6.10 Geothermal Energy

• What is the primary source of geothermal energy?

  Earth's internal heat
• In a geothermal power plant, hot steam from underground reservoirs is piped to a turbine
• In a geothermal power plant, the steam is condensed back into water and returned to the reservoir.
• What type of system uses stable underground temperatures to heat and cool buildings?

  Ground-source heat pumps
• A key advantage of geothermal energy is that it is constantly replenished by the Earth's internal heat
• Geothermal energy is only available in specific locations with geothermal hotspots.
• What are the two primary sources of the Earth's internal heat that contribute to geothermal energy?

  Planetary formation and radioactive decay
• Radioactive decay releases energy as heat when unstable elements in the Earth's crust and mantle decay
• In a geothermal power plant, the mechanical energy from the turbine drives an electricity generator.
• Why is condensed water reinjected into the geothermal reservoir after cooling?

  To maintain reservoir pressure
• While fossil fuels are reliable and produce high energy output, they are non-renewable
• What is returned to the geothermal reservoir to maintain pressure and sustainability?

  Condensed water
• The reinjection of condensed water into the geothermal reservoir helps prevent ground subsidence.
• The equation $E =$$mc^{2}$ describes the relationship between energy and mass
• Match the energy source with its key characteristic:

  Geothermal ↔️ Low emissions

  Solar ↔️ Intermittent

  Fossil Fuels ↔️ High energy output
• Steps in the operation of a geothermal power plant

  1️⃣ Extraction of hot water or steam

  2️⃣ Turbine operation

  3️⃣ Cooling and condensation

  4️⃣ Reinjection into the reservoir
• The temperature of water or steam extracted from geothermal reservoirs can range from 150°C to 370°C
• The mechanical energy from the turbine in a geothermal power plant drives an electricity generator.
• What are two methods used to cool steam after it exits the turbine in a geothermal power plant?

  Cooling towers or condensers
• Condensed water reinjected into the geothermal reservoir helps maintain reservoir pressure
• What makes geothermal energy sustainable?

  Minimal environmental impact
• Geothermal energy's low emission rates make it a key resource in transitioning to sustainable energy.
• Geothermal energy is heat derived from the Earth's internal heat
• Match the source of geothermal energy with its description:

  Planetary Formation ↔️ Heat from Earth's accretion

  Radioactive Decay ↔️ Heat released by unstable isotopes
• Geothermal energy originates from planetary formation and radioactive decay
• Order the steps in the formation of geothermal energy from planetary formation:

  1️⃣ Initial heat from Earth's formation

  2️⃣ Kinetic energy conversion to thermal energy

  3️⃣ Compaction and friction during formation
• Uranium-238 is a key isotope involved in radioactive decay that contributes to geothermal energy.
• What range of temperatures is typically found in underground geothermal reservoirs?

  150°C to 370°C
• Thermal energy is converted to mechanical energy as the turbine blades rotate
• Steps in cooling and condensing steam in a geothermal power plant:

  1️⃣ Steam exits the turbine

  2️⃣ Cooling towers or condensers cool the steam

  3️⃣ Steam condenses into water
• The reinjection of condensed water into the geothermal reservoir helps maintain reservoir pressure and prevents ground subsidence.
• Geothermal energy is considered a renewable source because it is constantly replenished by the Earth's internal heat
• What are two characteristics that make geothermal energy reliable compared to solar or wind energy?

  Weather-independent, low emissions
• What are the four advantages of geothermal energy outlined in the study material?

  Renewable, sustainable, low emissions, reliable
• Geothermal energy is constantly replenished by the Earth's internal heat
• What does sustainability in geothermal energy mean?

  Minimal environmental impact if managed properly
• Geothermal energy produces significantly less greenhouse gases than fossil fuels
• Geothermal energy is continuously available regardless of weather conditions
• Geothermal energy is weather-dependent like solar and wind energy

  False
• Match the advantage of geothermal energy with its corresponding disadvantage:

  Renewable ↔️ Location-specific availability

  Sustainable ↔️ High initial costs

  Low emissions ↔️ Potential land subsidence

  Reliable ↔️ Possible air pollutants