A small portable instrument used to measure and record the total accumulated personal dose of ionizing radiation.

A dopant, also called a doping agent, is a trace of impurity element that is introduced into a chemical material to alter its original electrical or optical properties.

Domestic energy poverty refers to a situation where a household does not have access or cannot afford to have the basic energy or energy services to achieve day to day living requirements.

Domestic energy consumption is the total amount of energy used in a house for household work.

A system where heat is distributed to residential or commercial properties from a central location.

A distribution transformer or service transformer is a transformer that provides the final voltage transformation in the electric power distribution system, stepping down the voltage used in the distribution lines to the level used by the customer.

A distribution substation transfers power from the transmission system to the distribution system of an area.

A distribution board (also known as panelboard, breaker panel, or electric panel) is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit in a common enclosure.

Wind turbines installed on the "customer" side of the electric meter, or are installed at or near the place where the energy they produce will be used.

A system made up of smaller, individual pumping stations (one flow center for each heat pump) each controlled individually by the operation of the specific heat pump unit that they serve.

Distributed generation, also distributed energy, on-site generation, or district/decentralized energy, is electrical generation and storage performed by a variety of small, grid-connected or distribution system-connected devices referred to as distributed energy resources.

Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation.

A fuel oil that is derived from the distillation operations.

The height above ground level where wind speed is theoretically zero based on the effects of ground cover.

In the physical sciences and electrical engineering, dispersion relations describe the effect of dispersion on the properties of waves in a medium.

In fluid dynamics, dispersion of water waves generally refers to frequency dispersion, which means that waves of different wavelengths travel at different phase speeds.

Electricity sources that can be brought online on demand.

The ability of a power plant to increase and decrease output quickly on demand.

A stand alone parabolic reflector which produces temeperatures in a working fluid up to 700 °C (1,292 °F).

In electrical engineering, a disconnector, disconnect switch or isolator switch is used to ensure that an electrical circuit is completely de-energized for service or maintenance.