A half-cell is a structure that contains a conductive electrode and a surrounding conductive electrolyte separated by a naturally occurring Helmholtz double layer.

Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species.

A device used for measuring or maintaining orientation and angular velocity, used in positioning for offshore wind turbines.

A guy-wire, guy-line, or guy-rope, also known as simply a guy, is a tensioned cable designed to add stability to a free-standing structure.

Gas to Liquids

A growler is an electrical device used for testing insulation of a motor for shorted coils.

The practice of making a conscious effort to form a hydraulic barrier in a geothermal borehole to protect the integrity of the deep earth environment.

A material used during the grouting process specifically designed to form a hydraulic barrier in a geothermal borehole to promote transfer between the ground sorce heat exchanger piping and the earth.

Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way down into groundwater.

Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations.

A grounding transformer or earthing transformer is a type of auxiliary transformer used in three-phase electric power systems to provide a ground path to either an ungrounded wye or a delta-connected system.

A ground-coupled heat exchanger is an underground heat exchanger that can capture heat from and/or dissipate heat to the ground.

A heat pump system that uses the ground as a heat source and/or heat sink.

Ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the earth.

A ground loop or earth loop occurs when two points of a circuit are intended to have the same ground reference potential but instead have a different potential between them.

A grid-tied electrical system, also called tied to grid or grid tie system, is a semi-autonomous electrical generation or grid energy storage system which links to the mains to feed excess capacity back to the local mains electrical grid.

Grid-tie inverters used in solar systems, match phase with a utility-supplied sine wave. Grid-tie inverters are designed to shut down automatically upon loss of utility supply, for safety reasons.

Grid storage enables the storage of generated elctricity during low demand periods that can be dispatched during peak or high demand periods.

The reliability and consistency in power or electricity production.

Grid parity (or socket parity) occurs when an alternative energy source can generate power at a levelized cost of electricity (LCOE) that is less than or equal to the price of power from the electricity grid.