The Science of Energy

Energy

The capacity to do work or produce heat.

Power

The rate at which energy is used or produced (energy per unit time).

Potential Energy

Stored energy due to position, such as chemical, nuclear, or gravitational energy.

Kinetic Energy

Energy of motion, which includes heat, light, and mechanical energy.

Energy Density

The amount of energy stored per unit volume or mass in fuels (e.g., gasoline).

Joule

The standard SI unit of energy.

Calorie

The heat required to raise the temperature of 1g of water by 1°C.

Kilowatt-hour

A measure of electric energy usage over time; not a power unit.

British Thermal Unit (BTU)

The amount of energy needed to heat 1 lb of water by 1°F.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed.

Second Law of Thermodynamics

Energy transformations are not 100% efficient; entropy (disorder) always increases.

Energy Return on Investment (EROI)

A formula that measures the efficiency of energy sources: EROI = Energy Delivered to Society / Energy Put into that Activity.

Peak Oil

The point at which oil production reaches its maximum rate, after which production rates decline.

Primary Energy Sources

Naturally occurring energy sources such as solar, coal, oil, natural gas, and nuclear.

Secondary Energy Sources

Energy that is converted from primary energy sources, including electricity and hydrogen fuel.

Renewable Energy Sources

Energy sources that are replenished naturally, such as solar, wind, hydro, geothermal, and biomass.

Nuclear Energy

Energy produced from the fission of uranium/plutonium, with potential future development in fusion.

Fracking

A method of extracting oil and gas from the ground, increasing production since 2008.

1970s Energy Crisis

A crisis caused by the Arab oil embargo and U.S. oil peak that led to energy shortages.