Energy is the ability to do work. The International System of Units (SI) unit of energy across all energy types is the Joule (J). It is defined as the amount of work done by a force of one newton exerted over a distance of one metre.
Power is the rate at which work is delivered. The SI unit of power is the watt (W). One watt is equal to one joule per second (1 W = 1 J/sec). Watt is the common unit for electrical power (sometimes expressed as We) although may be used for thermal power (Wt).
Consumption of electric energy is measured in kilowatt-hours (kWh), which is equal to the power in kilowatts (kW) times the time period (hours (h)).
The average annual energy production or consumption can be expressed in kilowatt-hours per year (kWh/year). For example, a power plant with a capacity of one MW produces 1000 kWh when the plant runs consistently for one hour. If the power plant runs consistently with no downtime for a year (8760 hours), the generator produces 8 760 000 kWh (8 760 MWh) in a year.
Both Joules and Watts are more commonly recorded in multiples.
|EJ||Exajoule - 1018 joules|
|GJ||Gigajoule - 109 joules|
|Gt||Gigatonne - 109 tonnes|
|GW||Gigawatt - 109 watts|
|kt||Kilotonne - thousand (103) tonnes|
|kW||Kilowatt - thousand (103) watts|
|kWh||Kilowatt-hours - thousand (103) watt-hours|
|ML||Megalitre - million (106) litres|
|mmbbl||Million (106) barrels|
|Mt||Million (106) tonnes|
|MW||Megawatts - 106 watts|
|MWh||Megawatt-hours - 106 watt-hours|
|PJ||Petajoules - 1015 joules|
|tcf||Trillion (1012) cubic feet|
|TJ||Terajoules - 1012 joules|
|TWh||Terawatt-hours - 1012 watt-hours|
Multiples of energy measurements in Australia are expressed in standard international decimal classification terms:
Energy production and consumption are typically reported in the SI unit as petajoules (PJ) as used here but in some cases are reported in barrels of oil equivalent (BOE) and million tonnes of oil equivalent (MTOE).
Individual energy resources are commonly reported according to prevailing industry conventions. Petroleum is reported by volume and weight according to either the SI or the United States system as used by the American Petroleum Institute.
In this report energy is reported in SI units (PJ) with the conventional volume or weight equivalent terms widely in use in industry in parentheses.
|Oil and condensate||Production, reserves: Litres (usually millions or billions)or barrels (usually thousands or millions)|
Refinery throughput/capacity: Litres (usually thousands or millions) or barrels per day (usually thousands or millions)
|L, ML, GL|
bbl, kbbl, mmbbl
ML, GL per day
bd, kbd, mmbd
|Natural gas||Cubic feet (usually billions or trillions)Or cubic metres (usually millions or billions of cubic metres)||bcf, tcf|
m3, mcm, bcm
|LNG||Tonnes (usually millions)|
Production rate: Million tonnes per year
|LPG||Litres (usually megalitres) or barrels (usually millions)||L, ML|
|Coal||Tonnes (usually millions or billions)|
Production rate: tonnes per year (usually kilotonnesor million tonnes per year)
|t, Mt, Gt|
|Uranium||Tonnes (usually kilotonnes) of uranium or of uranium oxide||t U; kt U|
t U3O8; kt U3O8
|Electricity||Capacity: watts, kilowatts, etc|
Production or use: watt-hours, kilowatt-hours, etc
|W, kW, MW|
Wh, kWh, MWh
|Bioenergy||Tonnes (or thousands of tonnes)||t, kt|
|Oil and condensate||1 barrel||=||158.987 litres|
|1 gigalitre (GL)||=||6.2898 million barrels|
|1 tonne (t)||=||1250 litres (indigenous)/|
1160 litres (imported)
|Ethanol||1 tonne||=||1266 litres|
|Methanol||1 tonne||=||1263 litres|
|1 tonne||=||1760 - 1960 litres|
|1 tonne||=||1866 litres|
|Natural gas||1 cubic metre (m3)||=||35.315 cubic feet (cf)|
|Liquefied natural gas||1 tonne||=||2174 litres|
|Electricity||1 kilowatt-hour (kWh)||=||3.6 megajoules (MJ)|
The energy content of individual resources may vary, depending on the source, the quality of the resource, impurities content, extent of pre-processing, technologies used, and so on. The following table provides a range of measured energy contents and, where appropriate, the accepted average conversion factor.
|Crude oil and condensate|
|New South Wales|
|23.9 - 30.0|
|Lignite (Brown Coal)|
* The usable energy content of uranium metal (U) is 0.56 petajoules per tonne, and that of uranium oxide (U3O8) is 0.47 petajoules per tonne. The oxide contains 84.8 per cent of the metal by weight
Source: BREE; Geoscience Australia