12.5

• Geothermal energy is the internal heat of the earth.
• Geothermal gradient is the rate of temperature increase for unit depth.
• Geothermal system is a confined area where groundwater transfers heat from a source to a heat sink and is the basis for energy exploitation.
• Heat source takes the form of a shadow magmatic intrusion or naturally high geothermal gradients / naturally occurring .
• Geothermal fluid refers to groundwater heated (sometimes superheated) by the source and is often highly mineralized.
• Geothermal fluid is the vessel of heat and is what power plants extract to power turbines, fluids may be augmented artificially using injection wells.
• Reservoir is a volume of permeable rock which starts geothermal fluid and can be exploited at a profit.
• Reservoir, artificial reservoirs may be created with hydraulics fracturing .
• Geothermal power plants are used in order to generate electricity by the use of geothermal energy or the earth's internal thermal energy.
• Geothermal vent is a deep well drilled into the earth that the power plant uses to tap into the earth's heat the vent usually from 150-400 feet deep.
• Steam generator is used for covering hot water into steam at high pressure and often with supplementary coils to superheat the steam the very hot steam then makes the turbines spin fast.
• Turbine is a machine with at least one moving part with blades attached, moving fluid acts on the blades so that they create move and create rotational energy which will converted to ME then to EE.
• Condenser cools and condenses the steam back into liquid water by cooling it, the liquid is then pumped back into the earth's underground for recycling.
• Mechanism of geothermal power plant - water is heated and then sent through a steam turbine where the thermal energy is converted to electricity with a generator through a phenomenon called electromagnetic induction.
• Dry steam plant uses steam directly from a geothermal reservoir to turn generator turbines.
• Binary circle power plant transfers the heat from geothermal hot water to another liquid that turns to steam which is used to drive a generator turbine.
• Philippines is the third largest producer or geothermal power in the world behind the USA providing 12.2% of the country's electricity.
• The first geothermal plant in the Philippines was built in barrio cale in tiwi, albay 1967.
• There are 7 producing geothermal fields around the country.
• Impact of geothermal power plants - geothermal fluids are pollutants, containing dissolved metals and ions and having higher temperatures, Improper handling may contaminate water tables of surface waters + these fluids contain greenhouse gases such as carbon dioxide and hydrogen sulfide among others.
• Power plants require large areas of cleared land for pipelines and drilling rigs, careless extraction can empty a reservoir.
• Subsidence or sinking of the surface above the reservoir can happen when removing the fuel.
• Over extraction and hydraulic fracturing can generate earthquakes in the vicinity.