Renewable and Non-Renewable Energy

This lesson takes a deeper look at renewable energy resources — how they work, their advantages and disadvantages, and how they compare to non-renewable resources. This is part of the AQA GCSE Physics specification (Section 4.1) and is frequently examined.

---

Renewable Energy Resources

Renewable energy resources are naturally replenished and will not run out on a human timescale. They generally produce little or no carbon dioxide during operation, making them better for the environment.

---

Wind Energy

Wind turbines convert the kinetic energy of the wind into electrical energy. The wind turns large blades, which spin a generator inside the turbine.

Feature	Detail
Energy source	Kinetic energy of moving air
How it works	Wind spins blades, which turn a generator
Location	Hilltops, coastal areas, offshore

Advantages and Disadvantages of Wind Energy

Advantages	Disadvantages
No CO2 or pollutants during operation	Intermittent — no electricity when wind does not blow
No fuel costs	Visual impact — some people consider turbines unsightly
Renewable — wind will not run out	Noise — turbines produce a low humming sound
Low running costs	Wildlife — birds and bats can be killed by blades
Can be placed offshore	Each turbine produces relatively small amounts of electricity

Exam Tip: "Intermittent" means the resource is not always available. Wind, solar, and wave are all intermittent. This is a key disadvantage because it means you cannot rely on them alone to meet demand at all times. You need backup generation or energy storage.

---

Solar Energy

Solar energy can be harnessed in two main ways:

Type	How It Works
Solar photovoltaic (PV) cells	Convert light energy directly into electrical energy
Solar thermal panels	Use sunlight to heat water directly

Advantages and Disadvantages of Solar Energy

Advantages	Disadvantages
No CO2 during operation	Intermittent — no electricity at night; less in cloudy weather or winter
No fuel costs	Large area needed for significant output
Renewable	High initial cost of panels
Can be placed on rooftops (no extra land needed)	Manufacturing solar panels has some environmental impact
Low maintenance	Cannot generate at night

---

Hydroelectric Energy

Hydroelectric power (HEP) uses the gravitational potential energy of water stored behind a dam. When the water is released, it flows downhill and turns turbines connected to generators.

graph TD
    A["Water stored in reservoir (GPE)"] -->|"Dam gates opened"| B["Water flows downhill (KE)"]
    B -->|"Turns"| C["Turbine"]
    C -->|"Drives"| D["Generator"]
    D -->|"Produces"| E["Electricity"]

Advantages and Disadvantages of Hydroelectric Energy

Advantages	Disadvantages
No CO2 during operation	Large areas of land flooded to create reservoirs — destroys habitats
Reliable — water can be released on demand	High initial cost of building the dam
Fast response — can start generating very quickly	Limited locations — requires suitable geography
Long lifespan	Social impact — communities may be displaced
Can store energy (pumped storage)	Environmental impact on river ecosystems

Exam Tip: Hydroelectric power is one of the few renewable resources that is also reliable (not intermittent). It can be turned on and off quickly, making it ideal for meeting sudden increases in demand (e.g., during TV advert breaks when millions of people boil kettles).

---

Tidal Energy

Tidal power uses the rise and fall of tides (caused by the gravitational pull of the Moon) to generate electricity. A tidal barrage (dam) across an estuary traps water at high tide and releases it through turbines as the tide goes out.

Advantages	Disadvantages
Predictable — tides are reliable and can be calculated in advance	Very high cost of building a barrage
No CO2 during operation	Habitat disruption — affects estuarine ecosystems
Renewable	Limited locations — only suitable in certain estuaries
Long lifespan	Only generates for part of each tidal cycle

---

Wave Energy

Wave power uses the kinetic energy of ocean waves to generate electricity. Wave-powered generators are placed on or near the surface of the sea.

Advantages	Disadvantages
No CO2 during operation	Intermittent — depends on wave conditions
Renewable	Difficult to maintain in harsh marine environments
No fuel costs	Low power output compared to other resources
	Visual impact in coastal areas
	Still largely in development

---

Geothermal Energy

Geothermal energy comes from the heat within the Earth, originating from radioactive decay in the core and mantle. In some locations, hot rocks are close to the surface and can be used to heat water and generate steam.

Advantages	Disadvantages
No CO2 during operation	Very limited locations — only practical near volcanic/tectonic activity
Reliable — available 24/7	High drilling costs
Renewable	Not widely available in the UK
Low running costs	Potential release of gases trapped underground

---

Bioenergy (Biomass and Biofuels)

Biomass refers to organic materials (wood, crop waste, animal waste) that can be burned to release energy. Biofuels (e.g., biodiesel, bioethanol) are liquid fuels made from plant materials.

Advantages	Disadvantages
Carbon neutral in theory (CO2 absorbed during growth = CO2 released when burned)	Land use — growing crops for biofuel competes with food production
Renewable (plants can be regrown)	Still produces CO2 and particulates when burned
Can provide on-demand power	Large areas of land needed
Uses waste materials	Deforestation risk if poorly managed

Exam Tip: Biofuels are considered carbon neutral because the CO2 released during combustion was previously absorbed by the plants during photosynthesis. However, in practice, energy is used to plant, harvest, and process the biofuel, so it is not truly zero-carbon. AQA may ask you to evaluate this claim critically.

---

Comparing Renewable and Non-Renewable Resources