Butanol may be used as a fuel in an internal combustion engine.

Butane is an alkane with the formula C4H10. it is a gas at room temperature and atmospheric pressure, is a highly flammable, colorless, easily liquefied gas that quickly vaporizes at room temperature. Normal butane can be used for gasoline blending and as a fuel gas.

In electric power, a bushing is a hollow electrical insulator that allows an electrical conductor to pass safely through a conducting barrier such as the case of a transformer or circuit breaker without making electrical contact with it.

A busbar is a metallic strip or bar, typically housed inside switchgear, panel boards, and busway enclosures for local high current power distribution.

In electric power distribution, a bus duct (also called busway) is a sheet metal duct or also cast resin insulated containing either copper or aluminium busbars for the purpose of conducting a substantial current of electricity.

Burnup is a measure of how much energy is extracted from a primary nuclear fuel source. It is measured as the fraction of fuel atoms that underwent fission.

Buoyancy, or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object.

Bunding, also called a bund wall, is a constructed retaining wall around storage "where potentially polluting substances are handled, processed or stored, for the purposes of containing any unintended escape of material from that area until such time as a remedial action can be taken.

Building-integrated photovoltaics are photovoltaic materials that are used to replace conventional building materials in parts of the building envelope such as the roof, skylights, or facades.

A computer-based control system installed in buildings that controls and monitors the building's mechanical and electrical equipment such as ventilation, lighting, power systems, fire systems, and security systems.

A building envelope is the physical separator between the conditioned and unconditioned environment of a building including the resistance to air, water, heat, light, and noise transfer.

In electric power distribution and transmission, a Buchholz relay is a safety device mounted on some oil-filled power transformers and reactors, equipped with an external overhead oil reservoir called a "conservator".

A brush or carbon brush is an electrical contact which conducts current between stationary wires and moving parts, most commonly in a rotating shaft.

A brownout is an intentional or unintentional drop in voltage in an electrical power supply system.

Brownfield land is any previously developed land that is not currently in use that may be potentially contaminated.

Broadband over power lines (BPL) is a method of power line communication (PLC) that allows relatively high-speed digital data transmission over the public electric power distribution wiring.

The British thermal unit (BTU or Btu) is a unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

A briquette is a compressed block of coal dust or other combustible biomass material (e.g. charcoal, sawdust, wood chips, peat, or paper) used for fuel and kindling to start a fire.

Brine is a high-concentration solution of salt (NaCl) in water (H2O).

A breeder reactor is a nuclear reactor that generates more fissile material than it consumes.