Energy Intensity Definition
Prerequisites
The U.S. economy produces about $27 trillion in GDP and consumes about 93 quads of primary energy per year. In 1980, it produced $7 trillion (inflation-adjusted) on 78 quads. Output nearly quadrupled; energy use grew only 20%. The economy became dramatically less energy-intensive.
Energy intensity is the amount of energy consumed per dollar of GDP, typically expressed as BTU per dollar or megajoules per dollar. Lower energy intensity means the economy wrings more economic output from each unit of energy.
U.S. energy intensity has fallen roughly 2% per year since 1980. This decline has three sources, and confusing them leads to bad policy. First, genuine efficiency gains: better insulation, more efficient motors, LED lighting. These reduce the physical energy needed per unit of output. Second, structural shifts: as the economy moves from manufacturing (energy-intensive) to services (less energy-intensive), overall intensity falls even if no individual process improves. Third, offshoring: importing energy-intensive goods from other countries reduces domestic energy use without reducing global energy use.
Only the first source represents real progress. The second and third can be mistaken for efficiency when they are really about relabeling where energy is consumed.
Worked Example
Country A produces $10 trillion GDP on 50 quads of energy. Country B produces $2 trillion on 20 quads.
- Calculate energy intensity. A: 50/10 = 5 quads per trillion dollars. B: 20/2 = 10 quads per trillion dollars.
Country B is twice as energy-intensive. Does that mean it is less efficient?
Not necessarily. If Country B has a manufacturing-heavy economy and a cold climate, it may need more energy per dollar of output for structural reasons, not because its factories are inefficient. Comparing energy intensity across countries requires decomposing it into efficiency, structure, and trade effects.
Energy intensity is useful for tracking trends within a single economy over time, but misleading as a cross-country comparison without decomposition.
U.S. energy intensity has fallen 50% since 1980. Which of the following would NOT explain part of that decline?
Increasing total energy consumption would, all else equal, raise energy intensity, not lower it. The other three all reduce the ratio of energy to GDP.
The answer is BGo deeper
- Energy Explained · U.S. Energy Information Administration
- National Center for Energy Analytics · Mark Mills et al.
Lesson complete
Next: Decoupling Evidence→