A small, manually-secured hatch fitted to the hatch cover, used during loading of grain cargoes.

The first practical generator made by Z.

Graphite is a crystalline form of the element carbon with its atoms arranged in a hexagonal structure.

A graphite-moderated reactor is a nuclear reactor that uses carbon as a neutron moderator, which allows natural uranium to be used as nuclear fuel.

Light perforated platform or walkway built up of metal bars, used for access to machinery.

Small stones, used for making a surface for paths, roads, etc.

The gravitation water vortex power plant is a type of micro hydro vortex turbine system which is capable of converting energy in a moving fluid to rotational energy using a low hydraulic head of 0.7–3 metres (2 ft 4 in–9 ft 10 in).

Gravitational energy or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity.

Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies—are brought toward (or gravitate toward) one another.

A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation to oppose the horizontal pressure of water pushing against it. Gravity dams are designed so that each section of the dam is stable and independent of any other dam section.

A piping system in which flow is accomplished solely by the difference between the height of the inlet end and the outlet end.

A device consisting of a tripod, one leg of which acts as a rail for a sliding electrode holder. Once positioned and with the arc struck, the device welds automatically until the holder operates a trip at the bottom of the rail.

A support structure held in place by gravity as used in offshore wind turbine installations.

The gray is a derived unit of ionizing radiation dose in the International System of Units.

A thick oily substance used to reduce friction between two surfaces.

A separator designed to extract vegetable and animal oils from galley grey wastewater before the water is discharged overboard.

Greasestock was an American event held yearly in Yorktown Heights, New York.

Ports in the lakes of Canada and the USA popular for grain, iron ore and coal shipments. In Canada: Port Arthur and Fort William in Lake Superior; Hamilton, Kingston, Toronto and Prescott in Lake Ontario.

Cargo ship developed to carry raw materials and manufactured goods on the Great Lakes. Most of them carry bulk cargoes of grain, iron ore or coal.

Green building (also known as green construction or sustainable building) refers to both a structure and the application of processes that are environmentally responsible and resource-efficient throughout a building's life-cycle: from planning to design, construction, operation, maintenance, renovation, and demolition.