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)