The kilogram is the base unit of mass in the International System of Units (SI).

A kill switch, also known as an emergency stop, emergency off and as an emergency power off, is a safety mechanism used to shut off machinery in an emergency, when it cannot be shut down in the usual manner.

The kelvin is the base unit of temperature in the International System of Units (SI), having the unit symbol K.

Jumble winding or scramble winding is a type of winding of a wire randomly wound on a bobbin.

Joule heating is the process by which the passage of an electric current through a conductor produces heat.

The joule is a derived unit of energy in the International System of Units. It is equal to the energy transferred to an object when a force of one newton acts on that object in the direction of the force's motion through a distance of one metre.

Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines.

A jackup rig or a self-elevating unit is a type of mobile platform that consists of a buoyant hull fitted with a number of movable legs, capable of raising its hull over the surface of the sea.

The largest solar electric generating system in the world generating 392 megawats by concentraing sunlight through 173,500 heliostats. Located in the Mohave desert in the USA.

Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes.

Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number.

An isothermal process is a type of thermodynamic process in which the temperature of the system remains constant.

A switch used to break an electrical circuit thereby completely de-energising the circuit.

An isolated thermodynamic system has walls that are non-conductive of heat and perfectly reflective of all radiation, that are rigid and immovable, and that are impermeable to all forms of matter and all forces.

The output of two or more generators which is controlled via the prime mover speed governors to maintain the desired frequency during load imbalances.

An isobaric process is a type of thermodynamic process in which the pressure of the system stays constant.

Isobars are atoms (nuclides) of different chemical elements that have the same number of nucleons.

Islay LIMPET was the world's first commercial wave power device and was connected to the United Kingdom's National Grid. (Now decommisioned).

Islanding is the condition in which a distributed generator (DG) continues to power a location even though external electrical grid power is no longer present.

An island grid is constructed when an area is too far from or it is not cost efficient to connect it to a major power grid.