4.1.3 National and Global Energy Resources

To power our homes, transport, and industry, we rely on various energy resources. These are categorized based on whether they can be "replenished" or not.

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1. Renewable vs. Non-Renewable Resources

1. Non-renewable energy resources are finite. They will eventually run out and cannot be replaced once used.
2. Renewable energy resources are those that are being (or can be) replenished as they are used. They will never run out.

2. Primary Energy Resources

You must know the specific advantages and disadvantages of each resource for the AQA exam.

Non-Renewables

Renewables

3. Energy Trends and the Environment

Global energy use has historically been dominated by fossil fuels. However, there is a significant shift occurring due to:

1. Environmental Impact: Greenhouse gases like carbon dioxide ($CO_2$) lead to climate change.
2. Sustainability: The realization that fossil fuels are running out.
3. Science & Politics: International agreements (like the Paris Agreement) pressure governments to invest in "green" technology.

4. Reliability and the "Baseload"

A key concept in energy management is reliability.

1. Base load: The constant minimum level of electricity demand. This is usually met by nuclear and coal/gas because they provide a steady, 24/7 output.
2. Variable Demand: Renewables like wind and solar are "intermittent." We cannot rely on them alone unless we develop better energy storage (like giant batteries) or use them alongside gas power stations that can be turned on quickly.

5. Edge Cases and Common Misconceptions

Carbon Neutrality: Biofuels are often called "carbon neutral" because the $CO_2$ they release when burned is the same amount the plant absorbed while growing. However, energy used in farming and transport often makes them slightly "carbon positive."

Nuclear is NOT Fossil Fuel: Many students mistakenly group nuclear with fossil fuels because it is non-renewable. Remember: Nuclear does not produce carbon dioxide or contribute to global warming.

Mathematical Application: Comparing Energy

While this topic is largely descriptive, you may be asked to interpret data or calculate efficiency (from 4.1.2.2) of a power station.

Example: A wind turbine has a maximum power output of 2 MW (2,000,000 W). Over 24 hours, it only produces 24 MWh of energy due to low wind speeds.

Calculate its average power.

$\text{Average Power}=\frac{\text{Total Energy}}{\text{Total Time}}$

$\text{Average Power}=\frac{24\text{ MWh}}{24\text{ hours}}=1\text{ MW}$

This shows the turbine was only operating at 50% capacity.