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Questions and Answers
What is the definition of Geothermal Energy?
What is the definition of Geothermal Energy?
It is the energy stored in the form of heat beneath the surface of the solid Earth.
What scientific organization defines geothermal energy in Germany?
What scientific organization defines geothermal energy in Germany?
VDI 4640
Where does the majority of the Earth's heat flow come from?
Where does the majority of the Earth's heat flow come from?
Match the following geological features with their descriptions:
Match the following geological features with their descriptions:
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The Earth is warming up due to radiogenic heat.
The Earth is warming up due to radiogenic heat.
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What is the average geothermal gradient up to depths that can be reached with drilling technologies?
What is the average geothermal gradient up to depths that can be reached with drilling technologies?
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The geothermal gradient is always uniform throughout the Earth.
The geothermal gradient is always uniform throughout the Earth.
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What are the two main parts of the Earth's lithosphere?
What are the two main parts of the Earth's lithosphere?
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What is the thickness of the lithosphere in oceanic zones?
What is the thickness of the lithosphere in oceanic zones?
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What is the thickness of the lithosphere in continental zones?
What is the thickness of the lithosphere in continental zones?
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The lithosphere behaves as a rigid body.
The lithosphere behaves as a rigid body.
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What is the thickness of the asthenosphere?
What is the thickness of the asthenosphere?
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The asthenosphere exhibits a more plastic behavior than the lithosphere.
The asthenosphere exhibits a more plastic behavior than the lithosphere.
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What is the name of the geological phenomenon that plays a key role in plate tectonics?
What is the name of the geological phenomenon that plays a key role in plate tectonics?
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What is the primary cause of subduction?
What is the primary cause of subduction?
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Subduction only occurs along the converging edges of plates.
Subduction only occurs along the converging edges of plates.
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Which of the following best describes the process of subduction?
Which of the following best describes the process of subduction?
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Subduction results in the destruction of oceanic crust.
Subduction results in the destruction of oceanic crust.
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Subduction leads to the creation of new oceanic crust at mid-ocean ridges.
Subduction leads to the creation of new oceanic crust at mid-ocean ridges.
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What are the three main types of plate tectonic processes?
What are the three main types of plate tectonic processes?
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The most important geothermal areas are located at the edge of the plates.
The most important geothermal areas are located at the edge of the plates.
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What are the three key components of a geothermal system?
What are the three key components of a geothermal system?
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What is the primary heat source for most geothermal systems?
What is the primary heat source for most geothermal systems?
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What type of rock typically serves as a reservoir for geothermal fluids?
What type of rock typically serves as a reservoir for geothermal fluids?
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Geothermal fluids are always composed of hot water.
Geothermal fluids are always composed of hot water.
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What are the three main types of direct-use geothermal applications?
What are the three main types of direct-use geothermal applications?
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The use of geothermal heat pumps is the most widespread geothermal application worldwide.
The use of geothermal heat pumps is the most widespread geothermal application worldwide.
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What is the primary method of utilizing high-temperature geothermal resources?
What is the primary method of utilizing high-temperature geothermal resources?
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Medium-to-low temperature geothermal resources are only suitable for space heating.
Medium-to-low temperature geothermal resources are only suitable for space heating.
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What is the name of the diagram that illustrates the possible uses of geothermal fluids at different temperatures?
What is the name of the diagram that illustrates the possible uses of geothermal fluids at different temperatures?
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Which of the following is NOT a common application of Geothermal Energy?
Which of the following is NOT a common application of Geothermal Energy?
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What is the name of the process where high-pressure water is injected into hot, dry rock to create a reservoir for extracting geothermal energy?
What is the name of the process where high-pressure water is injected into hot, dry rock to create a reservoir for extracting geothermal energy?
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What type of geothermal power plant utilizes a working fluid to transfer heat from a geothermal source to a turbine?
What type of geothermal power plant utilizes a working fluid to transfer heat from a geothermal source to a turbine?
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Dry steam power plants are the most common type of geothermal power plant.
Dry steam power plants are the most common type of geothermal power plant.
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Flash steam power plants are more efficient than dry steam power plants.
Flash steam power plants are more efficient than dry steam power plants.
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Binary cycle power plants are more efficient than flash steam power plants for medium-to-low temperature geothermal resources.
Binary cycle power plants are more efficient than flash steam power plants for medium-to-low temperature geothermal resources.
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What is the purpose of a cooling tower in a geothermal power plant?
What is the purpose of a cooling tower in a geothermal power plant?
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How does a cooling tower work?
How does a cooling tower work?
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The wet bulb temperature is the limiting temperature for a condenser exchanging heat with external air in a geothermal power plant.
The wet bulb temperature is the limiting temperature for a condenser exchanging heat with external air in a geothermal power plant.
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Why is the use of organic fluids in geothermal power plants advantageous?
Why is the use of organic fluids in geothermal power plants advantageous?
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Organic fluids are always more efficient than water in all power applications.
Organic fluids are always more efficient than water in all power applications.
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What is the name of the type of geothermal technology that uses a closed-loop binary cycle system to generate electricity?
What is the name of the type of geothermal technology that uses a closed-loop binary cycle system to generate electricity?
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ORC systems are particularly well suited for using geothermal resources to generate electricity.
ORC systems are particularly well suited for using geothermal resources to generate electricity.
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ORC power plants are particularly efficient for producing electricity at high power output levels (like > 10 MW).
ORC power plants are particularly efficient for producing electricity at high power output levels (like > 10 MW).
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The expansion ratio for a single expansion stage in a turbine increases with the molecular mass of the working fluid.
The expansion ratio for a single expansion stage in a turbine increases with the molecular mass of the working fluid.
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The use of a high molar mass working fluid in an ORC system results in higher tip speed for the turbine.
The use of a high molar mass working fluid in an ORC system results in higher tip speed for the turbine.
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What is the name of the geothermal test site located in France?
What is the name of the geothermal test site located in France?
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What is the name of the geological feature where the Soultz-sous-Forêts geothermal test site is located?
What is the name of the geological feature where the Soultz-sous-Forêts geothermal test site is located?
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The Soultz-sous-Forêts geothermal test site is the first HDR power plant in the world to generate electricity.
The Soultz-sous-Forêts geothermal test site is the first HDR power plant in the world to generate electricity.
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What is the main advantage of HDR (Hot Dry Rock) technology?
What is the main advantage of HDR (Hot Dry Rock) technology?
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The use of ORC technology is particularly well suited for thermal applications such as district heating and greenhouse heating.
The use of ORC technology is particularly well suited for thermal applications such as district heating and greenhouse heating.
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What is the name of the city in Iceland that utilizes geothermal energy for district heating?
What is the name of the city in Iceland that utilizes geothermal energy for district heating?
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Geothermal energy is not a viable option for providing heating and cooling for residential buildings.
Geothermal energy is not a viable option for providing heating and cooling for residential buildings.
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What is the name of the refrigeration cycle that uses a mixture of ammonia and water to operate at lower temperatures than traditional vapor-compression refrigeration cycles?
What is the name of the refrigeration cycle that uses a mixture of ammonia and water to operate at lower temperatures than traditional vapor-compression refrigeration cycles?
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Study Notes
Renewable Energy Technologies - Geothermal Energy
- Geothermal energy is energy stored as heat beneath the Earth's surface.
- A guideline in Germany (VDI 4640) defines geothermal energy as heat beneath the Earth's solid surface.
- The Earth's internal heat flow is approximately 42 x 1012 W.
- 19% of this heat originates from the crust (though representing only 2% of the volume).
- 77% comes from the mantle (representing 82% of the Earth's volume).
- 4% comes from the core (though representing 16% of the volume).
- The core does not contain radioactive isotopes.
- The Earth is cooling down but the process is very slow (300°C decrease at the mantle over 3 billion years).
Geothermal Energy - Temperatures in the Earth
- Temperatures increase with depth into the Earth.
- At a depth of 2,000 kilometers, the temperature reaches 4,000° Celsius.
- At a depth of 6,000 kilometers, the estimated temperature is significantly higher, around 5,000–6,000° Celsius.
Energy Balance (Stacey and Loper, 1988)
- About half of the total heat flow originates from radioactive decay. Data shows the figures mentioned in one of the previous sections.
Power Generation - Installed Geothermal Generating Capacities (1995-2000)
- Table 1 details installed global geothermal power capacity from 1995 to 2000, plus data for the end of 2003.
- Figures are in MW
- Countries with high installed capacity presented in the document include Argentina, China, Costa Rica, Indonesia, Iceland, Italy, Japan, Mexico, New Zealand, Philippines, and USA.
Geothermal Energy Capacity Worldwide (2009-2023)
- A graph shows global geothermal capacity growth from 2009 to 2023, measured in megawatts.
- Leading countries, including the U.S., Indonesia, and the Philippines, are highlighted.
Larderello – Early Days of the Boric Acid Industry
- In the early 1800s, a factory in Larderello extracted boric acid from naturally occurring hot water.
- Francesco Larderel, a founder of this industry, developed a system relying on the heat of the boric fluids for the evaporation process instead of rapidly depleting forests.
Mechanical Energy of Natural Steam at Larderello
- In the late 19th century, natural steam was used to power primitive gas lifts, reciprocating pumps, and other equipment in drilling wells, and more broadly in the boric acid industry.
- A machine for power generation from geothermal energy was invented in Larderello in 1904.
Non-Electric Applications
- A graph displays the installed direct-use geothermal capacity and annual utilization from 1995 to 2020.
- A table details worldwide direct-use geothermal capacity and annual utilization (2019) for various regions like Africa, Americas.
Geothermal Gradient
- The average geothermal gradient is roughly 2.5–3°C per 100 meters until a depth of 10,000m.
- Data in the article indicates that 50–60° Celsius is found at 2,000 meters of depth.
- Geothermal gradients vary widely across different geological locations.
- The average Earth's heat flow is noted with specific values for continents and oceans respectively.
Plate Tectonic Processes
- Convective movements in the asthenosphere are driven by heat.
- The decay of radioactive elements generates immense heat within the Earth's deep hotter zones.
- Dense and heavy rocks sink; less dense and lighter rocks rise, creating a convection pattern.
Subduction
- Subduction is a process where a tectonic plate slides beneath another.
- This process plays a key role in geological and plate tectonic theories.
- The process occurs along converging plate boundaries where the oceanic crust is destroyed.
Types of Geothermal System - Components
- A geothermal system includes a heat source, reservoir, and fluid.
- Cap rock effectively prevents and reduces thermal conduction.
- Reservoirs act as heat exchangers where the thermal convection occurs.
- Hot water and steam emerge from hot springs or steam vents.
Geothermal Resources - Classification
- Geothermal resources are classified based on temperature: low, intermediate, and high enthalpy.
- This classification is based on temperatures in degrees Celsius.
Use of Geothermal Resources
- Electricity generation is one of the most crucial applications for high-temperature geothermal resources (above 150°C).
- Medium to low-temperature geothermal resources are adapted to various applications.
- A diagram, the Lindal diagram (1973), showcases how geothermal fluids can be utilized across a broad range of temperatures for various applications.
Thermal Applications
- A diagram illustrates various utilization options including district heating in Reykjavik.
- District heating in Reykjavik, Iceland, uses geothermal energy for heating homes and buildings.
- Specific numerical data for the geothermal fields and district heating use cases are presented.
Greenhouse Heating
- A graph presents the optimum growth rates for different plants under varying temperature input/output levels.
Aquaculture and Food Animals
- The graph shows the relationship between temperature and growth for various livestock.
- It illustrates how growing conditions (temperature) impact the output of animal farming.
ORC Cycle
- Data on the ORC cycle includes the operation of generating electricity efficiently and the conditions of application and use cases.
Specific ORC Components
- Different diagrams illustrate parts and components of the ORC system.
- Components like Turbines, Condensers, Pump are illustrated and described for different ORC technologies.
Comparison of Water and Organic Fluids in ORC Cycles
- Comparisons are made between the use of water and organic fluids in ORC cycle turbines to identify advantages and disadvantages in applications (size, pressure, enthalpy).
Cooling Tower Use
- Describes the reasons for using cooling towers rather than condensers in geothermal power generation.
- Explains why wet-bulb temperatures are more crucial for evaluating geothermal cooling systems.
Geothermal Applications
- Data is presented in various sections about the European test site in Soultz, including the specific milestones and details.
Other Information
- Extensive data on the ORC cycle are laid out, including various diagrams associated with the different types of ORC technology (different types of ORC and possible applications). Additional useful details about the application of ORC, such as the power plant in Soultz, are presented.
- Detailed maps exhibiting temperature distribution as a function of depth (in various layers) and geographic locations in Europe are discussed. The maps help highlight the geothermal resource distribution and relevant data.
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Description
Explore the fascinating world of geothermal energy, the heat stored beneath the Earth's surface. Learn about its sources, temperature variations at different depths, and the potential of this renewable energy technology. This quiz will challenge your understanding of geothermal dynamics and its significance in today's energy landscape.
