National & Global Energy Resources (AQA GCSE Physics Combined Science): Revision Notes
Energy resources
What are energy resources?
Energy resources are the sources we use to power our transport, heat our homes, and generate electricity. Understanding the difference between renewable and non-renewable resources is crucial for making informed decisions about our energy future.
There are two main types:
Renewable energy resources can be replaced as we use them. They won't run out.
Non-renewable energy resources cannot be replaced once used up. They will eventually run out completely.
The choice between renewable and non-renewable energy sources affects not only our energy security but also environmental sustainability. Most countries are now investing heavily in renewable technologies to reduce dependence on fossil fuels.
Renewable energy resources
Biomass
Biomass comes from living things or things that were recently alive. This includes wood, plant waste, and even methane gas from animal waste.
How it works: Biomass is burned to heat water, creating steam that turns turbines to generate electricity. It can also be used directly as fuel for transport or heating.
Key point: Biomass is carbon neutral. This means the carbon dioxide released when it burns is the same amount the plant took in while it was growing.
Limitations: We need large amounts of land to grow biomass crops, which can compete with food production.
Wind power
Wind turbines use moving air to generate electricity through a simple but effective process.
How it works: Wind turns the blades of turbines, which spin generators to produce electrical energy.
Advantages:
- Clean and free once turbines are built
- No fuel costs or emissions during operation
Limitations: Only works when it's windy. Modern turbines need wind speeds between approximately 3-25 metres per second. They automatically shut down in very high winds for safety reasons.
Hydroelectricity
This uses flowing water to generate electricity and is one of the most established renewable technologies.
How it works: Water stored behind dams flows downhill through turbines, spinning generators to create electricity.
Advantages:
- Very reliable and can be controlled easily
- Can respond quickly to changes in electricity demand
- Reservoirs can provide water storage for communities
Limitations: Won't work during droughts when reservoirs run dry. Large dams can significantly damage local environments and displace communities.
Geothermal energy
This uses heat from inside the Earth, tapping into the planet's natural thermal energy.
How it works: Hot rocks underground heat water, creating steam. This steam can heat homes directly or turn turbines to generate electricity.
Advantages:
- Very reliable because the Earth's heat is constant
- Works 24/7 regardless of weather conditions
- Small land footprint compared to other renewables
Limitations: Only works in certain locations where hot rocks are close to the surface, such as areas with volcanic activity.
Tidal power
This uses the movement of sea water caused by tides, which are driven by gravitational forces from the Moon and Sun.
How it works: Tidal streams or water flowing through barriers turn turbines to generate electricity.
Advantages:
- Tides are very predictable, so we know exactly when energy will be produced
- More predictable than wind or solar power
Limitations: Only works in coastal areas with significant tidal ranges. Can affect marine wildlife habitats and migration patterns. Limited to specific geographical locations where it's economically viable.
Solar power
This uses energy from the Sun, converting sunlight into usable electricity or heat.
How it works: Solar panels (photovoltaic cells) convert sunlight directly into electricity. Solar thermal systems use sunlight to heat water for domestic use or electricity generation.
Advantages:
- Great for remote areas where connecting to the electrical grid is expensive
- Works particularly well in sunny countries
- Becoming increasingly cost-effective
Limitations: Doesn't work at night or during cloudy weather, requiring energy storage systems or backup power sources.
Water waves
This uses the up-and-down movement of sea waves to capture kinetic energy from ocean motion.
How it works: Wave motion turns generators to produce electricity through various mechanical systems that convert wave movement into rotational energy.
Limitations: Very unreliable because wave size changes constantly depending on weather conditions. Technology is still developing and can be damaged by storms. Doesn't work well on calm days.
Non-renewable energy resources
Fossil fuels
These include coal, oil, and natural gas formed from dead organisms that lived millions of years ago under specific geological conditions.
How they work: Fossil fuels are burned in power stations to heat water, creating steam that turns turbines to generate electricity. They're also used directly for transport (petrol, diesel) and heating homes.
Advantages:
- Very reliable and can produce large amounts of energy quickly
- Easy to transport and store
- Existing infrastructure already in place
Major Problems:
- Produce carbon dioxide (CO₂), contributing to global warming and climate change
- Will eventually run out - they're finite resources
- Cause air pollution including sulphur dioxide and particulates
- Oil spills can cause severe environmental damage
Nuclear power
This uses uranium or plutonium fuel in controlled nuclear reactions to generate massive amounts of energy.
How it works: Nuclear fission (splitting atoms) releases huge amounts of energy. This heats water to create steam that turns turbines, similar to fossil fuel power stations.
Advantages:
- Extremely reliable and can operate continuously
- Produces about 10,000 times more energy per kilogramme than fossil fuels
- Doesn't produce carbon dioxide during operation
- Very high energy density
Serious Problems:
- Creates dangerous radioactive waste that stays harmful for thousands of years
- Risk of serious accidents that can affect large areas
- High construction and decommissioning costs
- Nuclear weapons proliferation concerns
Energy Comparison Example:
To power a city of 1 million people for one year:
- Coal: Requires approximately 3 million tonnes
- Natural gas: Requires about 2 billion cubic metres
- Nuclear: Requires only about 30 tonnes of uranium fuel
This demonstrates the incredible energy density of nuclear fuel compared to fossil fuels.
Key Points to Remember:
- Renewable resources can be replaced and won't run out (wind, solar, biomass, hydroelectric, geothermal, tidal, wave)
- Non-renewable resources will eventually run out (fossil fuels, nuclear)
- All energy resources are used for transport, heating, and electricity generation
- Biomass is carbon neutral - it releases the same CO₂ the plant absorbed while growing
- Reliability varies - some renewables only work in certain conditions (sunny, windy, etc.)
- Nuclear power produces the most energy per kilogramme but creates dangerous long-lasting waste
- The world is transitioning towards renewable energy to address climate change and energy security