Renewable Energy — Drills · Grade 12 Science

Chapter: Energy, Water & Material Resources

What these drills covers

By the end of Renewable Energy you should be able to:

6 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: renewable energy, photovoltaic (PV) cell, intermittency, capacity factor.

Problem 1

Which device turns sunlight straight into electricity?
  1. A photovoltaic (solar) cell
  2. A wind turbine
  3. A hydroelectric dam
  4. A steam boiler
Answer and explanation

A photovoltaic (solar) cell

A photovoltaic cell converts sunlight directly into electricity with no moving parts.

Problem 2

Which renewable source taps the natural heat from inside the Earth?
  1. Solar
  2. Geothermal
  3. Wind
  4. Biomass
Answer and explanation

Geothermal

Geothermal energy uses hot water and steam from Earth's interior to generate power or heat buildings.

Problem 3

A geothermal plant has a nameplate capacity of 50 MW and averages 45 MW of output over the year. What is its capacity factor, as a percent?
Answer and explanation

90 %

Capacity factor = 45 / 50 = 0.90 = 90%. Geothermal runs steadily, so its capacity factor is high.

Problem 4

Solar and wind are called 'intermittent' because they...
  1. never produce any electricity
  2. produce constant power day and night
  3. only produce power when the sun shines or the wind blows
  4. release large amounts of greenhouse gases
Answer and explanation

only produce power when the sun shines or the wind blows

Intermittent sources depend on nature's timing, generating power only when the sun or wind is available.

Problem 5

Which of these is a real trade-off of large hydroelectric dams?
  1. They must burn fuel to run
  2. They emit more CO2 than a coal plant
  3. They only operate in daylight
  4. They flood land and block fish migration
Answer and explanation

They flood land and block fish migration

The electricity is clean, but the dam floods land behind it, blocks migrating fish, and reshapes the river — genuine ecological costs.

Problem 6

Explain why building a lot of solar and wind power makes energy storage, like large batteries, more important.
Answer and explanation

Solar and wind are intermittent: they generate a surplus when it is sunny or windy and little at other times, which often does not line up with when people actually need electricity. Energy storage captures the surplus and releases it later, filling the gaps when the sun sets or the wind drops so the grid stays reliable.

Browse all courses