Energy Revision Notes

Non-renewable fossil fuels—coal, oil, and natural gas—have historically powered industrial growth and remain the dominant energy sources worldwide. These fuels are formed over millions of years from organic matter and are finite, meaning they will eventually deplete.

Coal is abundant and widely used for electricity generation, especially in developing countries like India and China, due to its availability and low cost. Oil is crucial for transport fuels and petrochemicals, with countries like Saudi Arabia and Russia being major producers. Natural gas is valued for its cleaner combustion compared to coal and oil and is used for heating, electricity, and industry.

The reliance on fossil fuels is linked to economic development because they provide reliable, high-density energy essential for manufacturing, transport, and urbanisation. However, their extraction and use contribute significantly to air pollution and greenhouse gas emissions, driving climate change. This environmental impact is a growing concern globally, prompting shifts towards cleaner energy sources.

• Coal, oil, and natural gas supply the majority of global energy needs.
• They are finite resources formed over millions of years.
• Fossil fuels are central to industrial and economic development.
• Their use causes pollution and greenhouse gas emissions.

Renewable energy sources include geothermal, wind, hydroelectric, wave, tidal power, solar energy, and biofuels. Unlike fossil fuels, these sources are naturally replenished and generally have a lower environmental impact.

Hydroelectric power harnesses flowing water to generate electricity and is significant in countries with suitable rivers and topography, such as Norway and Brazil. Wind power is expanding rapidly in countries like Denmark and the USA, where wind conditions are favourable. Solar energy is versatile and increasingly affordable, with high uptake in sunny regions like Australia and parts of Africa.

Biofuels, derived from organic materials like crops or waste, can replace fossil fuels in transport but may compete with food production. Geothermal energy exploits heat from the Earth's interior, effective in volcanic regions such as Iceland. Wave and tidal power are emerging technologies with potential in coastal areas but are currently limited by cost and technology maturity.

• Renewables are naturally replenished and more sustainable.
• Hydroelectric, wind, and solar are the most widely used renewables.
• Biofuels can substitute fossil fuels but may affect food supply.
• Geothermal, wave, and tidal power have regional potential but limited global use.

Nuclear energy generates electricity through nuclear fission, producing large amounts of energy with minimal greenhouse gas emissions during operation. It provides a stable, high-output power source, supporting countries like France and Japan in reducing fossil fuel dependence.

However, nuclear energy has significant drawbacks. The risk of accidents, as seen in Chernobyl and Fukushima, raises safety concerns. Radioactive waste disposal remains unresolved, requiring secure storage for thousands of years. Nuclear plants are expensive to build and decommission, and public opposition can delay projects.

Despite these challenges, nuclear energy is considered by some as a low-carbon alternative to fossil fuels, especially where renewable resources are insufficient or intermittent.

• Nuclear power produces large, stable electricity with low operational emissions.
• Risks include accidents and long-term radioactive waste.
• High costs and public opposition limit expansion.
• It can complement renewables in low-carbon energy strategies.

Renewable energy sources offer environmental benefits by reducing carbon emissions and pollution. They promote energy security by diversifying supply and reducing dependence on imported fuels.

However, many renewables face challenges such as intermittency—solar and wind depend on weather conditions, requiring storage or backup systems. Initial capital costs can be high, though operational costs are generally low. Some technologies, like hydroelectric dams, can disrupt ecosystems and displace communities.

The suitability of renewable sources varies by country based on geography, climate, and economic capacity. For example, Iceland exploits geothermal energy effectively, while Kenya invests in wind and geothermal to expand access to electricity.

• Renewables reduce emissions and enhance energy security.
• Intermittency requires storage or backup solutions.
• High upfront costs but low operating expenses.
• Environmental and social impacts vary by technology and location.

Germany provides a clear example of a country balancing energy sources amid development and environmental goals. Historically reliant on coal and nuclear power, Germany has committed to the Energiewende policy to transition towards renewables.

Wind and solar power have expanded rapidly, supplying a growing share of electricity. Coal use is being phased out, and nuclear plants are scheduled for closure. This shift aims to reduce greenhouse gas emissions and dependence on imported fossil fuels.

Challenges include managing the intermittency of renewables, requiring grid upgrades and energy storage solutions. Energy prices have risen, affecting consumers and industry. Germany's experience highlights the complexity of transitioning energy systems while maintaining reliability and affordability.

• Germany is transitioning from coal and nuclear to renewables.
• Wind and solar are major growth areas in electricity supply.
• Intermittency and costs present ongoing challenges.
• The case illustrates trade-offs in energy policy and development.