Unit 6: Energy Resources and Consumption
AP Environmental Science: 50 practice questions with detailed explanations.
Unit Study Guide
Executive Summary
Unit 6 covers where energy comes from and what it costs: fossil fuels, nuclear, and renewables, plus the efficiency and conservation that multiply their value.
Nonrenewables
Fossil fuels supply most global energy: coal (abundant, dirtiest, mostly electricity), oil (transport fuel), natural gas (cleaner-burning, methane leakage is a concern). They are finite and emit CO₂. Nuclear fission (uranium) is carbon-free but leaves radioactive waste and carries accident risk.
Renewables
Solar (photovoltaic and thermal), wind, hydroelectric, geothermal, biomass, and ocean energy. Wind and solar are intermittent — storage and grid upgrades matter. Hydroelectric is dispatchable but dams block fish and flood land. Biomass is renewable but can compete with food crops.
Efficiency and conservation
Energy efficiency gets more work per unit input (LEDs, heat pumps); conservation uses less (behavior). Cogeneration captures waste heat. The second law of thermodynamics caps efficiency: some energy always degrades to heat. Energy return on investment (EROEI) measures net energy.
Exam traps
Nuclear power is not a fossil fuel and emits no CO₂ in operation — but it is nonrenewable. Renewables have environmental costs too (turbine bird strikes, panel materials). Energy is conserved (first law) but its usefulness degrades (second law).