A renewable energy resource is one that is replenished naturally on a short timescale and will not run out.
Renewable resources in the syllabus
| Resource | Energy source | How it generates electricity |
|---|---|---|
| Solar | Sunlight | Photovoltaic cells convert light to electricity directly |
| Wind | Moving air | Wind turns turbine blades connected to a generator |
| Hydroelectric | Falling water | Water released from a dam drives a turbine |
| Geothermal | Heat from inside the Earth | Hot rock heats water to steam, which drives a turbine |
| Tidal | Gravitational pull of the Moon | Moving tidal water drives a turbine |
| Wave | Surface waves on water | Wave motion drives a floating generator |
| Biomass | Organic material (wood, waste, crops) | Burned to heat water to steam, or converted to biogas |
Common advantages
- Will not run out (sustainable).
- Produce no carbon dioxide during operation (except biomass, which is approximately carbon-neutral over its growth cycle).
- Low running costs once built.
Common disadvantages
- Intermittent: solar depends on sunlight, wind depends on wind speed. Output is not constant.
- Low power density: large areas of land or sea may be needed.
- High initial construction cost.
- Visual or environmental impact (e.g. wind turbines on landscapes, dams flooding valleys).
Common errors and how to correct them
Stating that renewable resources produce “no pollution.” Manufacturing solar panels and wind turbines involves energy and materials. The correct statement is that they produce no greenhouse gases during operation.
Calling all renewables “unreliable.” Hydroelectric and geothermal can provide constant output. The correct term for solar and wind is “intermittent” rather than unreliable.
How to apply this in an exam
When asked to evaluate a resource, give at least one advantage and one disadvantage specific to that resource, not generic statements that apply to all renewables.
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