Lecture 1 Energy Concepts, Consumption and Use

Energy

Definition of Energy

• Ability to cause and do "work" or to move something or heat something.

• Uses of energy include:

  • Electricity and Transportation

  • Producing light

  • Powering technology

Units of Energy/Power

• Power: Rate of energy transfer over time (W)

  • Units: W (watt)

    • 1 W = 1 J/s (J = joule, s = second)

    • Horsepower (HP) mostly used in auto industry, 1 HP = 746 watts.

• Energy: Ability to do work.

  • Units include:

    • Btu (British Thermal Unit) - commonly used in the U.S.

      • 1 BTU = 1055 J

    • J (joule) - used in most other countries.

    • kWh (kilowatt hour) - commonly seen in electricity billing.

      • 1 kWh = 1 kW of power for 1 hour.

    • cal (calorie) - energy required to raise 1 g of H2O by 1°C.

      • 1 kcal = 1 Cal = 1000 cal.

Types of Fuel and Energy Density

Forms of Energy

• Mechanical: Movement of objects or substances.

• Thermal: Internal energy from constant movement of atoms and molecules.

• Nuclear: Energy stored in an atom's nucleus.

• Chemical: Energy stored in chemical bonds between atoms.

• Electromagnetic: Travels in waves (EM radiation).

• Electrical: Movement of electrons.

Calculations

• Refer to examples on pages 242-245.

• Use of calculators may be allowed on exams.

• Focus on understanding general unit conversions, specific problem types are less important.

Thermodynamics

First Law of Thermodynamics

• Conservation of energy: Total energy of an isolated system is constant; energy transforms between forms but cannot be created or destroyed.

• Example: Chemical energy can be transformed into mechanical energy.

Second Law of Thermodynamics

• Energy conversion results in less useful energy as energy quality decreases (energy released as heat).

• In cyclic processes, entropy will either increase or remain the same.

• Entropy: Measure of disorder in a system and energy inaccessible for useful work.

Conservation of Energy on a Tire Swing

• At highest position: All energy is stored as potential energy.

• At lowest position: All energy is kinetic energy.

• With each swing, friction slows it down, converting energy into heat until it stops.

Energy Transformation Chart

• Potential Energy <-> Kinetic Energy <-> Electric Energy

• Indicates energy storage and loss.

Energy Inefficiency

• Cars lose energy through friction resulting in heat.

• Internal Combustion Engine Vehicles (ICEV) have 16-25% energy converted from power to wheels.

• Battery Electric Vehicles (BEV) have 86-90% energy conversion efficiency.

Energy Generation

• Power plants primarily boil water:

  • Water is boiled to create steam, which spins a turbine connected to a generator.

  • Common in: Nuclear, geothermal, coal, and natural gas plants.

Energy Consumption

• Refers to the data and statistics of how energy is utilized.

Historical and Global Energy Context

Power Outages

• Example: February 2021 Texas power outage resulting in 246 confirmed deaths related to hypothermia.

Climate Change and Energy Management

• Jet stream weakening due to warm temperatures around the North Pole.

• Private companies' inadequate maintenance of electrical infrastructure.

Our Energy Consumption Over Time

• Industrial and post-industrial countries utilize more energy while representing a small percentage of the global population.

• The U.S. is approximately 4% of the world's population but consumes roughly 17% of global energy resources.

Changes in Energy Sources

• Historically, coal dominated energy use during the industrial age.

• Mid-20th century saw a shift towards petroleum (oil) dominance.

• Current leading sources include natural gas and petroleum.

Energy by End-Use Sector

• Breakdown of energy usage per sector.

Energy Consumption by Source and End-Use Sector

• Visual representation of energy consumption per sector and source.

Less Developed Countries (LDC) Energy Use

• Rely on subsistence fuels like wood, charcoal, and biomass.

Energy Crisis and International Politics

• The U.S. has been a net oil importer since the 1940s, often reliant on OPEC for oil supply.

• International politics influence oil prices due to production control dynamics.