How can Earth's internal heat be used to make electricity and warm buildings?
Topic 6.10 Geothermal Energy: describe how geothermal energy is captured and evaluate its benefits and drawbacks.
A focused answer to APES Topic 6.10, covering how geothermal energy from Earth's internal heat is used for electricity and heating, ground-source heat pumps, the benefits (renewable, reliable, low emissions) and drawbacks (location, cost, gas release), and a worked geothermal heating calculation.
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What this topic is asking
The College Board (Topic 6.10) wants you to describe how geothermal energy is captured and evaluate its benefits and drawbacks.
How geothermal energy works
Benefits
Drawbacks
Why this matters
Geothermal ties Unit 6 back to plate tectonics (Unit 4): the same boundaries that cause earthquakes and volcanoes provide accessible heat. As a reliable, low-carbon renewable, it complements intermittent solar and wind, so the AP exam uses it to test whether you can match an energy source to its geographic and geological constraints.
Try this
Q1. Identify the source of geothermal energy. [1 point]
- Cue. Heat from Earth's interior (from radioactive decay and residual formation heat).
Q2. Explain why geothermal power is not equally available everywhere. [2 points]
- Cue. High-grade geothermal heat reaches the surface mainly near tectonic plate boundaries and volcanic regions, so places far from plate boundaries have heat too deep to tap economically.
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2022 (style)4 marksSection II (FRQ). (a) Describe the source of geothermal energy. (b) Explain how a geothermal power plant generates electricity. (c) Identify one reason geothermal energy is not equally available everywhere. (d) Identify one environmental drawback of geothermal energy.Show worked answer →
A 4-point FRQ on geothermal energy.
(a) Describe (1 point): geothermal energy is heat from Earth's interior, produced by radioactive decay and residual formation heat, reaching the surface most strongly near plate boundaries.
(b) Explain (1 point): the heat boils water (or uses naturally hot water or steam) to produce steam that spins a turbine connected to a generator, producing electricity.
(c) Identify (1 point): geothermal is concentrated near tectonic plate boundaries and volcanic regions, so high-grade resources are not available everywhere.
(d) Identify (1 point): any one of releasing dissolved gases such as hydrogen sulfide, depleting a local reservoir if overused, land subsidence, or high drilling cost.
Markers reward Earth's internal heat as the source, the steam-turbine-generator mechanism, the plate-boundary location limit, and a valid drawback.
AP 2019 (style)1 marksSection I (multiple choice). Geothermal energy is most readily available in regions that are: (A) far from any plate boundary (B) near tectonic plate boundaries and volcanic activity (C) at high latitudes only (D) in deep ocean basins only. Justify your choice.Show worked answer →
A 1-point MCQ on geothermal location. The answer is (B).
Geothermal heat reaches the surface most strongly near tectonic plate boundaries and volcanic regions, where hot rock and magma are close to the surface. Areas far from plate boundaries (A) have heat too deep to tap cheaply; latitude (C) and ocean basins (D) do not determine geothermal availability. The trap is forgetting that geology, specifically proximity to plate boundaries, controls where high-grade geothermal energy is found.
Related dot points
- Topic 6.1 Renewable and Nonrenewable Resources: distinguish renewable from nonrenewable energy resources and explain why the distinction matters for sustainability.
A focused answer to APES Topic 6.1, covering the difference between renewable and nonrenewable energy resources, examples of each, the idea of potentially renewable resources, and why the distinction matters for sustainability, with a worked depletion calculation.
- Topic 4.1 Plate Tectonics: explain how convection in the mantle drives plate movement and describe the three types of plate boundary and their landforms and hazards.
A focused answer to APES Topic 4.1, covering mantle convection, the three plate boundary types (divergent, convergent, transform), the landforms and hazards each produces, hot spots, and the link to natural resources, with a worked boundary-identification question.
- Topic 6.4 Distribution of Natural Energy Resources: explain why energy resources are unevenly distributed and the consequences of that uneven distribution.
A focused answer to APES Topic 6.4, covering why fossil fuels and renewable resources are unevenly distributed across the globe, how geology and geography determine availability, and the economic and political consequences of that uneven distribution, with a worked import dependence calculation.
- Topic 6.8 Solar Energy: describe how solar energy is captured using photovoltaic, active and passive systems and evaluate its benefits and drawbacks.
A focused answer to APES Topic 6.8, covering photovoltaic cells, active and passive solar heating, the benefits (renewable, low emissions) and drawbacks (intermittency, land, cost) of solar energy, and a worked photovoltaic output calculation.
- Topic 6.13 Energy Conservation: describe strategies for energy conservation and efficiency and explain how they reduce environmental impact.
A focused answer to APES Topic 6.13, covering energy conservation and efficiency strategies (efficient vehicles, appliances, lighting, insulation, public transport, CAFE standards), the difference between conservation and efficiency, and how they reduce impact, with a worked energy-saving calculation.
Sources & how we know this
- AP Environmental Science Course and Exam Description — College Board (2020)