Glossary Glossary

The following definitions reflect those used by the International Energy Agency (IEA); definitions used by other organisations and publications may vary.

G20

group of 20 finance ministers and central bank governors. The group is made up of all G8 members, plus Argentina, Australia, Brazil, China, India, Indonesia, Mexico, Saudi Arabia, South Africa, South Korea and Turkey. The European Union is the twentieth member.

G2V

grid-to-vehicle

G8

group of eight industrialised nations – Canada, France, Germany, Italy, Japan, Russia, United Kingdom and the United States.

GDP

gross domestic product

GFCF

gross fixed capital formation

GHG

greenhouse gases

GHP

geothermal heat pumps

GIS

Green Investment Scheme

GIS

geographic information systems

GREET

The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation Model

GSHP

ground-source heat pumps

GTL

gas-to-liquids

gas

 includes natural gas (both associated and non-associated with petroleum deposits, but excluding natural gas liquids) and gas-works gas.
 

gas-to-liquids

a process featuring reaction of methane with oxygen or steam to produce syngas (a mixture of hydrogen and carbon monoxide) followed by synthesis of liquid products (such as diesel and naphtha) from the syngas using Fischer-Tropsch catalytic synthesis. The process is similar to those used in coal-to-liquids or biomass-to-liquids.

geothermal

energy available as heat emitted from within the earth’s crust, usually in the form of hot water or steam.

global warming

the observed increased of the global average temperature as a result of human and other activities, including through the increased concentration of greenhouse gases such as CO2 from energy.

green certificates

amount of electricity produced by green methods;set by regulations but can be traded.

greenhouse effect

greenhouse gases (such as water vapour, CO2, methane, etc) in the atmosphere absorb and re-emit heat being radiated from the earth, trapping warmth. 

greenhouse gases

referring to gases that contribute to the greenhouse effect by absorbing infrared radiation (heat). Anthropogenic emissions of six greenhouse gases are covered by the Kyoto Protocol.

gross domestic product (GDP)

a country’s annual economic output.

g

gramme

gal

gallon (US or UK)
 

gce

gramme of coal equivalent

gCO2/km

gramme of carbon dioxide per kilometre

gCO2/kWh

gramme of carbon dioxide per kilowatt-hour

GHa

giga-hectare (1 hectare x 109)

GJ

gigajoule (1 joule x 109)

GJ/t

gigajoule per tonne

Gt

gigatonne (1 tonne x 109)

GtCO2-eq

gigatonne of carbon-dioxide equivalent (using 100-year global warming potentials for different greenhouse gases)

GW

gigawatt (1 Watt x 109)

GWh

gigawatt-hour

GWth

gigawatt thermal (1 Watt x 109)