AP Environmental Science, AP exams, 10–15%

Unit 6: Energy Resources and Consumption

Unit 6 surveys energy sources from fossil fuels through nuclear and the renewables, comparing them on availability, cost, emissions, and land or water impact. Global consumption patterns and the uneven distribution of resources frame the comparison. Energy-unit calculations are common on the calculation free-response question.

Position: 6 of 9 units
Published weighting: 10–15% in the official framework
Topics covered: 6 topics in this guide

What is covered

Topics inside this unit.

These topics describe the scope students most often review for this part of AP Environmental Science. Treat them as a study checklist rather than an exhaustive list of what a single exam form can sample.

Renewable and nonrenewable resources: How resources are classified, and what distinguishes a renewable source from a sustainable practice.
Global energy consumption and distribution: Consumption patterns across countries and the geographic unevenness of energy resources.
Fossil fuels: Coal, oil, and natural gas formation, extraction methods, and their comparative emissions profiles.
Nuclear power: Fission, reactor components, the waste problem, and the trade-off between low emissions and accident risk.
Solar, wind, hydro, and geothermal energy: How each converts a natural flow into electricity, and the siting and intermittency constraints on each.
Biomass, hydrogen fuel cells, and conservation: Biomass and biofuel trade-offs, fuel cell chemistry, and the efficiency measures that reduce demand.

Study tips

How to practice Energy Resources.

Section-specific guidance that follows from how this material is usually tested.

Practice energy conversions between kilowatt-hours, joules, and barrels with the units written on every step.
Keep one advantage and one disadvantage per energy source on a single card set for fast comparison questions.
Rehearse a full calculation free-response answer, including showing the setup, since setup earns points even if arithmetic slips.

Where this fits

Unit 6: Energy Resources and Consumption is 6 of 9 units in the AP Environmental Science guide, and it carries a published weighting of 10–15% in the official framework. Use the full guide to balance it against everything else you have to review.

Back to the AP Environmental Science guide Official exam information

Sample Energy Resources questions

Practice questions, not yet expert-reviewed

Original practice questions written to the published framework for this section. No expert has reviewed them, and they are not taken from any official exam. Try each one before you open the answer.

Question 1Foundational
Which fossil fuel releases the least carbon dioxide per unit of energy produced when it is burned?
1. ACoal
2. BCrude oil
3. CNatural gas
4. DPeat
Show answer
Answer: C. Natural gas
Natural gas is mostly methane, which has four hydrogen atoms for every carbon atom, so a large share of its energy comes from forming water rather than carbon dioxide. Coal is the tempting distractor for anyone thinking only about abundance, but coal is nearly pure carbon and emits the most carbon dioxide per unit of energy. Lower carbon dioxide does not make natural gas clean overall, since extraction leaks methane, itself a potent greenhouse gas.
Key insight: The higher the hydrogen-to-carbon ratio of a fuel, the less carbon dioxide per unit of energy released.
Question 2Foundational
Which renewable energy source generates electricity using heat that comes from inside the Earth?
1. AHydroelectric
2. BGeothermal
3. CSolar thermal
4. DBiomass
Show answer
Answer: B. Geothermal
Geothermal plants tap steam or hot water heated by the Earth's interior to spin a turbine, which is why they are concentrated near plate boundaries and volcanic regions. Solar thermal is the tempting distractor because it also makes electricity from heat, but that heat comes from concentrated sunlight rather than from the crust. Geothermal output does not vary with weather or time of day, so it can serve as baseload power.
Key insight: Geothermal is site-limited but steady, which is an unusual combination among renewables.
Question 3Intermediate
What is the function of the control rods in a nuclear fission reactor?
1. AThey slow down neutrons so that fission is more likely
2. BThey carry heat from the core to the steam generator
3. CThey shield workers from gamma radiation
4. DThey absorb neutrons to slow or stop the chain reaction
Show answer
Answer: D. They absorb neutrons to slow or stop the chain reaction
Control rods are made of neutron-absorbing materials such as boron or cadmium, so lowering them into the core removes neutrons and slows fission, and fully inserting them shuts the reactor down. The tempting distractor describes the moderator, usually water or graphite, which slows neutrons so uranium-235 can capture them more readily. The coolant is the separate loop that carries heat away from the core.
Key insight: The moderator slows neutrons to keep fission going; control rods absorb them to hold it in check.
Question 4Intermediate
A 100-watt light bulb is left on for 10 hours. How much electrical energy does it consume in kilowatt-hours?
1. A0.1 kilowatt-hour
2. B1 kilowatt-hour
3. C10 kilowatt-hours
4. D100 kilowatt-hours
Show answer
Answer: B. 1 kilowatt-hour
Energy equals power multiplied by time, so 100 watts times 10 hours gives 1,000 watt-hours, and dividing by 1,000 converts that to 1 kilowatt-hour. Answering 10 kilowatt-hours treats the 100-watt bulb as though it drew a full kilowatt. A kilowatt-hour is a unit of energy, while a watt is a unit of power, which is energy per unit time.
Key insight: Power times time equals energy, so watts times hours gives watt-hours before any unit conversion.
Question 5Advanced
A household uses 900 kilowatt-hours of electricity during a 30-day month. If one solar panel produces an average of 1.5 kilowatt-hours per day, how many panels are needed to supply that entire monthly demand?
1. A20 panels
2. B30 panels
3. C45 panels
4. D600 panels
Show answer
Answer: A. 20 panels
One panel produces 1.5 kilowatt-hours per day times 30 days, which is 45 kilowatt-hours per month, and 900 divided by 45 gives 20 panels. The distractor 600 comes from dividing the monthly demand by the daily output of one panel, which mismatches a monthly quantity with a daily one. Writing the units on each factor exposes that mismatch immediately.
Key insight: Convert every quantity to the same time period before dividing, or the answer will be off by that factor.

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Unit 6: Energy Resources and Consumption