Energy: Renewable and Non-Renewable Resources — HS Environmental Science practice questions

A challenge for wind and solar power is that they:

1. release large amounts of CO₂
2. produce radioactive waste
3. depend on the weather
4. use up their fuel source

Answer: C — depend on the weather

C) Correct — They produce power only when wind or sun is available; storage and grid planning help balance supply. A) They emit almost none while operating. B) Describes nuclear. D) Wind and sunlight are renewable.

In a typical coal power plant, most of the fuel's energy:

1. is lost as waste heat
2. becomes electricity
3. is stored for later use
4. is turned back into coal

Answer: A — is lost as waste heat

A) Correct — Only about a third becomes electricity. B) Efficiency is only about 33–40%. C) Plants do not store most energy. D) Energy cannot be turned back into fuel.

Replacing an incandescent bulb with an LED saves energy because the LED:

1. makes heat instead of light
2. wastes less energy as heat
3. runs on renewable energy only
4. uses more electricity but lasts longer

Answer: B — wastes less energy as heat

B) Correct — LEDs turn more electricity into light and use about 75–80% less electricity for the same light. A) Incandescent bulbs waste energy as heat. C) Bulbs use whatever the grid supplies. D) LEDs use less electricity.

Natural gas burns cleaner than coal, but a climate concern is:

1. it releases more CO₂ per unit of energy than coal
2. methane leaks from wells and pipes
3. it produces radioactive waste
4. it depends on the weather

Answer: B — methane leaks from wells and pipes

B) Correct — Methane is a strong greenhouse gas. A) It releases less. C) Nuclear power does. D) Describes wind and solar.

Geothermal energy uses heat from:

1. sunlight stored in surface soil
2. burning wood underground
3. ocean tides
4. Earth's interior

Answer: D — Earth's interior

D) Correct — Wells reach hot water and steam underground. A) Is shallow solar heat. B) Nothing is burned. C) Is tidal energy.

A major drawback of nuclear fission power is:

1. high CO₂ emissions during operation
2. output that depends on the weather
3. long-lived radioactive waste
4. short plant lifetimes

Answer: C — long-lived radioactive waste

C) Correct — It stays dangerous for thousands of years; safe long-term storage is a challenge. A) Nuclear plants emit very little CO₂. B) Describes wind and solar. D) Plants often run 40 years or more.

Solar power pros/cons?

Pros: clean, abundant, declining costs. Cons: intermittent, requires land, panel manufacturing.

Worked example — Radioactive half-life: Plutonium-239 has a half-life of ~24,000 years. If a sample contains 800 g today, how much remains after 72,000 years (assuming no removal)?

Step 1 — Find number of half-lives: 72,000 ÷ 24,000 = 3 half-lives. Step 2 — Apply halving: 800 → 400 (1) → 200 (2) → 100 g (3). Step 3 — Interpret: 100 g remains after 72,000 years. This is why high-level nuclear waste storage must be secure for hundreds of thousands of years — a key challenge for nuclear power.

Fossil fuels?

Coal, oil, natural gas. Limited supply. Burning releases CO2.

Energy efficiency?

Use less energy for same output. Insulation, LEDs, efficient appliances.