Energy Transitions and Terminology

Medieval Kinetic Energy

windmills, water wheels, sails

Medieval Thermal Energy

wood, charcoal, peat, dung, straw

Outcomes of industrial revolution

• heat to motion

• invention of steam engine — thermal to kinetic

• electricity (1800s) — thermal to kinetic to electrical

U.S. Fuel Mix

• 1800-1850: wood dominant (widespread deforestation)

• 1885-1950: coal dominant (peak whale oil)

• 1950-2026: petroleum dominant

• 2026-present: predicted to be gas dominant

Reason for transition b/w wood and coal

due to rising firewood prices (18-30% of GDP) and falling coal prices

Trend of biofuel consumption

going up

Trend of wood consumption

going down

Trend of wind consumption

going up

Trend of solar/pv consumption

going up

Trend of hydroelectric consumption

going down

Trend of waste consumption

going down

Trend of geothermal consumption

flatlining

Energy transitions

trend toward decarbonization

Wood vs. Coal, which is dirtier?

wood is dirtier than coal at point of combustion (cleaner long term)

Ranking of energy sources by carbon intensity

wood > coal > petroleum > natural gas > renewables

How did projected energy consumption differ from actual consumption

• consumed 30-35 quads less than predicted (of energy)

• didn’t take into account efficiency

• projections for U.S. natural gas imports have dropped (since 2020 exports>imports)

Trend of domestic energy production

going up (oil, gas, wind, solar, geothermal, bioenergy)

Trend of energy consumption and imports

going down

U.S. Emissions peak

peaked at 6 billion metric tons in 2007 and have gone down since

Peak Coal in U.S.

2006

Peak Coal in China

2025

Trend of coal in Spain

coal use went from 36% (2000) to 2% (2023)

Lighting transition

cost has droped > 99.9% since 1700

Transportation transition

• global sales of combustion engine peaked in 2017

• U.S.: peak gasoline in 2018

• China: peak gasoline in 2023

• changes due to electrification

Swift technology substitutions

CRT to LCD

Slow technology substitutions

four techs are responsible for >60% of U.S. energy conversion

Steam Turbine

1884

Gas Turbine

1791

Spark Ignition Engine

1876

Compression-Ignition

1893

Wind Generator

1888

Photovoltaic Cell

1883

Hydrogen Fuel Cell

1839

Wind to make fuels

in 1700’s, the Dutch used wind-powered sramper mills to produce oil from oilseeds (used for illumination)

Important lessons of fuel and tech transitions

• more typical than we expect

• move towards cleaner options

• move towards higher-performing options

• move towards cheaper options

• aren’t many new ideas

• fuel transitions take a long time

• tech transitions can be quick

Biggest energy story

efficiency gains have led us to consume about the same energy as 25 years ago

Primary Energy

original/unconverted fuel sources (crude oil)

Secondary Energy

converted/stored energy (gasoline)

Energy

ability to do work

Units of Energy

• Fuels: BTU (British Thermal Unit), quad (1 quadrillion BTU), Joules, Calories

• Mass: tons

• Density: barrels

Power

rate of energy (work or energy over time)

Units of power

• watt, horsepower

• Consumption at a house: 1-4 kW

• Human consumption: 100 W

Unit conversions

• 1 GWh = 1 mill. kWh

• 1 J = 2.78 × 10^-7 kWh

• 1 kWh = 3,412 BTU

• 1 BTU = 2.93 × 10^-4 kWh

• 1000 SCF = 1 mill. BTU

• 1 ton = 1 tonne

• 1 EJ = 1 Quad

Unit Notation

• watt (w): unit of power

• Joule (J): unit of energy

• Volt (V): electric potential

• MW: megawatts

• MMBTU: million BTU

• MMBBLS: mill. blue barrels

• MMBD: mill. barrels per day