The Science of Energy

Basic Energy Concepts

• Energy vs. Power:

  • Energy is the capacity to do work or produce heat.

  • Power is the rate at which energy is used or produced (energy per unit time).

• Types of Energy:

  • Potential Energy: Stored energy due to position (e.g., chemical, nuclear, gravitational).

  • Kinetic Energy: Energy of motion (e.g., heat, light, mechanical).

• Energy Density: Higher energy density fuels (e.g., gasoline) store more energy per unit volume or mass.

Units of Energy

• Joule (J): Standard SI unit of energy.

• Calorie (c): Heat required to raise 1g of water by 1°C.

• Kilowatt-hour (kWh): Electric energy usage over time (not a power unit).

• British Thermal Unit (BTU): Energy needed to heat 1 lb of water by 1°F.

• Conversions Available Online: No need to memorize conversion factors.

Laws of Thermodynamics

• First Law (Conservation of Energy): Energy cannot be created or destroyed, only transformed.

• Second Law (Entropy): Energy transformations are not 100% efficient; entropy (disorder) always increases.

  • Example: Burning fuel to generate electricity loses energy as heat.

• Implications: No perpetual motion machines are possible.

Energy Return on Investment (EROI)

• EROI Formula: EROI=Energy Delivered to SocietyEnergy Put into that Activity\text{EROI} = \frac{\text{Energy Delivered to Society}}{\text{Energy Put into that Activity}}EROI=Energy Put into that ActivityEnergy Delivered to Society​

• Historical Trends:

  • 1930s: 100 barrels of oil per barrel invested.

  • 1970s: 25:1

  • 1990s: 11-18:1

  • Current (New Oil Discoveries): ~3:1

• Higher EROI = More efficient energy source.

Fossil Fuels & Energy Independence

• Fossil Fuels: Coal, oil, natural gas; formed from ancient organic material.

• Peak Oil (Hubbert’s Peak): Predicted oil production would peak in the 1970s.

• Energy Independence:

  • The U.S. was energy self-sufficient until the 1970s.

  • Fracking (since 2008) increased oil and gas production, delaying peak oil effects.

• 1970s Energy Crisis: Arab embargo + U.S. oil peak led to shortages.

Primary & Secondary Energy Sources

• Primary Energy: Naturally occurring energy sources (solar, coal, oil, natural gas, nuclear).

• Secondary Energy: Converted from primary sources (electricity, hydrogen fuel).

Impact of Energy on Society

• Dependence on Fossil Fuels:

  • Agriculture (fertilizers, irrigation, machinery).

  • Transportation (cars, shipping, aviation).

  • Industry & manufacturing.

• Energy & Economy:

  • Nations with higher energy consumption tend to have higher GDP.

  • Energy shortages can trigger economic crises.

Renewable & Alternative Energy

• Renewable Energy Sources: Solar, wind, hydro, geothermal, biomass.

• Nuclear Energy: Uses fission of uranium/plutonium (potential future in fusion).

• Challenges: Efficiency, storage, infrastructure, and transition costs.