Explain how renewable energy resources are driven by continuous Earth-system energy flows

What this dot point is asking

SCSA wants you to connect each renewable energy resource to the Earth-system flow that drives it, and to explain why these flows make the resource renewable. The contrast with fossil fuels is deliberate: fossil fuels tap a fixed stock of ancient energy, while renewables tap ongoing energy flows.

Solar-driven resources

The Sun is the master driver of most renewable resources.

• Solar energy captures sunlight directly, using photovoltaic panels or solar thermal systems. WA's high, reliable solar radiation, especially in the Pilbara and Mid West, makes it an excellent solar resource.
• Wind energy exists because the Sun heats Earth's surface unevenly, creating pressure differences that drive air movement. Turbines convert this kinetic energy to electricity. The Albany wind farm uses the strong, consistent winds of the Southern Ocean coast.
• Hydropower relies on the water cycle: solar energy evaporates water that later falls as rain and flows downhill, and the moving or falling water turns turbines.
• Wave energy draws on wind energy transferred to the ocean surface, so it too traces back to solar heating.

Non-solar renewable resources

Two important renewable flows do not come from the Sun.

• Tidal energy comes from the gravitational pull of the Moon and Sun on the oceans, which raises and lowers sea level. The rise and fall, or the resulting currents, can drive turbines.
• Geothermal energy comes from heat within Earth, produced largely by the decay of radioactive elements. It can heat water or generate electricity where hot rock is accessible.

Why these resources are renewable

A resource is renewable when it is replenished as fast as, or faster than, it is used. Renewable energy resources work because they tap continuous flows: the Sun keeps shining, the wind keeps blowing, the tides keep turning and Earth keeps producing internal heat. Using the energy does not deplete the flow. This is the crucial contrast with fossil fuels, which draw down a stock that took millions of years to build. Renewables do still have limits, such as intermittency for solar and wind and suitable sites for hydro and geothermal, so a strong answer recognises both their renewability and their practical constraints.

Intermittency, storage and the grid

A genuine evaluation of renewables must address intermittency, because it is the main reason a grid cannot simply switch entirely to solar and wind overnight. Solar output peaks at midday and vanishes at night; wind rises and falls with weather. To match this variable supply to demand, grids use energy storage (large batteries, or pumped hydro that pumps water uphill when surplus power is available and releases it when needed), geographic spreading of wind and solar farms so a lull in one place is offset elsewhere, and a diverse mix of sources. Western Australia's South West Interconnected System illustrates the challenge: as rooftop solar grows, managing the swing between low midday demand and the evening peak becomes the central engineering problem. Recognising that the renewable flow is inexhaustible but its timing is not controllable is the sophisticated point examiners reward.