National and Global Energy Trends

This lesson explores how energy use is changing at national and global levels, the social, economic, and environmental factors that influence energy choices, and the challenges of meeting growing energy demand sustainably. This is part of the AQA GCSE Physics specification (Section 4.1).

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Global Energy Demand

The world's total energy demand has increased significantly over the past century and continues to rise. This is driven by:

Factor	Explanation
Population growth	More people means greater demand for electricity, heating, and transport
Economic development	As countries develop, they industrialise and consume more energy
Improved living standards	People use more appliances, heating, air conditioning, and vehicles
Technological advances	New technologies (data centres, electric vehicles) create new energy demands

Global Energy Consumption by Source

Energy Source	Approximate Global Share
Oil	~31%
Coal	~27%
Natural gas	~24%
Hydroelectric	~7%
Nuclear	~4%
Wind and solar	~5%
Other renewables	~2%

Note: These figures are approximate and are changing rapidly as renewable capacity grows.

Exam Tip: AQA may give you data on energy use (bar charts, pie charts, tables) and ask you to describe trends. Always quote specific data from the source, describe the trend, and offer an explanation. For example: "Coal use has decreased because of concerns about climate change and the growth of cheaper renewable alternatives."

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UK Energy Trends

The UK's energy mix has changed dramatically in recent decades.

Historical Changes

Period	Dominant Energy Source	Key Development
Pre-1960s	Coal	Coal powered industry and electricity generation
1960s-1990s	Coal and oil, growing gas	North Sea gas discoveries; gas-fired power stations
1990s-2010s	Gas dominant, coal declining	Dash for gas; environmental regulations on coal
2010s-present	Rapid growth in renewables	Wind and solar capacity expanding; coal almost phased out

UK Electricity Generation Mix (Recent Trends)

Source	Trend
Coal	Declining rapidly — now less than 2% of UK electricity
Natural gas	Still significant (~35-40%) but declining
Nuclear	Stable (~15%) but ageing stations are closing
Wind	Rapidly increasing (~25-30%), especially offshore
Solar	Growing (~4-5%)
Biomass	Moderate (~6-8%)
Other renewables	Growing (hydro, tidal pilot projects)

graph LR
    subgraph "UK Energy Mix Change"
        A["1990: Coal 65%, Gas 2%, Nuclear 20%, Renewables 2%"]
        B["2010: Coal 28%, Gas 47%, Nuclear 16%, Renewables 7%"]
        C["2025: Coal <2%, Gas 35%, Nuclear 15%, Renewables 45%"]
    end
    A --> B --> C

Exam Tip: If given a graph or table showing how the UK energy mix has changed over time, you should describe the trends (e.g., "coal has decreased from 65% to less than 2%"), explain the reasons (environmental regulations, cost of renewables falling), and predict future trends (continued growth in wind and solar, decline of gas).

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Factors Influencing Energy Choices

Governments, businesses, and individuals choose energy resources based on several factors.

Environmental Factors

Factor	Impact on Choice
Climate change	Drives the shift away from fossil fuels to reduce CO2 emissions
Air pollution	Burning fossil fuels releases SO2, NOx, and particulates; renewables do not
Habitat destruction	Dams flood valleys; wind farms affect bird populations; mining scars landscapes
Radioactive waste	Nuclear power produces waste that must be safely stored for thousands of years

Economic Factors

Factor	Impact on Choice
Cost of fuel	Fossil fuel prices fluctuate; renewables have no fuel costs
Cost of infrastructure	Building nuclear or hydroelectric plants is very expensive
Job creation	Both fossil fuel and renewable industries create employment
Energy prices for consumers	Governments aim to keep electricity affordable

Social and Political Factors

Factor	Impact on Choice
Energy security	Countries prefer not to rely on imports from politically unstable regions
Public opinion	Opposition to fracking, nuclear, or wind farms can influence policy
International agreements	Paris Agreement commits nations to reducing emissions
Government subsidies	Subsidies for renewables make them more competitive

Exam Tip: When answering questions about why a country's energy mix is changing, think about the three categories: environmental, economic, and social/political. Try to mention at least one factor from each category for a balanced answer.

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The Challenge of Intermittency

One of the biggest challenges with renewable energy is intermittency — many renewable resources do not produce electricity all the time.

Resource	Intermittency Issue
Wind	Wind does not always blow; very calm days produce no electricity
Solar	No generation at night; reduced in cloudy weather and winter
Wave	Wave energy varies with weather and season

Solutions to Intermittency

Solution	How It Helps
Energy storage (batteries)	Store surplus energy for use when generation is low
Pumped storage hydroelectric	Pump water uphill when surplus electricity is available; release it through turbines when demand rises
Backup gas-fired power stations	Can be turned on quickly when renewables are not generating
Grid interconnectors	Import electricity from other countries when domestic supply is low
Demand management	Encourage consumers to use electricity at off-peak times (smart meters, time-of-use tariffs)

graph TD
    A["Renewable generation high (windy/sunny)"] -->|"Surplus energy"| B["Store in batteries / pump water uphill"]
    C["Renewable generation low (calm/dark)"] -->|"Demand exceeds supply"| D["Release stored energy / turn on gas backup"]
    B --> D

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Energy and the Environment: The Bigger Picture

Carbon Footprint

A carbon footprint is the total amount of CO2 and other greenhouse gases emitted over the full life cycle of a product, process, or activity. For energy resources, this includes:

• Emissions during construction of power plants
• Emissions during operation (burning fuel, if applicable)
• Emissions during decommissioning and waste disposal

Resource	Carbon Footprint (g CO2 per kWh)
Coal	~900
Gas	~450
Nuclear	~10-20
Wind	~10-15
Solar	~40-50
Hydroelectric	~5-25