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Global Energy
Consumption

Explore how the world produces, distributes, and uses energy: from fossil fuels to renewables, and the environmental consequences that follow.

AP Environmental Science

What Is Energy Consumption?

Energy consumption refers to the total amount of energy used by a population, nation, or the entire world over a given period. It is typically measured in units like quads (quadrillion BTU), exajoules (EJ), or terawatt-hours (TWh).

Primary vs Secondary Energy

Primary Energy
Energy found in nature that has not been converted: crude oil, coal, natural gas, sunlight, wind, uranium ore.
Secondary Energy
Energy converted from primary sources into usable forms: electricity, gasoline, hydrogen fuel cells.

The Global Energy Mix

0% 10% 20% 30% 40% 31% Oil 26% Coal 24% Gas 7% Hydro 4% Nuclear 8% Renew.

Energy Units & Conversions

Unit Symbol Equivalent
Joule J \( 1 \) J (base SI unit)
Kilowatt-hour kWh \( 3.6 \times 10^6 \) J
British Thermal Unit BTU \( 1{,}055 \) J
Quad quad \( 10^{15} \) BTU \( \approx 1.055 \) EJ
Exajoule EJ \( 10^{18} \) J

Per Capita Energy Consumption

Total energy use alone does not reveal how equitably energy is distributed. Per capita consumption divides total energy by population:

United States
\( \approx 300 \) GJ per person per year: among the highest globally.
India
\( \approx 25 \) GJ per person per year: roughly \( \frac{1}{12} \) of the US rate.

Nonrenewable vs Renewable Sources

Feature Nonrenewable Renewable
Replenishment Millions of years Days to decades
Examples Coal, oil, natural gas, uranium Solar, wind, hydro, geothermal
\( \text{CO}_2 \) Emissions High (combustion) Low to zero (operation)
EROI Range \( 10{:}1 \) to \( 80{:}1 \) \( 5{:}1 \) to \( 25{:}1 \)
Reliability Dispatchable (on-demand) Intermittent (variable)

Energy Return on Investment (EROI)

Hydro
\( \sim 100{:}1 \)
 Coal
\( \sim 30{:}1 \)
 Wind
\( \sim 20{:}1 \)
 Nat. Gas
\( \sim 15{:}1 \)
 Solar PV
\( \sim 10{:}1 \)
 Ethanol
\( \sim 3{:}1 \)

Energy Flow: Source to End Use

Fossil Fuels Renewables Nuclear Conversion (Power Plants, Refineries) Waste Heat ~60% Industry ~32% Transport ~28% Residential ~22% Commercial ~18%

How to Analyze Energy Data

1
Identify the unit. Is it total energy (EJ) or per capita (GJ/person)? Is it primary or secondary?
2
Check the source mix. What percentage comes from fossil fuels vs renewables? Use proportional reasoning.
3
Convert if necessary. Use the relationship \( 1 \text{ kWh} = 3.6 \times 10^6 \text{ J} \) and \( 1 \text{ quad} \approx 1.055 \text{ EJ} \).
4
Calculate EROI or efficiency. Apply \( \text{EROI} = \frac{E_{\text{out}}}{E_{\text{in}}} \) or \( \text{Efficiency} = \frac{E_{\text{useful}}}{E_{\text{total}}} \times 100\% \).
5
Interpret trends. Is consumption rising or falling? What drives the change: population, GDP, or technology?

Example 1: Unit Conversion

A household uses \( 900 \) kWh of electricity per month. Convert this to joules.

Example 2: Per Capita Comparison

Country A uses \( 50 \) EJ total with a population of \( 200 \) million. Country B uses \( 20 \) EJ total with a population of \( 40 \) million. Which has higher per capita consumption?

Example 3: Efficiency Calculation

A coal power plant burns coal containing \( 1{,}000 \) GJ of chemical energy and produces \( 330 \) GJ of electricity. What is its efficiency?

Trends in Global Energy Growth

200 300 400 500 600 Energy (EJ) 1970 1985 2000 2015 2023 Total

Environmental Impacts of Energy Use

Climate Change
Burning fossil fuels releases \( \text{CO}_2 \) and \( \text{CH}_4 \), intensifying the greenhouse effect.
Air Pollution
Combustion produces \( \text{SO}_2 \), \( \text{NO}_x \), and particulates causing smog and acid rain.
Water Pollution
Oil spills, coal ash, and thermal discharge degrade aquatic ecosystems.
Habitat Loss
Mining, drilling, and dam construction destroy or fragment habitats.

Common Mistakes

✕ Confusing Total & Per Capita
China uses more total energy than the US, but the US has higher per capita consumption. Always check which metric is being asked.
✕ Ignoring Conversion Losses
Students forget that only \( \sim 33\%\text{-}40\% \) of primary energy becomes useful electricity. Don't equate coal burned with electricity delivered.
✕ Conflating Power & Energy
Power (watts) is a rate; energy (joules) is a quantity. A 100 MW plant running for 10 hours produces \( 1{,}000 \) MWh of energy.

Question 1 of 5

Approximately what percentage of global primary energy comes from fossil fuels (oil, coal, and natural gas combined)?

Question 2 of 5

A household uses \( 1{,}200 \) kWh of electricity in one month. How many joules is this?

Question 3 of 5

A natural gas plant has an EROI of \( 15{:}1 \). If \( 2 \) EJ of energy is invested in extraction and processing, how much energy is gained?

Question 4 of 5

Country X consumes \( 40 \) EJ of energy with a population of \( 80 \) million. Country Y consumes \( 100 \) EJ with a population of \( 1 \) billion. Which statement is correct?

Question 5 of 5

A coal-fired power plant has an efficiency of \( 35\% \). If it produces \( 700 \) GJ of electricity, how much total chemical energy from coal was consumed?