Quad: |
The quad is a unit of energy equal to 1^{15} BTU. It is roughly equivalent to the energy content of 8 billion gallons of gasoline. |

ExaJoule: |
The exaJoule is equal to 10^{18} joules. Energy in the United States used per year is roughly 95 EJ. |

Btu: |
The British Thermal Unit, or BTU , is the amount of energy required to heat one pound of water by 1 degree F. |

kWh: |
The kiloWatt-hour (kWh) is a unit of energy equivalent to one kiloWatt of power expended for one hour of time. An average US household consumes energy at a rate of about 1 kW. |

MWh: |
The megaWatt-hour (MWh) is a unit of energy equivalent to one thousand kiloWatts of power expended for one hour of time. A high-powered electric locomotive requires about 5 MW of power. |

BOE: |
The heat content of crude oil from different countries varies from about 5.6 million Btu (MMBtu) per barrel to about 6.3 MBtu. In the US and Canada, one blue barrel (bbl) is equivalent to 42 US gallons. |

Toe: |
The tonne of oil (toe) is a unit of energy equivalent to the energy content of 1000 kg of crude oil, and often varies depending on the source. |

mcf: |
Mcf is a unit of energy equivalent to the energy content of 1000 cubic feet (ft^{3}) of natural gas, and often varies depending on the source. |