Unit 6: Energy Resources and Consumption

Energy transformations

Conversions of energy from one form to another (e.g., chemical → thermal → mechanical → electrical); humans mostly transform energy rather than “use it up.”

Nuclear fusion

Process in the Sun’s core that joins atomic nuclei and converts nuclear energy into heat and radiant (electromagnetic) energy.

Chemical energy

Energy stored in chemical bonds between atoms in molecules.

Electrical energy

Energy resulting from the motion of electrons.

Electromagnetic energy (radiant energy)

Energy that travels as waves, such as sunlight.

Mechanical energy

Energy made up of potential energy and kinetic energy.

Potential energy

Stored energy due to an object’s position or configuration.

Kinetic energy

Energy of motion.

Nuclear energy

Energy stored in atomic nuclei; released by fission (splitting atoms) or fusion (joining atoms).

Thermal energy

Energy an object has due to the movement of its molecules (heat-related energy).

Energy

The capacity to do work or produce heat.

Power

The rate at which energy is transferred or used (Power = Energy/time).

Kilowatt-hour (kWh)

A unit of energy used on electric bills; calculated as Power (kW) × time (h).

British thermal unit (Btu)

Amount of heat required to raise the temperature of 1 pound of water by 1°F.

Horsepower (HP)

Power unit used in automobiles; 1 HP = 746 watts.

Zeroth Law of Thermodynamics

If A is in thermal equilibrium with B and with C, then B and C are in thermal equilibrium with each other.

First Law of Thermodynamics

Conservation of energy: energy cannot be created or destroyed.

Second Law of Thermodynamics

In any energy conversion, useful work is less than heat supplied; some energy becomes less available (often as waste heat).

High-quality energy

Concentrated energy capable of doing lots of useful work (example: electricity).

Low-quality energy

Dispersed energy (often low-temperature heat) that is difficult to convert into useful work.

Energy efficiency

Fraction of input energy that becomes useful output (Efficiency = useful output/total input).

Conservation (energy)

Reducing energy use by using less of a service or changing behavior (e.g., driving less, turning things off).

Renewable energy

Energy collected from resources naturally replenished on a human time scale.

Nonrenewable energy

Energy sources that form over geologic time and are not sustainable on human time scales (e.g., fossil fuels).

Energy carrier

A form of energy that is produced from primary sources and delivered for use (e.g., electricity, hydrogen), not a primary source itself.

Turbine

Device spun by moving fluid (steam, wind, water) that converts fluid energy into mechanical rotational energy.

Generator

Device that converts mechanical energy (often from a turbine) into electrical energy.

Baseload demand

The minimum, steady level of electricity demand on the grid.

Peak demand

Higher-demand periods (e.g., hot afternoons with heavy air-conditioning use).

Transmission lines

Long-distance, high-voltage power lines that move electricity from generation sites toward users.

Distribution lines

Local power lines that deliver electricity from substations to homes and businesses.

Cogeneration (combined heat and power, CHP)

System that captures waste heat from electricity generation and uses it for heating/industrial processes, increasing overall efficiency.

Fossil fuels

Nonrenewable energy-rich materials (coal, oil, natural gas) formed from ancient organic matter over millions of years.

Peat

Partially decayed vegetation/organic matter formed in acidic, anaerobic conditions; can be an early stage in coal formation.

Methane hydrates (clathrates)

Methane trapped in an ice-like structure at low temperature and high pressure (e.g., permafrost, ocean floor).

Tar sands (oil sands)

Deposits containing bitumen (semi-solid oil) that require mining or steam-based extraction and significant processing.

Combustion

Chemical reaction (often burning hydrocarbons) that produces CO₂, H₂O, and energy; also can create pollutants depending on conditions/impurities.

Life-cycle thinking

Evaluating impacts across a fuel’s full chain: extraction → processing → transport → use/combustion → waste/cleanup.

Law of Supply

All else equal, as price increases, the quantity suppliers offer increases (and vice versa).

Law of Demand

All else equal, as price increases, the quantity purchased decreases (and vice versa).

Lignite

Low-rank (“brown”) coal with lower energy content and often higher impurities; widely used for electricity generation.

Acid mine drainage

Acidic runoff formed when sulfide minerals exposed by mining react with oxygen and water, producing sulfuric acid and mobilizing metals.

Scrubbers (flue-gas desulfurization)

Pollution-control devices that “wash out” acidic gases from exhaust, especially sulfur dioxide (SO₂), and can reduce some particulates.

Carbon capture and storage (CCS)

Technology that captures CO₂ from emissions and stores it underground; reduces climate impacts but adds cost and an energy penalty.

Hydraulic fracturing (fracking)

Well development process that injects water, sand, and chemicals at high pressure to create/expand fractures and increase oil/gas flow.

Methane leakage

Release of methane during natural gas extraction/processing/transport; important because methane is a potent greenhouse gas.

Nuclear fission

Splitting a heavy atomic nucleus to release heat, which is used to make steam that spins a turbine-generator in nuclear power plants.

Critical mass

Minimum amount of U-235 needed to sustain a nuclear chain reaction.

Control rods

Reactor components inserted/withdrawn to absorb neutrons and slow or control the fission chain reaction.

Photovoltaic (PV) cell

Semiconductor device that converts sunlight directly into electricity.

Concentrated solar power (CSP)

Solar technology that uses mirrors to concentrate sunlight to heat a fluid, producing steam to spin a turbine and generate electricity.