductile iron and has the same capacity as the transmission pipeline to Reykjavik, i.e. about 1900 kg/s. The water is piped to an 1000 m3 storage tank by the power house, before entering the heat exchangers and deaerators.

The geothermal fluid supply The geothermal fluid supply system gathers the fluid from the production wells, separates water and steam and then pipes them individually to the power house. Figure 15 shows a schematic flow diagram of the system. It includes two phase pipes from the production wells, separators, pressure control valves and the mist eliminators by the power house. The wells discharge a mixture of water and steam, which is transported along the twophase pipes to a central separator station close to the power house instead of a number of separators nearer to the wells. The two-phase pipes are therefore relatively long, which is made possible by the high enthalpy of the well fluid and favorable topography. The dissolved solids are largely confined to the separated water phase, as steam and water are almost completely (over 99.9%) separated in the separators. The separator station is situated 400 m away from the power house. The separated steam pipeline is constructed so that some condensation occurs in the pipe. The condensate washes out remaining dissolved solids in the steam. It is drained through control valves on the pipe and the remaining droplets are removed in the mist eliminators. Three wells (no. NJ-11, 13 and 16) are connected to the separator station for the first phase, with well NG-6 as a reserve. These wells have a very high steam fraction (enthalpy 2000 kJ/kg). It was therefore decided to operate the steam separators at 15 bara, which is an unusually high pressure for a geothermal power plant. The advantages are smaller pipes and more efficient electricity generation. Power station II will utilize wells with lower fluid enthalpy and a lower separator pressure will be more practical, probably 8 bara. Vertical separators have hitherto been chosen for steam separation in geothermal power plants. Nesjavellir is the first one to operate conventional horizontal separators with Chevron-filters, their main advantages being less height, hence lower cost for separator building and much easier water level control. The capacity of each separator equals 35 kg/s or about 50 MWt (at 15 bara). The mist eliminators are in principle of the same size and type (horizontal) as the main separators but are fitted with "wire-mesh" filters. No steam turbine is installed in the first phase of the power plant. The steam pressure must therefore be lowered in control valves from 15 to 2 bara before entering the heat exchangers. This causes superheating of the steam and very high noise level due to sonic flow. The control valves are therefore placed in a separate building. Here, condensate is injected into the superheated steam to cool it to saturation conditions to protect the gaskets in the plate heat exchangers. Electricity generation is planned in phases 2 and 3. The high pressure steam will then expand in back pressure turbines, down to 2 bara, relieving the control valves of the

high flow load. The exhaust steam from the turbine will be piped directly to the heat exchangers. The heat exchangers The indirect heating of the cold ground water takes place in the heat exchangers. About 82% of the heat is transferred in the steam heat exchangers. The condensate heat exchangers cool the condensate from the steam heat exchangers down to 20°C and add about 14% to the heating process, whereas the heat exchanger for the separated geothermal water finally contributes only 4% to the heating in the first phase of the power plant. Steam heat exchangers. Three out of four of the installed steam heat exchangers have titanium plates, but one of the heat exchangers has plates of ANSI 316 stainless steel for testing the long-term corrosive resistance of this material. The steam temperature is kept below 120°C (2 bara), the maximum temperature that the EPDM material in the gaskets can withstand for a longer period. They are manufactured by REHEAT in Sweden. Each titanium heat exchanger is composed of 329 plates with a total heat exchange surface area of 280 m2, whereas the stainless steel heat exchanger has 367 plates and heating surface of 312 m2. The heat transfer coefficient is stated to be 4300 W/(m2K) for clean plates. Condensate heat exchangers. The condensate heat exchangers are of the conventional plate type. They extract the heat of the condensate from the steam heat exchangers through cooling from about 90 to 20°C. Two heat exchangers connected in parallel were installed in the first phase of the power plant, one acts as a reserve. They are manufactured by REHEAT of Sweden. The plates are made of the ANSI 316 stainless steel and have a heat exchange surface area of 190 m2 Heat exchangers for the separated water. There are two fluidized bed heat exchangers (FBHX) connected in series, which transfer heat from the separated water to the cold ground water. Each FBHX is equipped with 19 steel pipes (ID 50 mm, length 9 m). These heat exchangers contribute only 4% to the heating process of the first phase, as stated earlier. They are therefore installed mainly to obtain operational experience, as

they will play an important role in power station II when the low enthalpy wells will be connected. The separated water is cooled down to 20-35°C before entering the waste water system. Deaeration of the heated water The main role of the two deaerators installed in the plant is to remove oxygen from the heated fresh water. It enters the vessel at the temperature of 85-88°C and is deaerated through boiling by vacuum pressure down to 83°C. The main flow enters the central part of the deaerators. The water boils vigorously as it sprays over the filling material. Steam and gas rise to the top. There the steam is condensed through injection of cold water before the gas is ejected. At the bottom of the vessel a small amount of geothermal steam is injected into the deaerated water to dissolve hydrogen sulfide. This lowers the pH, rids the water of any remaining oxygen and acts against oxygen absorption. The deaerators are made of stainless steel. They are 2.5 m in diameter and 11 m high. The nominal capacity of each is 278 kg/s of heated water or 50% of the first phase. The control system The computerized control system for the geothermal power plant at Nesjavellir is identical to the one that is used to supervise and control the pumping stations for the low-temperature fields and the distribution network in Reykjavik. This control system was tailor-made for Hitaveita Reykjavikur [Magnusson and Gunnarsson, 1989]. The advantage of using the same type of control system is to reduce the investment, training and maintenance costs. The data processors. The control system is built around process computers of the Texas Instruments 565 PC type. They take care of sequence and closed loop controls. They are situated in the cold water pumping station, in the transformer station and in the power house. Two process computers are connected together in the power house in a hot back-up configuration, as they control the most critical part of the heating process. The SCADA System. The process computers are connected to a SCADA system (Supervision Control and Data Acquisition). The SCADA system is based on a PDP 11/83 computer in the control building at Nesjavellir . Peripherals such as color screens and printers are located in the control rooms at Nesjavellir and in Reykjavik . The power plant is operated round the clock from Reykjavik as the control room at Nesjavellir is usually unmanned. The peripherals in Reykjavik are connected to the PDP 11/83 computer through a 64 kbit/s data multiplex and a fiber-optical data link. The color VDU display system used is of the ABB Tesselator type. One of the advantages of this system is that it can be connected to the SCADA computer by modem. The Tesselator system can therefore easily be moved around, which facilitates all process tests and remote monitoring. Should the SCADA system fail, the power plant can be controlled from switch boards that are connected directly to the PC's processors. The operation of the power plant is fully automated. It can run all day without any manual intervention, except during breakdowns. A closed loop control is used at all stages and reserve pumps take over automatically in case of pump failure. Restarting of

the plant after shut-down is at present done manually but automation will be gradually increased as experience is gained in the operation. The process simulator. A computer model has been developed for the dynamic behavior of the plant. It runs on a PC computer and the whole process is incorporated into the model. A lot of effort was made to make the program code as effective as possible for real time simulation. The simulator consists of a PC computer that simulates the process, a process computer with the same software as is used for the control system of the plant and a SCADA system similar to the one used in the power plant. The process computer program had to be modified to communicate with the PC computer instead of the sensors and control system of the power plant. The main advantages of the simulator are expected to be: · The designers and operators can optimize regulation and control strategies in a simple way. Tests that are either too risky or time consuming can be simulated. · Training of personnel can be carried out without disturbing the operation of the plant. Both normal operation and various types of breakdowns can be simulated. · Development of an expert system for operation and maintenance of various parts of the system. Ventilation of buildings The atmosphere at Nesjavellir is contaminated with H2S gas from the geothermal field. Its concentration varies depending on weather conditions, but is estimated to be around 100 ppb on average. H2S is especially corrosive for copper and silver, materials that are common in electrical and electronic equipment. Instruments are therefore largely situated in air-tight buildings . These buildings are fitted with airlocks and an independent ventilation system where the hydrogen sulfide gas is absorbed in active carbon filters. The requirements for the indoor conditions are that the H2S content is below 3 ppb and relative humidity around 40%. This is expected to be achieved with the ventilation system by pressurizing the building up to 100 kPa, recirculating about 85% of the air inside the building and placing the fresh air intake about 6 m above the roof of the power house (20 m above ground level). The power plant buildings have two additional ventilation systems installed. One is for the visitors' reception hall and the other for the process halls. Both of these are conventional systems without gas purification but they use the same fresh air intake.

Geothermal Energy: Operations and Maintenance Impacts Environmental impacts during the operations and maintenance phase would mostly occur as a result of noise, water demand, waste management, land use conflicts, potential spills, and the increased traffic at the project site. Typical activities during the operations and maintenance phase include operation and maintenance of production and injection wells and pipeline systems, operation and maintenance of the power plant, waste management, and maintenance and replacement of facility components. Potential impacts from these activities are presented below, by the type of affected resource.

Acoustics (Noise) Primary sources of noise during normal operations would be associated with the power plant, e.g., the power houses, transformers, and cooling towers. Cooling towers are relatively tall and have noisegenerating fans at the top, making them the main source of noise. During the operations and maintenance phase, a geothermal power plant would generate noise levels in the 71 to 83 decibel range at a distance of one-half mile. Noise levels can be reduced by the addition of mufflers or other soundproofing. The primary impacts from noise would be localized disturbance to wildlife, recreationists, and residents.

Air Quality Emissions generated during the operations and maintenance phase include exhaust from vehicular traffic and fugitive dust from traffic on paved and unpaved roads, most of which would be generally limited to worker and maintenance vehicle traffic. In addition, emissions could include the release of geothermal fluid vapors (especially hydrogen sulfide, carbon dioxide, mercury, arsenic, and boron, if present in the reservoir). Impacts would depend upon the amount, duration, location, and characteristics of the emissions and the meteorological conditions (e.g., wind speed and direction, precipitation, and relative humidity). Carbon dioxide emissions would be considerably less than for comparable power plants using fossil fuel. State and local regulators may require permits and air monitoring programs.

Cultural Resources During the operations and maintenance phase, impacts to cultural resources could occur primarily from unauthorized collection of artifacts and from visual impacts. In the latter case, the presence of the aboveground structures could impact cultural resources with an associated landscape component that

contributes to their significance, such as a sacred landscape or historic trail. The potential for indirect impacts (e.g., vandalism and unauthorized collection) would be greater during the operations and maintenance phase compared to prior phases, due to its longer duration.

Ecological Resources Most impacts to ecological resources (vegetation, wildlife, aquatic biota, special status species, and their habitats) would be less during the operations and maintenance phase than for the exploration and drilling and construction phases because no new drilling or construction activities would take place. However, operations and maintenance activities have the potential to affect ecological resources mainly by reducing the acreage for foraging and migrating animals, fragmenting habitat, and creating noise at the project site during the life cycle of the project (which could last up to 50 years). Some of these impacts could be significant. Increased human activity also increases the risk of fire, especially in arid or semiarid areas. Applications of herbicides to control vegetation along access roads, buildings, and power plant structures, would increase the risk of wildlife exposure to contaminants.

Environmental Justice Possible environmental justice impacts during the operations and maintenance phase include the alteration of scenic quality in areas of traditional or cultural significance to minority populations. Noise, water, and health and safety impacts are also potential sources of disproportionate effects to minority or low-income populations.

Hazardous Materials and Waste Management Industrial wastes are generated during routine operations and maintenance activities (e.g., lubricating oils, hydraulic fluids, coolants, solvents, and cleaning agents). These wastes are typically placed in containers, characterized and labeled, possibly stored briefly, and transported by a licensed hauler to an appropriate permitted off-site disposal facility as a standard practice. Impacts could result if these wastes were not properly handled and were released to the environment. Environmental contamination could occur from accidental spills of herbicides or, more significantly, oil. Chemicals in open pits used to store wastes may pose a threat to wildlife and livestock.

Health and Safety Potential human health and safety impacts during the operations and maintenance phase would include exposures to geothermal fluids or steam during maintenance activities, system failures or well blowouts, and hazardous materials such as petroleum, oils, lubricants, and herbicides; and the risk of serious

injuries or accidents. Adverse impacts could also occur from the risk of electrical fires and wildfires caused by project activities; electric shock during transmission line and substation maintenance; and vehicular accidents due to increased traffic on local roads. The potential for such impacts can be minimized if appropriate safety procedures are implemented.

Land Use Impacts on land uses during the operations and maintenance phase are an extension of those that occurred during the exploration and drilling and construction phases. While, to some extent, land use can revert to its original uses (e.g., livestock grazing), many other uses (e.g., mining, farming, or hunting) would be precluded during the life span of the geothermal development. Mineral resources would remain available for recovery and operations and maintenance activities are unlikely to affect mining and energy development activities, military operations, livestock grazing, or aviation on surrounding lands.

Paleontological Resources The potential for impacts on paleontological resources would be limited primarily to unauthorized collection of fossils. This threat is present once the access roads are constructed, making remote areas more accessible to the public. Damage to localities caused by OHV use could also occur. The potential for indirect impacts (e.g., vandalism and unauthorized collection) would be greater during the production phase compared to the drilling/development phase, due to the longer duration of the production phase.

Socioeconomics Activities during the operations and maintenance phase would contribute to the local economy by providing employment opportunities, monies to local contractors, and recycled revenues through the local economy. The magnitude of these benefits would vary depending on the resource potential. Operations of a typical 50-MW power plant and related transmission lines would require an estimated 93 jobs and $8 million in income, but would vary depending on the community. Job availability would vary with different stages of construction. Expenditures for equipment, materials, fuel, lodging, food, and other needs would stimulate the local economy over the duration of the project, which could last up to 50 years. Economic impacts may occur if other land use activities (e.g., recreation, grazing, or hunting) are altered by geothermal development. Constructing facilities will alter the landscape and could affect the nonmarket values of the immediate area during the life of the geothermal development. Many of these land uses may be compatible; however, it's possible that some land uses will be displaced by geothermal development.

Soils and Geologic Resources Impacts to soils and geologic resources would be minimal during the operations and maintenance phase. The initial areas disturbed during the construction phase would continue to be used during standard operation and maintenance activities, but no additional impacts would occur unless new construction projects or drill sites are needed. Impacts associated with new construction projects or drill sites would be similar to those described for the exploration and drilling and construction phases.

Transportation Daily traffic levels, particularly heavy truck traffic, would be expected to be lower during the operations and maintenance phase compared to other phases of geothermal development. For the most part, heavy truck traffic would be limited to periodic monitoring and maintenance activities at the well pads and power plant.

Visual Resources Adverse impacts to visual resources would occur during the 10- to 30-year life of the geothermal development. Impacts during the operations and maintenance phase would result from the presence of facility structures and roads (where undeveloped land once stood), increased vehicular traffic to the site, and releases of steam plumes from the geothermal power plant. Periodic construction projects occurring throughout the life of the development would have impacts similar to those described for the construction phase.

Water Resources (Surface Water and Groundwater) Impacts to water resources during the operations and maintenance phase result mainly from the water demands associated with operating a geothermal power plant. Water resources during operations would be needed for replenishment of the geothermal reservoir through reinjection. However, because some water would be consumed by evaporation, additional water would need to be added to the system from another source. Makeup water to replace the evaporative losses and blowdown in a water-cooled power plant system would also be needed, depending on the type of power plant used (e.g., flash steam facilities can lose up to 20% of its cooling water due to evaporation, but binary plants are nonconsumptive because they use a closed-loop system). Water can also be lost due to pipeline failures or surface discharge for monitoring and testing the geothermal reservoir. The availability of water resources could be a limiting factor in siting or expanding a geothermal development at a given location. Cooling water or water from geothermal wells that is discharged to the ground or to an evaporation pond could affect the quality of shallow groundwater if allowed to percolate through the ground. However, the

potential for this type of impact is considered minor or negligible because the facility would have to comply with the of the discharge permit required by the state.

Geothermal Operations and Maintenance Relative to fossil fuel fired power generation, geothermal power plants are much less complex, being simple cycle, operate at relatively low pressure and temperature and have fewer auxiliaries. Nonetheless, geothermal plants incur a significant penalty with respect to the severe equipment operating environment created by saturated steam containing relatively high levels of impurities of non condensable gases, dissolved and suspended solids. Geothermal maintenance costs are about twice that of fossil fuel plant, due principally to the following problems which are characterisitic of the geothermal environment:

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Corrosion - of well casings, valves, surface pipelines (steam and condensate), structural steel, cooling tower components, building cladding and electrical switch gear

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Deposition - of geothermal mineral phases and corrosion products inside production and injection wells, steam field piping/ plant and steam turbines

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Erosion - of surface piping, valves and turbine blades

Sinclair Knight Merz has 20 years experience in the operation and maintenance of geothermal steamfields and power stations and promotes O&M practices based on:

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Highest possible steam quality through advanced separator design, sophisticated control of separator pressure and the use of secondary steam conditioning plant.

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Detailed attention to process requirements, material selection and plant equipment in power plant specification.

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Well defined and documented operational procedures.

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Training and technology transfer to ensure client organisation develops the required level of operational skills.

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Good preventative maintenance programs to minimize forced plant outages and to maximize turbine inservice periods, targeting at least 3 years operation between major maintenance shuts. This ensures high plant availability, which for a base load geothermal plant represents a high capacity (utilisation) factor, and high revenue.

Sinclair Knight Merz O&M services include:

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Drilling Engineering and Management – engineering of well workovers, redrills, cleanouts, and permeability enhancement through acidizing.

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Resource Management – through life assessment of reservoir performance, steam and injection reserves and resource problems.

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Steam Field Engineering – system re-engineering in response to changing production conditions, assessment and management of deposition problems (silica, calcite anhydrite, corrosion products), on line chemical tracer flow measurements.

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Steam Supply – steam quality measurement and improvement, contract steam flow metering, steam line corrosion problems, steam sales contracts.

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Turbines – performance testing, deposition problems.

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Condenser/ Cooling Circuit – optimization of thermodynamic performance and chemical dosing requirements through numerical modelling.

Steam turbines The steam turbine on a page about engines? Maybe you wondered about it. It is hardly used in means of transport, but the steam turbine has many things in common with the combustion engine. The steam turbine changes chemically stored energy into mechanical energy, too. It's called a heat-force engine. The steam turbine works similarly to the water turbine, which is known probably by everyone. Not water, but steam is used as working medium.

Turbine types When people began to use water power to win mechanical work, they looked first for the best forms of impellers. Three types were established thereby and variations of them are used today in various applications, among other in steam turbines in power stations, as marine propellers, as compressors in gas turbines etc. These three types are introduced here:

The pelton turbine The pelton turbine (also free-jet turbine) was invented 1880 by L.A. Pelton. It possesses spoon-shaped shovels, the jet hits the impeller tangentially, gets divided by the two shovels and transfers an impulse. The pelton turbine is used in storage power stations with downward gradients up to 2000 meters and can contain up to 6 nozzles.

Grafic: Pelton turbine enlarge (35 K, 770 * 905)

Grafic: Pelton turbine, source: http://wwwspof.gsfc.nasa.gov/stargaze/Spelton.htm

The francis turbine he reaction turbine invented by J.B. Francis 1849 is hit by the jet almost axially (toward the axle) and radially (away from the center). The rotor blades can be adjusted, in order to ensure an even run. It looks similar to the type shown below as Steam turbine.

The Kaplan turbine The Kaplan turbine, developed around 1915 by the Austrian V.Kaplan, looks like a marine propeller. The jet is led thereby axially on the freely adjustable shovel pages. Grafic: Kaplan turbine enlarge (35 K, 282 * 292)

Besides the types described above, there are still other types of water turbines, e.g. the Bànki turbine, which are not closer described here.

From the water- to the steam turbine The won realizations with water power let the researchers expect similar results with steam, too. Numerous engineers took part in the development of the steam turbine in the second half of the 19. Century. To mention are the Englishman Charles Parsons, the Swede Carl Gustav Laval and the American Charles Curtis, who made crucial contributions for the development of the steam turbine.

Diagram: 2-step steam turbine after Parsons (1883). This turbine possesses two impellers and an idler in the center. enlarge (154 K, 510 * 570), Image (18 K, 255 * 285), Mini steam turbine (For your website) (11 K, 100 * 112)

Mode of operation of the steam turbine Since it is a steam jet and no more a water jet who meets the turbine now, the laws of thermodynamics are to be observed now. The modern steam turbine is an action turbine (no reaction turbine), i.e. the steam jet meets from a being certain nozzle the freely turning impeller. There's a high pressure in front of the turbine, while behind it a low pressure is maintained, so there's a pressure gradient: Steam shoots

through the turbine to the rear end. It delivers kinetic energy to the impeller and cools down thereby: The pressure sinks. Steam is produced in a steam boiler, which is heated in power "Steam" stations by the burn of coal or gas or by atomic energy. Steam Steam turbines are operated today doesn't escape then, but after the age through the turbine it is of course no longer with normal condensed in a condensor and then pushed back into the steam water vapour only, but depending on boiler again by a pump. This has the advantage that for example the field of application also with in nuclear power stations work- and cooling water are clearly other materials, e.g. with freons). separated.

Multi-level steam turbines In modern steam turbines not only one impeller is propelled, but several being in a series. Between them idlers are situated, which don't turn. The gas changes its direction ing an idler, in order to perform optimally work again in the next impeller. Turbines with several impellers are called multi-level. The principle was developed 1883 by Parsons. As you know, with the cooling gas expands. Therefore it is to be paid attention when building steam turbines to a further problem: With the number of ed impellers also the volume increases, which leads to a larger diameter of the impellers. Because of that, multi-level turbines are always conical.

Coupling of several turbines

Grafic: Coupled steam turbine. source: Helmut Hütten, "Motoren", Motorbuchverlag Stuttgart, S.379

In power stations today, different types of turbines are used in a series, e.g. one high pressure -, two medium- and four low pressure turbines. This coupling leads to an excellent efficiency (over 40%), which is even better than the efficiency of large diesel engines. This characteristic and the relatively favorable production make the steam turbine competitionless in power stations. Coupled with a generator and fired by an atomic reactor, they produce enormously much electric current. The strongest steam turbines achieve today performances of more than 1000 megawatts.

A geothermal power plant uses its geothermal activity to generate power. This type of natural energy production is extremely environmentally friendly and used in many geothermal hot spots around the globe.

To harness the energy, deep holes are drilled into the earth (much like when drilling for oil) until a significant geothermal hot spot is found. When the heat source has been discovered, a pipe is attached deep down inside the hole which allows hot steam from deep within the earths crust to rise up to the surface. The pressurized steam is then channeled into a turbine which begins to turn under the large force of the steam. This turbine is linked to the generator and so the generator also begins to turn, generating electricity. We then pump cold water down a new pipe which is heated by the earth and then sent back up the first pipe to repeat the process. The main problems with geothermal energy is that firstly, you must not pump too much cold water into the earth, as this could could cool the rocks too much, resulting in your geothermal heat source cooling down. secondly, geothermal power plants must be careful of escaping gases from deep within the earth. We suggest if you would like to learn more on this topic, you take a look at our advantages of geothermal energy, and our disadvantages of geothermal energy articles.

A very good way of thinking about geothermal energy is ing that all our continents lie on molten rock deep within the earth, this rock produces tremendous levels of heat that we are able to extract, just think of your nation lying on a bed of fire. Geothermal power is one of the most renewable energy sources that exists on our planet today, the earth will contain this heat for our lifetime. If this heat disappears, our planet will become too cold to survive on. You can purchase small scale geothermal equipment for your home yet this works in a different manner to geothermal power stations. The power stations extract the heat directly from deep within the earth, whereas home geothermal hot water equipment absorbs heat over a lengthy period of time from a few meters beneath your feet. http://www.clean-energy-ideas.com/geothermal_power.html

The ground beneath our feet contains a significant amount of energy in the form of heat. All of this geothermal energy has the potential to generate geothermal power to provide large amounts of electricity. People have used geothermal energy in the form of hot springs for centuries, however, the first attempt to generate electricity from this energy source did not occur until the 20th century.

The production of electricity from geothermal energy sources can be a highly efficient method to generate a source of clean and renewable energy. Location is key for the development of an efficient geothermal power station, and therefore, significant levels of electricity can only be generated in certain areas. There are only a handful of locations across the world that are capable of producing viable and efficient levels of electricity from geothermal energy sources. As a result of this, in 2007, less than 1% of the worlds electricity supply was produced from geothermal sources. To harness geothermal energy and transform this into electricity, geothermal power stations are designed in a variety of ways. The three main power plant designs which utilise geothermal as an energy source are; "dry steam", "flash steam", and "binary-cycle" power stations.

Geothermal Ground Source Heat Pumps Alternative "geothermal energy systems" are available, yet instead of providing power, they focus on providing heat and warmth. This heat can be used to heat water for your home or to simply provide heating for your house.

Geothermal energy systems utilising ground source heat pumps are different to geothermal power systems. The main difference is that ground source heat pump systems only make use of the first few meters of ground.

Water is usually pumped through one end of a lengthy piping system and by the time it reaches the other end, the water is of a higher temperature than it was at the start. This allows for an energy efficient boiler system as it doesn't have to boil water from cold. The great advantage of geothermal ground source heat pumps is that they can be used in many locations. Even cold regions such as Norway and Sweden see efficient results when using ground source heat pumps. A geothermal heat pump system can be very efficient in providing your home with a source of lower cost hot water. The use of a ground source heat pump with a backup boiler allows your boiler to use less energy to heat the water than it would have previously. This can save you significant amounts of money on energy bills for your home or business.

Geothermal Disadvantages Here are some disadvantages of using the power of geothermal energy to provide heat for your home or water through the use of a ground source heat pump. The initial cost of design and installation can be costly yet this investment would be likely to pay off over the years of operation. The area needed to lay the piping system can be quite large and this may not be suitable for small developments. These are just some of the disadvantages of using geothermal energy yet there are many more advantages which greatly outweigh these negatives.

Geothermal System Suppliers If you're looking for suppliers or installers of geothermal energy systems, then our geothermal suppliers area may be of interest to you and could help you locate a reputable supplier in your area.

Guide to Power Plant Preventive Maintenance Power plant preventive maintenance refers to set of planned activities -- which include nondestructive testing and periodic inspection as well as maintenance -- designed to prolong the life of equipment and facilities. It may include adjustment, cleaning, lubrication and replacement of minor components.

1. Benefits o

Preventive maintenance activities can be classified as periodic, or time-based, planned or predictive. Their aim is to reduce the amount of unplanned maintenance work -- which consumes a large proportion of the cost of generating electricity -- needed in a power station.

Boilers o

There are various conventional preventive maintenance techniques associated with boilers and boiler materials in power plants. These include liquid penetrant, magnetic particle and ultrasonic testing inspection techniques.

Turbines o

Gas turbines, which use high temperature combustion gases as a working fluid, place severe thermal stresses on their components, so they need to be inspected and repaired or replaced on a regular basis. Even low temperature steam turbines can suffer from fatigue cracking or stress corrosion cracking and need to be repaired or reconditioned in similar fashion

Read more: Guide to Power Plant Preventive Maintenance | eHow.com http://www.ehow.com/facts_7857785_guide-power-plant-preventivemaintenance.html#ixzz1bE5PRTFY Related Searches:  

Biomass Plant Geothermal Heating System

Parts of a Geothermal Power Plant

Geothermal plants use the Earth's natural heat to generate electricity. According to the Energy Information istration, the United States in 2009 generated 15 billion kilowatt-hours of power using geothermal power plants. Geothermal power uses the heat of the Earth's core to generate usable electricity. Because the Earth has substantially more heat energy than can be used or extracted by geothermal plants, scientists consider geothermal power sustainable, like wind or solar power. Like most power plants, from wind turbines to nuclear power plants, geothermal plants ultimately generate electricity by turning a turbine whose motion generates usable electricity.

1. Geothermal Vents o

The geothermal vent is the first component of a geothermal plant. A geothermal vent is a deep well drilled into the Earth that the power plant uses to tap into the Earth's heat. A geothermal plant may have two goals for its vent; most current geothermal plants draw superheated, pressurized water upward; these are called flash steam plants. Geothermal plants may also simply dig far enough underground, as many as three kilometers, to reach a point where the Earth is warm enough to boil water, these are called dry steam vents.

Steam Generator o

Another key component of a geothermal plant is the steam production unit, which can take multiple forms. In a flash steam vent, superheated pressurized water is drawn from its place underground to low-pressure tanks. The pressure of the Earth kept the water in liquid form despite its high temperature, and by removing that pressure the hot water instantly turns to steam, hence the term flash steam. In a dry steam plant, the plant technicians pump water to the bottom of the vent where the Earth's heat boils the water and turns it into steam.

Turbine o

Regardless of the plant type, both flash steam and dry steam plants pump the steam from the geothermal vent to a large turbine. The steam es this turbine, turning it in the process. This turbine is attached to an electric generator, and as the turbine turns the generator turns the mechanical energy into electric energy, thus converting the heat from the Earth into usable electricity.

Condenser o

After the steam es through the turbine, it continues to a condenser chamber. This chamber condenses the steam back into liquid water by cooling it. The excess heat lost as the steam turns to liquid water may be used for other applications, such as heating or greenhouse farming. The cooled liquid water is then typically pumped back into the ground to either restart the boiling process for dry steam or to replenish the natural heated aquifer for flash steam plants.

Read more: Parts of a Geothermal Power Plant | eHow.com http://www.ehow.com/info_8621582_parts-geothermal-power-plant.html#ixzz1bE8Xs9t9

What Are the Advantages of Geothermal? By Marty Simmons, eHow Contributor updated December 07, 2010

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Power Generation Closed Loop Geothermal

1.

o

A geothermal source

Geothermal power is one of the few renewable energy sources available. Coming in several forms, from full-scale electrical power plants to a simple pump to help save on your home

energy bills, geothermal power is used all over the world. Geothermal plants supply more than 10,000 megawatts of electricity to 24 countries, according to the Geothermal Energy Association. Low pollution and other advantages make geothermal power a popular choice for green energy advocates.

2. Low Maintenance o

Both geothermal power plants and home heat pumps have low lifetime costs, since most of the equipment is underground and there are few moving parts. Most of any geothermal system is made up of pipes that transfer water from a heat source to power a turbine. Other than on the turbines, the wear and tear is minimal.

Low Pollution o

Power plants using geothermal heat sources have zero emissions, compared with fossil fuel plants. No burning takes place during geothermal energy production and only steam is produced to power generators. Although small amounts of sulfides and other gases associated with volcanic activity may be released, they are at much lower levels, compared with traditional fossil fuels, and these emissions are easily mitigated by filtering systems.

Near Infinite Fuel Source o

Areas with volcanic activity or warmer crust near the Earth's surface are constantly having their heat replenished at a rate much faster than can be exploited by geothermal power plants. As a result, they can practically never run out of fuel. The continuous decay of radioactive elements in the Earth's crust will continue to provide heat longer than fossil fuels.

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References

Read more: What Are the Advantages of Geothermal? | eHow.com http://www.ehow.com/list_7615461_advantages-geothermal.html#ixzz1bE9eyBs9