AP Environmental Science

## Learning Outcomes

- Explain why **industrialization** increases total energy demand
- Distinguish between **energy demand**, **primary energy consumption**, **electricity use**, and **energy intensity**
- Describe how mechanization, manufacturing, transport, and rising incomes drive energy consumption upward
- Interpret the relationship between economic development and energy use without confusing correlation and causation
- Use simple calculations and data reasoning to compare total energy use, per-capita energy use, and efficiency
- Evaluate environmental effects of rising energy demand and identify ways to reduce impacts without stopping development

## AP Environmental Science Syllabus

For the AP Environmental Science, you are expected to understand how industrialization increases energy demand, with a focus on the following syllabus points:

- Know that as the world becomes more industrialized, overall energy demand increases
- Identify **mechanization**, manufacturing, transportation, and electrification as major drivers of higher energy consumption
- Understand that **industrial sectors** account for the largest share of global energy use
- Explain the difference between **primary energy consumption** and **electricity consumption**
- Distinguish **total energy demand** from **energy intensity**
- Understand that developing and emerging economies account for most recent growth in global energy demand
- Recognise that industrial growth has historically increased **fossil fuel consumption**, especially coal, oil, and natural gas
- Explain one environmental consequence of rising energy demand and one strategy to reduce that impact

## Test Your Knowledge

_Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, look more closely at that area during your revision._

1. Why does industrialization usually increase a country's energy demand?
2. What is the difference between **energy intensity** and **energy use per person**?
3. Why can a country become more energy-efficient but still use more total energy?
4. Name two sectors of an industrializing economy that sharply increase energy use.
5. Why is industrialization often linked to higher fossil fuel use?

## Introduction

Industrialization is one of the clearest reasons global energy demand rises. When an economy shifts from small-scale farming and hand labor toward factories, machines, transport networks, and large cities, it starts using much more commercial energy. This is not just because there are “more machines.” It is because energy becomes built into almost every part of economic life: growing food, making goods, moving materials, powering homes, and providing electricity.

For AP Environmental Science, this topic matters because it links **Unit 6 energy use** to later units on **air pollution**, **climate change**, and **resource management**. If you can explain the chain from industrialization to higher energy demand to environmental effects, you are well prepared for both multiple-choice questions and free-response responses.

> **Key Term: industrialization**
> The shift from a mainly agrarian economy to one based on factory production, large-scale industry, mechanization, and expanded infrastructure.

### How industrialization raises energy demand

Industrialization increases energy demand because it replaces direct human and animal labor with powered systems. In a pre-industrial economy, many tasks are done by people, draft animals, or simple tools. In an industrial economy, the same tasks are done by tractors, pumps, motors, furnaces, assembly lines, and freight systems. Each of those systems requires fuel or electricity.

> **Key Term: mechanization**
> The replacement of human or animal labor with machines powered by fuels or electricity.

Think through the process step by step.

In agriculture, mechanization means tractors replace plows pulled by animals, irrigation pumps replace manual water lifting, and harvesters replace hand cutting. This raises food output, but it also raises energy use because machinery runs on fuel and fertilizers and pesticides often require fossil fuels in production and transport. So even if agriculture becomes more productive, it also becomes more energy-intensive in commercial terms.

In manufacturing, the increase is even larger. Factories run machinery for cutting, molding, heating, cooling, and packaging. Heavy industries such as **steel**, **cement**, and **chemicals** need especially large energy inputs because they involve high-temperature processes. A cement kiln, for example, needs sustained heat. A steel plant also needs major energy input, not just once, but continuously.

Construction also increases energy demand. Industrializing countries build roads, bridges, ports, power lines, apartments, and factories. Making cement, steel, glass, bricks, and asphalt all requires energy. Then more energy is needed to transport those materials and use heavy machinery on site.

Transport demand rises at the same time. A more industrial economy moves more raw materials to factories and more finished products to ports, warehouses, and shops. Trucks, railways, ships, and sometimes aircraft all expand. This is why industrialization often increases oil demand, since transport systems rely heavily on petroleum fuels.

> **Key Term: energy demand**
> The amount of energy needed by households, industry, transport, and other sectors to carry out activities.

A common mistake is to treat factories as the only cause. In reality, industrialization increases demand through several connected systems at once:

- mechanized agriculture
- expanding manufacturing
- construction and infrastructure
- transport of materials and goods
- rising household electricity use

That last factor matters more than students sometimes expect. As incomes rise, people buy appliances, lighting, fans, refrigerators, phones, and air conditioning. This means industrialization raises energy demand both directly in production and indirectly through changing lifestyles.

> **Test Tip:** In an FRQ, do not just state “industrialization increases energy use.” Add at least two mechanisms such as mechanization, factory production, transport, or household electrification to earn fuller credit.

### Primary energy, electricity, and energy intensity

Students often confuse several similar terms. APES questions may test these differences directly or use them in graphs.

> **Key Term: primary energy consumption**
> Total energy demand from raw energy sources before they are converted into electricity or refined fuels.

Primary energy includes coal, crude oil, natural gas, uranium, biomass, solar input captured for use, and other raw energy sources. It is broader than electricity. This matters because a country can use energy for many purposes besides electricity generation, especially transport and industrial heating.

Electricity is only one form of end-use energy. It is a very important one, and it is the fastest-growing form of end-use consumption globally, but it is not the same as total energy use. For example, trucks burning diesel increase total energy demand even if electricity use stays constant.

Now compare total energy demand with energy intensity.

> **Key Term: energy intensity**
> The amount of energy used per unit of GDP; a measure of how much energy an economy needs to produce economic output.

Energy intensity is about efficiency relative to economic production. Total energy demand is the whole amount used. A country can reduce energy intensity while still increasing total energy demand if the economy grows fast enough.

Here is the logic:

- factories become more efficient
- appliances use less electricity
- transport improves fuel economy

These changes lower energy used per dollar of GDP. But if population rises, incomes rise, and production rises even faster, the country may still consume more energy overall.

This distinction is central to exam questions. Industrializing economies often improve efficiency over time, yet their total demand still rises because they are building more, producing more, and consuming more.

### Interpreting global trends and data

Recent global patterns fit this model well. World energy consumption is projected to rise sharply over coming decades, with much of that increase concentrated in developing regions, especially Asia. Industrial sectors already account for the largest share of global energy consumption among end users. That means the part of the economy most tied to industrialization is also the biggest energy user.

The course material also notes that energy use growth is strongest in developing countries. This makes sense. Many developed countries already industrialized long ago, so their growth is slower. By contrast, emerging economies are expanding infrastructure, manufacturing, and electricity access now.

A useful APES relationship is:

> **Total energy use = population × energy use per person**

This is not a difficult formula, but it helps explain why total energy demand can rise quickly.

### Worked example

A country has a population of **50 million** and uses **40 gigajoules of energy per person per year**.

Calculate total annual energy use.

Step 1: write the formula

Total energy use = population × energy use per person

Step 2: substitute values

Total energy use = 50,000,000 people × 40 GJ/person/year

Step 3: calculate

Total energy use = 2,000,000,000 GJ/year

So the country's total annual energy use is **2.0 billion GJ per year**.

Now imagine industrialization raises energy use per person to **55 GJ/person/year**, while population rises to **52 million**.

New total energy use = 52,000,000 × 55  
= 2,860,000,000 GJ/year

Increase in total energy use = 2.86 billion − 2.00 billion  
= **0.86 billion GJ/year**

This shows how industrialization can drive demand upward through both greater per-capita use and population growth.

> **Test Tip:** When interpreting energy graphs, check whether the figure shows total energy use, per-capita use, or energy intensity. Many wrong answers come from mixing up these three measures.

Students should also avoid claiming a perfect causal law between GDP per capita and energy use per person. The relationship is strong, but not absolute. Some countries are more efficient. Others have service-based economies. Climate, geography, infrastructure, and policy all matter.

So the safest exam wording is: **higher GDP per capita is generally associated with higher energy use per person**, not “always causes.”

### Why fossil fuel use often rises during industrialization

Historically, industrialization has depended heavily on fossil fuels. Coal powered early factories and steam engines. Oil later became dominant in transport. Natural gas expanded for electricity, heating, and industrial use.

This pattern persists because fossil fuels have several practical advantages:

- high energy density
- established extraction and transport systems
- existing engines and power plants
- ability to provide continuous energy, not just intermittent supply

Coal still plays a major role in global electricity generation, and oil remains central to transportation. Natural gas is often seen as a lower-emission fossil fuel than coal, but it still contributes carbon dioxide emissions, and methane leakage can worsen warming.

Industrialization does not have to follow exactly the same fossil-fuel path in every country. Some countries can expand renewables faster, improve building efficiency, and electrify transport sooner. But historically, and still in many places today, industrialization has meant greater fossil fuel consumption.

This links directly to later APES topics. More fossil fuel use can lead to:

- more **carbon dioxide** emissions and climate change
- more **nitrogen oxides** and **sulfur dioxide** from combustion
- more **particulates** and smog
- more extraction impacts from mining and drilling

A strong APES answer should make that connection clearly.

### How development can continue with lower environmental impact

The exam may ask you to suggest a solution that reduces environmental harm without blocking economic development. A good answer avoids saying “stop industrialization.” That is unrealistic and does not address real human needs.

Instead, stronger answers focus on changing **how** development happens.

One strategy is improving energy efficiency. If factories use efficient motors, buildings use better insulation, and appliances use less electricity, then energy intensity can fall even while GDP rises.

A second strategy is electrification using lower-carbon electricity sources. If an industrializing country expands solar, wind, hydroelectric, or nuclear electricity instead of relying only on coal, it can reduce air pollution and greenhouse gas emissions.

A third strategy is improving transport systems. Public transit, rail freight, and efficient logistics reduce the energy needed per unit of transport.

A fourth strategy is material efficiency and recycling. If industry reuses metals and other materials, it reduces the need for mining and energy-intensive primary production.

A balanced APES judgement is this: industrialization usually increases total energy demand, but the size of the environmental impact depends on the **fuel mix**, **efficiency**, **technology**, and **policy choices**.

That is the kind of “it depends” reasoning the exam rewards.

## Key Point Checklist

_This article has covered the following key knowledge points:_

- Industrialization is the shift from agrarian production to machine-based industry and infrastructure
- Industrialization increases energy demand because machines, factories, transport, and urban systems all require fuel or electricity
- Mechanization raises commercial energy use in both agriculture and industry
- Industrial sectors account for the largest share of global energy consumption
- Primary energy consumption means total demand from raw energy sources before conversion
- Electricity consumption is only one part of total energy use
- Energy intensity means energy used per unit of GDP
- Total energy demand can rise even when energy intensity falls
- Energy use per person generally rises with GDP per capita, though the relationship is not perfect
- Developing and emerging economies account for most recent growth in global energy demand
- Industrialization has historically increased fossil fuel use, especially coal, oil, and natural gas
- Environmental impacts of rising energy demand can be reduced through efficiency, electrification, cleaner energy, and better transport systems

## Key Terms and Concepts

- industrialization
- mechanization
- energy demand
- primary energy consumption
- energy intensity


Global Energy Consumption - Industrialization increases energy demand